tag:blogger.com,1999:blog-45857765248020284352024-03-05T16:49:50.606-08:00Secret Underwater Base / Machine ShopJBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.comBlogger52125tag:blogger.com,1999:blog-4585776524802028435.post-56740793189279547392017-06-02T13:14:00.002-07:002017-06-04T17:17:37.134-07:00New Project (Finished too) - LED Music VisualizerI had built underglow for my computer that was reactive to music about 8 years ago. The system had a number of blue LEDs and would vary the brightness based on the overall volume of the music. I had a low-pass filter integrated into the circuit to make it react preferentially to bass. Unfortunately it has been gracefully failing over the last year to the point where it slowly grows brighter until the LEDs are full brightness all the time. I figured it was time to upgrade to something new and improved and started brainstorming ideas on how to build a new system.<br />
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I know significantly more about circuit design, microprocessor programming, and signal processing than I did 8 years ago (thanks engineering degree) and wanted to go digital instead of analog. I noticed over the last few years the WS2812b individually addressable RGB LED has become the go-to for cool LED projects. The LEDs typically come soldered to flexible strips which can be cut to length. RGB data is passed from LED to LED, so the number of LEDs driven by one microprocessor can be huge.<br />
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My initial plan was to just remake my original underglow setup with a few strips of the WS2812b LEDs, however I figured that wouldn't take advantage of the LEDs being individually addressable. In the middle of thinking about what to build I found a plugin for my computer's keyboard (it has individually addressable LEDs in the keys) that made the keyboard a music visualizer. It displays the frequency components of the music. With the new inspiration I started to look at "going big or going home" for the new music visualizer.<br />
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I started with some blue tape and a tape measure and started figuring out how big my wall mounted visualizer would need to be. As usual the size kept creeping up until I settled on an aspect ratio of 4:1 (left and right speakers each get their own visualizer channel with a 2:1 aspect ratio). To make the visualizer match with my computer setup it needed to be as wide as my monitors (all 3 of them) and the speakers. I ended up with a display area that is 2m wide and 0.5m tall. Strips with various LED densities can be found cheaply on ebay. I decided on the 30 LEDs per meter density. The strips are sold in 5m rolls. I discovered that the rolls were actually made from soldered together 0.5m long segments (no cutting or splicing required if the strips are only 0.5m long). The visualizer would be 15 LEDs tall, and 60 LEDs wide. This also works out to an even number of 6 rolls.<br />
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My blue tape outline for the visualizer above my desk. this is where I first realized how big this project was going to become. <br />
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I also tried to render a basic visualizer design to see how the grid spacing would look.<br />
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Now with the general concept for the visualizer I had to start working out the details. This is also where the numbers got a bit scary for me. Each LED is small and doesn't put out an enormous amount of light. At full brightness on each channel (full bright white light) one of the WS2812b LEDs draws about 60mA at 5V. Easy right? Well... I have a grid of 900 LEDs... A little math now tells me my peak current is more than 50A. That's a lot of current. It's also at 5V, so now I need to worry about voltage drops which could cause LEDs to be dimmer than expected. This means I need to more or less run each strip in parallel with a massive 5V power supply (another quality ebay find).<br />
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The 900 LEDs also puts a strain on the processor. The signal requires accurate timing of the high frequency pulses used to transmit the RGB brightness for each LED. I originally looked at using an Arduino since there are nice libraries for driving the WS2812b LEDs already written, but I concluded the Arduino just didn't have enough juice to drive that many LEDs and deal with running an FFT on two channels of audio. Then I came across the Teensy. This uses a significantly more juiced up processor than a typical Arduino. In addition, it has tons of hardware that can lift the difficulty of driving the LEDs from the actual processor. There was a prebuilt library (and breakout board) for the teensy to drive 8 strips of WS2812b LEDs in parallel using the processors DMA (direct memory access) and hardware PWM modules. I also found prebuilt libraries for sampling the audio and running FFTs on the data. These libraries also took advantage of the hardware built into the Teensy's chip to reduce the load and allow more things to be done in parallel on the processor.<br />
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One more challenge to add to the project... I had to make everything with hand tools (drill, jigsaw, file, etc...). I don't currently have any machine shop access, so I had to go manual on this. I ended up settling on a wooden frame instead of my typical metal construction. Wood ended up being cheaper than metal, easier to source than metal, and easier to work with than metal.</div>
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Here's the frame after making all the 45 degree cuts on a chop saw (I managed to find one I could use) I'm not used to making measurements with a tape measure that end up being the final part size. <br />
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I laid out the frame on my plywood sheet to check sizing <br />
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I was lazy and cut the plywood with a jigsaw in my living room... <br />
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The full frame layout including the board for mounting the LED strips<br />
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I went with a black stain on the wood. I've never finished wood before, so I ended up doing a pretty poor job. Oh well... live and learn!<br />
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This is after separating half of the strips into their 15 LED (0.5m) segments. Dealing with so many parts is really tedious.<br />
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Adhering the strips to the board was extremely time consuming. I tried to make as perfectly square of a grid as possible.<br />
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This is right after I finished adhering all the strips down. After a few hours I noticed a number of the strips were starting to peel off the board...<br />
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I tried to use gaffers tape to hold the LEDs down to the board. I figured if it is designed to stick to carpet, it should stick to wood.<br />
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I was wrong... Gaffers tape did not stay adhered to the wood. Instead it pulled the strips into a tangled adhesive mess. It took me hours to separate each strip from the adhesive roll. This was after attempting to wire some of the strips, so I had to be extra careful to not tear a solder pad off of the strip. I later determined the stain had significantly roughened the surface of the wood. A little bit of sanding and the panel was super smooth, allowing the adhesive to actually stick.<br />
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All of the LEDs remounted and stuck to the freshly sanded board really well. I also added some gaffers tape to the outer segments to make sure a single poorly adhered strip wouldn't cause the array to fail. I also finished the wiring for the strips. Every other strip is fed 5V in parallel from the power supply. Adjacent strips are paired and put in series for power. This is equivalent to driving 30 LED (1m) strips off a single 5V supply. I only used PTFE (Teflon) insulated wire. It doesn't melt during soldering and can handle higher amperage compared to wire with other insulation types. It was also much more annoying to strip compared to the usual types of wire I use.<br />
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First time powering any of the LEDs (only one of 8 groups)! The visualizer is wired in groups of 8 strips (6 strips at the very ends). The Teensy drives 8 strips in parallel, so I could make the frame rate significantly faster by dividing the number of LEDs evenly between the channels.<br />
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After testing each group of strips individually I mated the LED array with the visualizer frame and wired in the signal wires. <br />
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First test with the full grid running! Even without full brightness the array is totally blinding.<br />
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This is the sketchy ebay power supply I'm using to power the LEDs. It is rated for 70A. I question this rating given the quality of the soldering and component placement (it looks like a kindergartner assembled it). I'll be sure to lock out the visualizer from running all LEDs white at full brightness in the code. This should give a reasonable factor of safety on top of whatever the power supply was "designed" to do. There was no manual for the supply and the labels etched on the side of the supply had some poor translations. I was very careful to not electrocute myself. I checked isolation of the casing, and DC outputs from the 120V line. Eventually this will be totally enclosed and untouchable.<br />
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The final array assembly tilted against the wall (before mounting the power supply and processor).<br />
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One of my first tests running the FFT visualizer. I only had one color working at the time. I also hadn't mounted any of the electronics to the frame, so it just sat on the floor<br />
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Testing out the full rainbow effect on the visualizer. I set it on top of my speakers and tipped it against the wall. I'll mount it to the wall later (and make it centered on the desk).<br />
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I still have a few minor details left to complete the visualizer. I still need to add a diffuser to the board, so the led strips and wires are completely hidden. I also need to cover the power supply and other electronics so there is no way to touch the live lines from the wall power. Eventually I'm going to add some bonus features like games on the board (4 player Tetris, snake, pong, helicopter, Pacman, etc..). Since it's so easy to reprogram the processor I can also add new and more interesting visualizers as well. <br />
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This might be my favorite project so far. It wasn't the most work or the
most complicated. It isn't the highest power output or the most
dangerous. However, it is the most aesthetically pleasing. Sometimes I
just want to see music and this is a great way to relax and enjoy
another aspect of my favorite songs. I might also have to pick up DJing in my free time to share the fun!JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com3tag:blogger.com,1999:blog-4585776524802028435.post-28930541519001988452016-08-21T13:40:00.000-07:002017-06-04T17:18:33.058-07:00Mini Combat Robot FinishedI finally found the time and resources to finish the last few parts on the robot. The first and biggest thing was finishing the spinner. I discovered though testing the polyurethane belts I had originally chosen couldn't handle the rotation rate and would stop transmitting any torque (they also melted from slipping). I opted to redesign the spinner using inside-out timing belt. I chose this for a few reasons... I used the timing belt belt inside-out to make sure it could still slip in an impact situation. This prevents the motor from being damaged by the near instant changes in rotation rate. I chose to use timing belt because it's much easier to find small timing belt sizes than it is to find small flat belts. The timing belt also has low stretch cord (fiberglass or kevlar usually) embedded in the belt.<br />
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The new timing belt design required the whole spinner be redesigned and made. Thankfully I had a friend with access to a 5 axis CNC. The new spinner is made from a billet of 7075 aluminum (probably not the best choice because it's more brittle than other alloys) with S7 tool steel teeth. I made sure the design could safely handle 30krpm without ejecting the teeth.<br />
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I disassembled the whole robot again, and broke it down into just the spinner assembly for testing. I had to do a bit of rework on the main plates to fit the shaft properly. The new spinner mounted properly the first try. I also put some armor surrounding the motor shaft to make sure debris can't damage the motor.<br />
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The belt tensioner can be seen on the underside. The original design didn't need one because I was using stretchy polyurethane belt. In this new design, the timing belt is pulled tight by a few ball bearings pressed onto a dowel pin. The dowel pin mount slides back and is locked in place by two screws. The mounting block has a precisely machined slot to keep the bearings perfectly perpendicular to the mount.<br />
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Here is a quick test of the spinner mounted to some random material I had laying around. A friend and I threw objects at the spinner to see how much it could damage it could do. The soda can is one of the most satisfying tests.<br />
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I also tried throwing 2x4s at the spinner. I wasn't taking video at the time, but the hit that damaged this chunk of wood threw the 2x4 well above my head. I quit testing at that point before I did something dumb(er) and injure myself.<br />
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The robot was pretty much done at this point. I just needed to wire everything up and get the top/bottom plates made from metal (I had some temporary laser cut acrylic plates). Unfortunately I couldn't figure out how to get all of the motor controllers and wires to fit. Everything was just too packed in.<br />
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I opted to get new motor controllers for the drive. Hobby brushless motor controllers have come a really long way since I bought the ones for the drive. The old ones were rated for 25 amps each. They also couldn't instantly switch from forward to reverse (dumb "feature" for RC cars). The new controllers (the tiny circuit boards in the picture above) are meant for FPV racing multirotors. They're rated for 30 amps and can instantly switch from forward to reverse (an important feature for multirotors that can fly upside down). I've used these controllers on my hexrotor, so I knew they were good and the ratings were not made up.<br />
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A quick test of the drive ended up shattering the old 3d printed spline couplers. I reprinted the parts with tough resin (a less brittle type of printer resin from Formlabs). These parts held up fine and are still in use.<br />
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I easily fit all of the electronics in the robot. I also finally mounted the power wires in the robot such that the lid could close and seal the battery in.<br />
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A quick test fit showed even the battery could fit. I added some pieces of dense/rigid foam in to keep the battery and spinner ESC in place. The foam has some squish, so it prevents the parts from getting too much force during an impact. I also finally got the top and bottom plates made. I gave up trying to get machine access to make the plates myself. I ended up sending them out to a local shop. They even used the material I had already purchased. The parts ended up really cheap. I will definitely send out any future waterjet parts to this shop. It ends up better quality and even cheaper than me paying for my own machine time at a place like the techshop.<br />
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The plates fit nicely and none of the electronics or wires are badly squished. It was nice seeing it finally done after starting the project more than 3 years ago.<br />
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It makes a really nice display piece of my bookshelf... I don't have any competitions to go to, so finishing this was mostly just to have closure on the project.<br />
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The robot is pretty quick. The new drive ESC make it significantly easier to drive. It rumbles the floor pretty badly, so I probably won't drive this indoors again (don't want to anger the neighbors below).<br />
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A few months after actually finishing the robot I finally got a chance to test it on something. A friend had me pickup some Legos from craigslist for him. He didn't pick them up after the entire summer. Normally I'd be down to play with Legos, but these were kinda gross. They were covered in dirt and who knows what else. They took up room in my living room... something had to be done...<br />
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<iframe allowfullscreen="" class="YOUTUBE-iframe-video" data-thumbnail-src="https://i.ytimg.com/vi/O-eLRVGEr_0/0.jpg" frameborder="0" height="266" src="https://www.youtube.com/embed/O-eLRVGEr_0?feature=player_embedded" width="320"></iframe></div>
My roommate and I made a video to provide some "motivation" for my friend to pickup his Legos. We made a small house using some of the bricks (only the really common or already damaged bricks). The robot instantaneously disassembled the house (ignore my poor driving).<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnlfIbdbgWMnK0AjjjL0aD4F61IWLj-3759zJ-BRVemju18pzd4eA52epPDN5Kb5v-0tC5mGXo6dGugLJsYyn1MEqfGL1XmZgvwWJvr2vZcoUDhv_YQhG6gPDH2O5yiqUpz-n6GFKGXgY/s1600/IMG_20160820_161220.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1197" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnlfIbdbgWMnK0AjjjL0aD4F61IWLj-3759zJ-BRVemju18pzd4eA52epPDN5Kb5v-0tC5mGXo6dGugLJsYyn1MEqfGL1XmZgvwWJvr2vZcoUDhv_YQhG6gPDH2O5yiqUpz-n6GFKGXgY/s320/IMG_20160820_161220.jpg" width="239" /></a></div>
The spinner took a nice chunk out of one of the bricks. The video also worked well. All of the Legos were picked up within a day of posting on Facebook.<br />
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It was nice to finally put this project behind me (actually behind me on a bookshelf). I'll probably never have it actually compete at this point. I probably can't even use it to smash stuff since I don't have an arena or some other safe place to protect me from flying pieces. That being said, it makes a nice desk ornament and could be used if I ever have the immediate need for a small combat robot!<br />
<br />JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-44466568613381274002016-07-25T23:30:00.000-07:002017-06-04T17:19:16.130-07:00Hexrotor FPV Racer<div class="separator" style="clear: both; text-align: center;">
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It took a few months, but I got to the point of being machine limited when FPV racing. When I say machine limited, I mean I basically don't make mistakes and basically run at 100% throttle until the battery dies. The quadrotor also got to the point where it just couldn't keep up with the other racers. When I first started most quads ran with a 3S battery (3 lipo cells, or 11.1V nominal). In the past few months that trend changed to most people flying 4S batteries (14.7V nominal). The extra voltage makes the motors spin faster and provide more thrust. Most of the 4S quads have thrust to weight ratios of about 6:1, with some approaching 10:1. My 3S quadrotor... probably 3:1.<br />
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I first looked at retrofitting my quad to run 4S batteries, but I needed new motor controllers. The bigger battery would also shift the center of mass, making it unbalanced. Given the cost and crappy performance I figured I might as well dump some more money in and build my dream machine.<br />
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The first thing I wanted to do was correct my complaints with the typical frame designs. Mainly I wanted the battery protected from crashes. During the races a number of people would smash their batteries in a crash. LiPos are pretty volatile and I wanted to mitigate the risk of a battery fire. In addition to the battery armor I wanted the arms to be replaceable. It is much cheaper and faster to replace a single arm instead of the entire base frame plate. My quad has a cracked arm, and I didn't want to spend the money on a new frame plate (I fly more gently). Finally, I wanted the frame to be unique.<br />
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This led me to designing my hexrotor. There's one or two hexrotor frames available for purchase (small compared to the hundreds of different quadrotor frames). I also made it radially symmetrical, which is not something I could purchase. The hexrotor factor took care of the unique and cool requirement.<span id="goog_238693417"></span><span id="goog_238693418"></span><br />
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The rest of the hexrotor design focuses around protecting the battery. Most frames have the battery held (exposed) on the top or bottom of the quad with a few velcro straps. I worked to design the hex frame so it wraps around the battery. I split the hex into two portions, a base plate that handles power distribution (battery connector, motor controllers, and all of the wires associated), and a top deck that holds all of the electronics (flight controller, video camera, video transmitter, RC signal receiver, on screen display, and signal LEDs). The battery sits between the electronics deck and the frame. This ensures the battery is safe from damage... or at the very least I'll have already broken all of my electronics before the battery gets damaged. The battery placement also provides a very even weight distribution. The overall center of mass ends up perfectly in the propeller plane, meaning the hex is very well balanced.<br />
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I wanted the hex to be similar in size to a standard quadrotor, so I had to pull the props in closer to each other. This led to a problem... the FPV camera would see the props. Thankfully the top deck design eliminated this problem. The deck sits high enough that a highly tilted camera (necessary for these faster 4S racing quads) wont see the props.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOkwsF8NDqbdu03CILwL2QumXxZ6AsCV1L4zF8K7m-nD32t7EZxUndjHTG8nDOkxo79C0sK5PDfGZTalts67G3FLTfjGV-LhhjbezwbM8chZXJ8lZBEEhpHnuk-jbajbSTwVuYjCUnM1k/s1600/IMG_20160306_212154118_HDR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOkwsF8NDqbdu03CILwL2QumXxZ6AsCV1L4zF8K7m-nD32t7EZxUndjHTG8nDOkxo79C0sK5PDfGZTalts67G3FLTfjGV-LhhjbezwbM8chZXJ8lZBEEhpHnuk-jbajbSTwVuYjCUnM1k/s320/IMG_20160306_212154118_HDR.jpg" width="320" /></a></div>
Here is a printout of my hex in a 1:1 drawing next to my quadrotor. I like to make these 1:1 drawings to get a better feel for the design and to see problems I might miss on the computer. I guess I'm kind of old school for this kind of thing.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjy5DGC-rLNFpRCdvMD72ok_3m464tqDvU3ApuvdvmOVUmSf-DJ_Q8uTfpm-q3KtsYiJ7C7F_yeTdWSveMi-i7FUhyJqfSUg67MYpz1gtJvCpNSAndgXy5sEGlfg04SWJ2YC5kI7jjCttE/s1600/IMG_20160321_190805580.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjy5DGC-rLNFpRCdvMD72ok_3m464tqDvU3ApuvdvmOVUmSf-DJ_Q8uTfpm-q3KtsYiJ7C7F_yeTdWSveMi-i7FUhyJqfSUg67MYpz1gtJvCpNSAndgXy5sEGlfg04SWJ2YC5kI7jjCttE/s320/IMG_20160321_190805580.jpg" width="320" /></a></div>
Without shop access I sent my parts out to be machined. I found a site that did custom carbon fiber parts specifically for FPV racers. The price was better than what I could find for just the raw carbon fiber plate. I ordered enough parts to make two frames as well as spare arms for each frame. The two frames and spares came out to the same cost as the one frame for my quadrotor...<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhb0txE0geIhcpmP31jfjuHeTXxKc11SpkQuA4im4aIyaI4Li1vFQRYR0u90055osv0WxbmNw17fv9uGgFY3V5U8yYbduKhyphenhyphenC1ThGT015zScAcTmTHKY5ho6VwchT1Jtsn3H6h6AhvNgoc/s1600/IMG_20160321_193017955_HDR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhb0txE0geIhcpmP31jfjuHeTXxKc11SpkQuA4im4aIyaI4Li1vFQRYR0u90055osv0WxbmNw17fv9uGgFY3V5U8yYbduKhyphenhyphenC1ThGT015zScAcTmTHKY5ho6VwchT1Jtsn3H6h6AhvNgoc/s320/IMG_20160321_193017955_HDR.jpg" width="320" /></a></div>
The frame is a sandwich of arms between two main base plates. Most existing frames with replaceable arms use 4 screws, some of which are close to the edge of the arm. These arms always break at the screw holes. I used two screws for each arm, directly in the center. This minimizes the loss in strength of the arm from the screw hole placement. I also made sure that the arm will always fail before the base plate. What's the point in having replaceable arms if the base plate cracks instead?<br />
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The max center to center distance on the hex is 270mm, which is only slightly larger than my quadrotor frame which is 250mm.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzIiFjQSxOdWk-bUqKXI_8I-yQYKr5AJ3xCD61Cq5SFITIXpeNI7QUtm-l_i2PB0ICnAseOlWCI00gK-mL1JvdJNq7ODoaoFr4SzuNORyMyeI2eNGYYyvU1XoOxZeL1YVzH-1qeQskcLU/s1600/IMG_20160326_211056487.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzIiFjQSxOdWk-bUqKXI_8I-yQYKr5AJ3xCD61Cq5SFITIXpeNI7QUtm-l_i2PB0ICnAseOlWCI00gK-mL1JvdJNq7ODoaoFr4SzuNORyMyeI2eNGYYyvU1XoOxZeL1YVzH-1qeQskcLU/s320/IMG_20160326_211056487.jpg" width="320" /></a></div>
I 3d printed all of the electronics mounts. This time I used tough resin. The tough resin is a newer formulation from Formlabs (the brand of my 3d printer). It can take significantly more impact before shattering. It also tends to be softer and more flexible.<br />
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I temporarily put the electronics deck on top of the frame to see how it would look. The frame looks very compact until the deck is raised to make room for the battery.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgn3HwoQuL4TUHKQPvArFEKeqc_vNcuV6UJmameBmC3XONObMSqqyLJRIaeICPvhlEfGVSAlsSwgfY2YGcS_My3pEM5BzaC0AV56jZOTazVy2MsvCJuhv5Z6JhjQYG7lJCwgyoSaedNYks/s1600/IMG_20160327_181110480.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgn3HwoQuL4TUHKQPvArFEKeqc_vNcuV6UJmameBmC3XONObMSqqyLJRIaeICPvhlEfGVSAlsSwgfY2YGcS_My3pEM5BzaC0AV56jZOTazVy2MsvCJuhv5Z6JhjQYG7lJCwgyoSaedNYks/s320/IMG_20160327_181110480.jpg" width="320" /></a></div>
I couldn't find a power distribution board (they were all built specifically for quadrotors), so I had to just make a wire bundle. It isn't the most elegant solution, but I made it pretty clean.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkQIfdXBxx_yRIomyoyM45kLYOe8K9kpDldicmVGMG0yFDS05W-H287uBLNi0L2OZw1NFAjF0qFgYUs5Idjjus1uk4EdeA_Y2uDDAW6VO7SxDYDGeJLkE5-h3zOfn2KojKGOZcqvIroLQ/s1600/IMG_20160327_204643815.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkQIfdXBxx_yRIomyoyM45kLYOe8K9kpDldicmVGMG0yFDS05W-H287uBLNi0L2OZw1NFAjF0qFgYUs5Idjjus1uk4EdeA_Y2uDDAW6VO7SxDYDGeJLkE5-h3zOfn2KojKGOZcqvIroLQ/s320/IMG_20160327_204643815.jpg" width="320" /></a></div>
Dealing with all of the wires and motor controllers was a huge pain. Mounting it to the frame took a lot of care to avoid getting things tangled, or putting something in the wrong place.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVYgzuTG3KtlaWGV7BWAWizYQXqdEYE5ab6AZbDeLBhMQlk5h9GCb2scK8WgDb5NSCYNxVaP7CLw2UaFVXLXUUxP1xmAssHH8Ayc2bG30Q4sC3gdBg4A66zzhLXsFbX-u_N3wksl8BV7o/s1600/IMG_20160327_204851231_HDR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVYgzuTG3KtlaWGV7BWAWizYQXqdEYE5ab6AZbDeLBhMQlk5h9GCb2scK8WgDb5NSCYNxVaP7CLw2UaFVXLXUUxP1xmAssHH8Ayc2bG30Q4sC3gdBg4A66zzhLXsFbX-u_N3wksl8BV7o/s320/IMG_20160327_204851231_HDR.jpg" width="320" /></a></div>
My desk was a disaster during the build. I should probably get a dedicated table to work on instead of my computer desk. The good thing is it makes me motivated to finish the project faster, otherwise I basically can't use my computer.<br />
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Here is the completed hex next to my quadrotor. It isn't significantly bigger, but it definitely has the cool and unique factor going on.<br />
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The battery used is a 1800 mAh 4S (14.8V nominal) 75C LiPo. 75C means the battery can be discharged in 1/75 of an hour. Maximum continuous current is 135 amps! (1800 mA*75).<br />
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I added some addressable LEDs to the back. Each one can be set to any color. I have it set up to act as a turn signal as well as change color depending on the throttle and state of the hex (if the flight controller is armed or not).<br />
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The hex stacks up pretty nicely against other quads. The extra thrust is more or less canceled by the extra weight. The hex has no advantage over the quads except for some redundancy (in theory I can lose a prop and still fly). The hex is more dense than the other quads, which makes it slightly less vulnerable to wind. It sounds amazing and has a pretty intimidating effect on the other racers.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT-N8qYwDVgt0wKAR5nSTfG-o2OviSaOtkDYk-tGT5_hXIBLWjDOtbWcjHTrwXVC3PYL3BC6Hg79IFXsizQz0TjQcCkoHU91WuRlzUGD8J1n2eN9H4y3lyZf4EBvE0706_ZBlUozb8IEc/s1600/IMG_20160430_203210032.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT-N8qYwDVgt0wKAR5nSTfG-o2OviSaOtkDYk-tGT5_hXIBLWjDOtbWcjHTrwXVC3PYL3BC6Hg79IFXsizQz0TjQcCkoHU91WuRlzUGD8J1n2eN9H4y3lyZf4EBvE0706_ZBlUozb8IEc/s320/IMG_20160430_203210032.jpg" width="320" /></a></div>
I ended up buying 8 batteries. This easily keeps me flying continuously as long as i have my 4 port battery charger in the field with me.<br />
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The LEDs really saved me in this crashed landing. The grass grew pretty high in the field I race in, and the hex buried itself in. Without the LEDs I might have permanently lost it.<br />
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I also later purchased a gopro and mounted it (5-28-2017). The new mount also came with a bunch of repairs and maintenance. I mostly just had to clean the electronics and replace an antenna that had broken in a nasty crash. It has two antennas (simultaneously receiving), so it didn't cause any issues.<br />
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Overall the hex has been a fantastic build for me. It met all three of my design goals. The arms are replaceable, but I have yet to break or even damage one. I think the sandwich design has enough flex to reduce the stress during an impact. It tends to cartwheel in crashes, which also reduces the forces on the frame. The battery armor design has worked FANTASTICALLY! I have flown into so much stuff, and the battery has been fine every time. As for my uniqueness goal... It really hits the nail on the head. The look and sound really get heads turning. The robustness and mass have also made it a bit terrifying in races. I have had a few mid-air head to head collisions, leaving the other quad needing repairs.<br />
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I will probably build an upgraded frame in the future as new electronics come out (maybe I'll make my own from scratch), or as the racing trends shift. For now, I am happy with the hex and It will be quite a while before I am once again machine limited and require a faster - higher performing machine.<br />
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<br />JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-56065173880464429192015-09-19T16:29:00.000-07:002017-06-04T17:19:47.301-07:00Quadrotor FPV RacerI needed a new hobby. I just don't have the resources to do the kinds of machining projects I have been doing in the past. I kept seeing a really cool concept pop up on various sites: FPV racing. Basically people are building mini quadrotors (5" diameter propellers) and flying through various found obstacles (forests, abandoned buildings, playgrounds, etc...) or purpose built race courses with gates to fly through. Each racing quad had a small analog video camera and video transmitter. This sends low latency video back to the pilot. The pilot wears video goggles so it feels like sitting in the racing quad.<br />
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After watching some videos I knew I had to build one and get into this hobby. There are tons of tutorials online suggesting which parts to get to build one. I figured since I had 0 experience with FPV racing I would go with standard parts and make my own custom one after learning more.<br />
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A week after deciding I was getting into the hobby I had this show up at my door! I pretty much went with the standard parts from Lumenier. This wasn't the cheapest option, but I knew the parts were decent and would work together.<br />
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The frame was much higher quality than I had expected. The edge surface finish and dimensions were all perfect. I hadn't worked with much carbon fiber before this, so I finally got a chance to feel just how good carbon fiber's stiffness to weight ratio was. <br />
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Here's all of the power wiring. There's a nice power distribution board I could use to connect the ESCs. There are also LED boards that let me keep track of the quadrotor when flying without the FPV goggles.<br />
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I made mounts for all of the electronics using 3d printed parts. This was much cleaner looking than the usual hot-glue and tape techniques used in all of the tutorials I saw for building this type of quadrotor.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFiLOCoHgmjcuw2gLQFdk43ku65_WiQbRnFQddVyj2JiSSWtBOhoU4oDDoLwQm5bKWNCbMSYiUyQxgNaEhmIDZZH9vOQIf00-VOQSgMpk8G8GXnAHYKgeTbZlI4KLuzgtCtBQdZgmVGe4/s1600/IMG_20150813_143215849.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFiLOCoHgmjcuw2gLQFdk43ku65_WiQbRnFQddVyj2JiSSWtBOhoU4oDDoLwQm5bKWNCbMSYiUyQxgNaEhmIDZZH9vOQIf00-VOQSgMpk8G8GXnAHYKgeTbZlI4KLuzgtCtBQdZgmVGe4/s320/IMG_20150813_143215849.jpg" width="320" /></a></div>
<span id="goog_1616767044"></span><span id="goog_1616767045"></span>Here's the final assembly. It looked super clean and was ready for a first flight. The radio mount was pretty heavy, but I needed something to protect it. I also didn't have enough room inside the frame to hold it.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgOchDk5slT6JDNM2WfKBhMRkGnfbqGUMQqLkxXfVOEJC4PIAvd4CnW7cOM15IGVLFHhleoeStUDnFZ94xbKw20cVF0b_vHsoM2dgNbH8Xi_z6lRM5Wa0smWeQzy102sqJExIJkLhu7bQ0/s1600/IMG_20150829_130846427.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgOchDk5slT6JDNM2WfKBhMRkGnfbqGUMQqLkxXfVOEJC4PIAvd4CnW7cOM15IGVLFHhleoeStUDnFZ94xbKw20cVF0b_vHsoM2dgNbH8Xi_z6lRM5Wa0smWeQzy102sqJExIJkLhu7bQ0/s320/IMG_20150829_130846427.jpg" width="320" /></a></div>
I quickly discovered that my camera needed to be tipped upwards. When trying to fly quickly the quadrotor tips steeply forward. This means you look more at the ground than what you're flying towards. I could only tip the camera 15 degrees, but this made a huge difference for me.<br />
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I also made a carrying case for all of my equipment. I had the case lying around in my apartment, but it needed foam. I bought some furniture foam (bad choice: too squishy and hard to cut) and made cutouts for everything I needed for a day of flying. <br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEip__H6fYwJewrt421G1pmGNu_LBPNy5HjjOvJCswz3q2AY0Yh3214FgygMf7UUz86vgvXCmcXAqlzrxQbIw9hi2zZYNrJzm-ZGjDKJG-jU87zFhIY5ceGQXa4oWbGnpvHgEL63VLbDFN0/s1600/IMG_20150830_161138474.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEip__H6fYwJewrt421G1pmGNu_LBPNy5HjjOvJCswz3q2AY0Yh3214FgygMf7UUz86vgvXCmcXAqlzrxQbIw9hi2zZYNrJzm-ZGjDKJG-jU87zFhIY5ceGQXa4oWbGnpvHgEL63VLbDFN0/s320/IMG_20150830_161138474.jpg" width="320" /></a></div>
I managed to find a local group of other FPV racers and finally had people to compete with. Unfortunately my riskier flying led to some hard crashes. The video transmitter mount was shattered in one impact. I need to get a less brittle material for the mount parts (or just make them harder to directly hit).<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHeBfYGK8BHyXKKUDP1zqkGc2xc7WbFZygQUPzUDBmpI7qIsfkK9DIcEiX2ozw1Av94HsYo__nusbEppODI8hFxqnjbk0d6MxILFt2GXkbebfIiNL8p6Bbak27O1KC-r8RxVpAq0y3iLQ/s1600/IMG_20150830_175929044.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="900" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHeBfYGK8BHyXKKUDP1zqkGc2xc7WbFZygQUPzUDBmpI7qIsfkK9DIcEiX2ozw1Av94HsYo__nusbEppODI8hFxqnjbk0d6MxILFt2GXkbebfIiNL8p6Bbak27O1KC-r8RxVpAq0y3iLQ/s320/IMG_20150830_175929044.jpg" width="180" /></a></div>
<span id="goog_1616767044"></span><span id="goog_1616767045"></span>I also went through a bunch of propellers. Broken parts start to add up and really increase the cost of the hobby. Thankfully I only broke my 3d printed parts or propellers. The pricey electronics, motors, and frame have all held up well.<br />
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I also discovered the original FPV camera had some latency. This made flying very difficult. I opted to buy one of the popular "board" cameras.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeW9xYxOt8s87rpLre8Z44PRhlvEjvok7UIyjamzRpqZh6O6NDBn4shwUmxRoaQ1IrHYHZ13W4f0GqQcJ1vTsQpZvfMbvulUuam795wXTAGKAXAJHqlABlmj9hzLLFcRzYYfwt_G22LIE/s1600/IMG_20150919_240740025.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeW9xYxOt8s87rpLre8Z44PRhlvEjvok7UIyjamzRpqZh6O6NDBn4shwUmxRoaQ1IrHYHZ13W4f0GqQcJ1vTsQpZvfMbvulUuam795wXTAGKAXAJHqlABlmj9hzLLFcRzYYfwt_G22LIE/s320/IMG_20150919_240740025.jpg" width="320" /></a></div>
<span id="goog_1616767044"></span><span id="goog_1616767045"></span>The new camera left me with more space inside the frame. I was able to sit the video transmitter under the carbon fiber, so I saved a bunch of weight and made the build look significantly sleeker.<br />
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Overall FPV racing has been a fantastic new hobby to get into. It take a fair amount of practice to be competitive with the other racers, but the feeling of flight you get is worth all of the effort. It's like a video game, but much more exciting. Crashing has real consequences (breaking expensive parts), which really gives an adrenaline rush. It's also cool being able to see the real world from a new perspective, something you just can't get in a video game. I still need to get a proper recording camera so I can share my best crashes.JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-53630247936917860752015-07-24T13:46:00.000-07:002017-06-04T17:20:37.085-07:00Cheap Hexapod MechanicsI worked to redesign the hexapod using a more robust set of servos. I concluded plastic gear servos would all fail, so I went with the cheapest full metal gear servos I could find online.<br />
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I bought a number of servos to test. Most of the metal gear servos had one plastic gear inside. I could generally strip the single plastic gear after rapidly back driving these servos by hand. I only managed to find one all metal gear servo in the size I wanted. These came out significantly more expensive than the older plastic gear servos at around $8 each. Even with the increased cost, the hexapod is still significantly cheaper than typical kits.<br />
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Since I got new servos I had to redesign the legs. The original leg design wasn't very elegant, and it didn't take advantage of my 3d printer enough. I redesigned the legs with a more compact collapsing design. In addition, each leg was designed to be fully modular. This gave me more room for an electronics compartment. I also got black resin for my printer. I figured the parts would look more professional if they weren't clear.<br />
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The black resin is very hard to photograph on my white table. The new leg hides the servos much better than the last one. I also through through some of the cable management this time. I even added special conduit in some of the frame parts to keep each wire organized.<br />
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I decided to make the main body a single piece. This ended up being my largest print to date. I'm lucky it finished without any major problems. The surface finish on the parts was starting to degrade at this point. I later (after calling Formlabs support) found a single piece of dust on one of the galvo mirrors (the mirrors that sweep the laser to draw the part) will create a very rough and improperly cured surface. <br />
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The supports had to extend into the part. this made cleanup a pretty big pain. I integrated all nut holders as well as strengthening ribs into the frame. This part was really complex to draw up. I also made sure to fillet as many corners as possible to reduce the likelihood of shattering the parts. </div>
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The first test fit of the parts. It looks like there is a massive amount of room inside the body, however the center hole is the location for the battery and battery cover. I plan to use a small 3 cell (11.1V) LiPo battery. The new body is much shorter than the last hexapod design. The legs also fold up much nicer.<br />
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I printed the top cover (raspberry pi mounts to this) and sealed up the body for the first time. I also added some cable sleeves to the servo wires. Unfortunately these are a pretty big pain to deal with. I decided to skip out on them for the final assembly.<br />
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I finally ordered all of the servos after finishing the full design and checking to make sure the leg was durable and cleanly implemented. The servos have a blue anodized body. The branding is held on my stickers, so I removed them all to make a very clean looking build.<br />
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I also bulk printed the rest of the leg parts. I used a huge amount of printer resin for this project. My desk ended up an unusable mess again...<br />
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After too many hours of assembly I finally completed the mechanics. This thing is pretty massive given the size of my printer. I also love how it is radially symmetric on the outside, unlike the last hexapod design.<br />
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The legs fold up nicely to make a compact frame. The servo wires are left unshielded, but they don't really detract from the aesthetics and shouldn't have any wear issues from rubbing on joints.<br />
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The hexapod gets even bigger when I expand out the legs. It is somewhat hard to make it balance properly without any power on the servos. There is enough gearing to prevent backdriving of the legs if all of the legs are touching the ground.<br />
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The ground clearance is pretty large too. The legs have significantly more range than what is shown. I think I will be able to give this some very life-like animation once I get around to finishing the code.<br />
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The wiring ended up extremely clean. Each servo driver board could handle 16 servos. I only had 18 total, so I split the servos evenly between the two driver boards. This is one of my first projects where I attempted to design for cable management. It really paid off and made the overall build much cleaner.<br />
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I still haven't purchased any batteries for the hexapod, so I run it from a 12V power supply. Everything is controlled and programmed over wifi because the hexpod runs on a raspberry pi. I simply SSH into the os and run everything from the command line. Eventually when I finish the code I'll add in joystick control, but for now I can just enter simple commands.<br />
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Calibration of the legs and most of the testing was done upside down. This prevented the same disaster I had before with the improper walking algorithm. Slamming the entire body weight on one servo due to bad code might break a servo or leg joint. The body weighs enough that it doesn't tip over.<br />
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Here is the first test I ran after calibrating all of the leg servos. I found the end points for each servos travel and matched them between all of the legs. The code now knows the angle a leg points when given a particular PWM signal to a servo. Not every servo responded the same, so I had to do each joint individually. This video shows the full range of each joint.<br />
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The first (and only) walking test I made was a turn in place. My inverse kinematic models seem to work. I will need to make a generalized walking algorithm in the future.<br />
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Overall the new mechanics are leagues ahead of the old design. The newer servos are much more powerful and durable than the old ones, which really justifies the slightly higher cost. I told myself I wouldn't start any new projects until finishing this one. I guess I'm kind of cheating because I made it walk in a circle and I'm calling it "done". I have plans to create a generalized walking algorithm in the future, one that doesn't have predefined gaits. I want the hexapod to walk more like a living creature than a robot.<br />
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<br />JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-12485594630656151222015-04-27T18:42:00.000-07:002017-06-04T17:21:09.303-07:00Guitar Upgrade Parts<div class="separator" style="clear: both; text-align: center;">
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It has been a few years since I built my guitar. I've come to be very annoyed with the shape and weight balance of the body. This comes down to two complaints. First I can't sit with the guitar on one leg like any regular guitar, which makes playing it in a relaxing position a very difficult task. Second I can't play with the guitar while standing up and hanging from a strap. The heavy neck and head had shifted the center of gravity fairly far forward. The guitar tended to tip forward even with the extended front strap mount. <br />
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After thinking about the problem for some time I figured I needed to look at the center of gravity in relation to the two mounting points for the strap. Looking at it now, the CG is obviously going to pull harder on one end of the strap than the other end when hanging in a comfortable playing position. I concluded I needed to make the CG as close to centered between the two strap mounts as possible. I figured friction between the strap and the players neck could tolerate some unbalanced CG.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJZVF4plWvxX5eyGCde_FbUpfCPfTr-41RjvmAAA716n24PbjJgmCGHuy6nR2F6iaJOVJwbVFDL77-6ST0JBYidC282gjzmsdEBCVmfKsa4Jad7Y0A2xRtuzi2oJtW04kK00jIKCCC-oY/s1600/New+CM+12.6lb.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="427" data-original-width="996" height="171" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJZVF4plWvxX5eyGCde_FbUpfCPfTr-41RjvmAAA716n24PbjJgmCGHuy6nR2F6iaJOVJwbVFDL77-6ST0JBYidC282gjzmsdEBCVmfKsa4Jad7Y0A2xRtuzi2oJtW04kK00jIKCCC-oY/s400/New+CM+12.6lb.PNG" width="400" /></a></div>
I designed a new set of side plates for the guitar. These plates differ from the originals in a few ways. First, they're wider than the original plates. This reduces the contact pressure on your leg when playing. Second, they have a concave shape. This allows me to stably rest the guitar on when leg. The concave shape makes it significantly more comfortable to play for extended periods of time. Third, the new plates have more mass in the back. This shifts the CG further back and helps to mitigate the tipping seen in the old design. Finally, The strap mounting points were shifted to be more centered on the CG. I didn't make it perfectly centered, but the strap should hold some imbalance in the weight by friction on my neck.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjp5eVxQxawc-vVBXOjWGLvDpOTeRV4hqJVQADBwq7kgLl6p3WnRqB44JqP_iqbcRPCPpCsBsBbplVs6fDTRo5_UlbnTogyE9HPp7rB8iJDdBAMyEcXEutkru-VR6F2PVB5TzM3raKaEB4/s1600/Guitar+Assembly+2.0+drawing.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="829" data-original-width="1600" height="330" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjp5eVxQxawc-vVBXOjWGLvDpOTeRV4hqJVQADBwq7kgLl6p3WnRqB44JqP_iqbcRPCPpCsBsBbplVs6fDTRo5_UlbnTogyE9HPp7rB8iJDdBAMyEcXEutkru-VR6F2PVB5TzM3raKaEB4/s640/Guitar+Assembly+2.0+drawing.JPG" width="640" /></a></div>
I think the new plate design just looks a lot better than the old ones. I had more input from friends on what looks good / bad as well as ways to fix what doesn't look good.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2g_rDVCSfligfTLs3MR4Zm_Zz7lC_SUUIHlyLw16ueNyuUybXEuwmy1qCtnJ45fQBWY6IZF6cSZKDd8_Mnl3F61AcXLHVx2cPaOUx4ZuV4V0M0u3tPJcMyLm64O7wowLJZoEqrJpr9Pc/s1600/IMG_20160827_134426.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1197" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2g_rDVCSfligfTLs3MR4Zm_Zz7lC_SUUIHlyLw16ueNyuUybXEuwmy1qCtnJ45fQBWY6IZF6cSZKDd8_Mnl3F61AcXLHVx2cPaOUx4ZuV4V0M0u3tPJcMyLm64O7wowLJZoEqrJpr9Pc/s320/IMG_20160827_134426.jpg" width="239" /></a></div>
The upgrade parts really did the trick - I can comfortably play the guitar while sitting or standing. There is still a small amount of weight imbalance when playing while standing, but it doesn't prevent me from using the guitar. The old design was mostly impossible to play when standing up. The bigger side plates did add some more mass to the guitar. The old design was about 10.1 pounds, while the new design is around 12.6 pounds. I think I need to make a new guitar from scratch if I want to drop the weight and get the right weight balance. I think the neck and especially the head really mess up the center of gravity because they are the furthest portions from the body. An easy improvement would be changing the fretboard material to something less dense than stainless steel (titanium or aluminum). Overall I'm pretty happy with the guitar in its current state, and I probably won't get or build a new one for quite a while.JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-80178916810027632112015-03-02T15:28:00.001-08:002015-03-02T15:32:51.837-08:00More Testing - 3D Printed GearsI finally needed to print a functional gear. Driving my RC car in the snow was a bit too much for the main reduction gear (My 3D printed A-arms seemed to hold up fine this time). Snow got into the gear (due to a very poor design that left the gear exposed) and was turned to ice by compression from the pinion gear. The built up ice seemed to push the motor out of the correct meshing distance. The motor then proceeded to grind away most of the teeth.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlmHY19eO6EIjUa3Ra8vi_vHfVnHATJaGWZrePbFc2Xj_CFvreWoh_ZEC9iuSi57LElYtlr-sR9Y7QfbBbhklvI-5IlU6xMvsijEMmdAY8Vcqx5KJhwIbrkEmmGY0Idag5ehjNZzoVAEQ/s1600/IMG_20150214_155545220.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlmHY19eO6EIjUa3Ra8vi_vHfVnHATJaGWZrePbFc2Xj_CFvreWoh_ZEC9iuSi57LElYtlr-sR9Y7QfbBbhklvI-5IlU6xMvsijEMmdAY8Vcqx5KJhwIbrkEmmGY0Idag5ehjNZzoVAEQ/s1600/IMG_20150214_155545220.jpg" height="225" width="400" /></a></div>
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The snow was deeper than this in most spots. I took this picture after the car had already stripped the teeth from the main reduction gear.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiphhevjQV2gCb6iaS99Q8GtYWl7YOnZgM3eAAhW2057K4NPuyL1mqF6NOXRByLeQw4efPk83hF2vOqiHk6i6M9v6uiDyrnwGWcfhrQwaDA6Hg1jCu4LUxqN6vsE-5r1P5tfEexEnB3fqA/s1600/IMG_20150214_155722541.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiphhevjQV2gCb6iaS99Q8GtYWl7YOnZgM3eAAhW2057K4NPuyL1mqF6NOXRByLeQw4efPk83hF2vOqiHk6i6M9v6uiDyrnwGWcfhrQwaDA6Hg1jCu4LUxqN6vsE-5r1P5tfEexEnB3fqA/s1600/IMG_20150214_155722541.jpg" height="180" width="320" /></a></div>
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I put the car in the bathroom to wait for the snow to melt. The electronics avoided the water for the most part, so the only damage done to the car was the stripped gear.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPkjxFw2cMod7f_mPe1UiGCq-XJkP22Wr8Q45b9dv1R24kwxWLWxwk4BoqbXa5EiUTeF9Q2YB2abaOC1lcppxqWntQnmHfcWZK7MDlSI-Whyc7roMWWZ-046falIP6Nft0jsetVa97zrU/s1600/IMG_20150302_180830806.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPkjxFw2cMod7f_mPe1UiGCq-XJkP22Wr8Q45b9dv1R24kwxWLWxwk4BoqbXa5EiUTeF9Q2YB2abaOC1lcppxqWntQnmHfcWZK7MDlSI-Whyc7roMWWZ-046falIP6Nft0jsetVa97zrU/s1600/IMG_20150302_180830806.jpg" height="320" width="180" /></a></div>
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This is the slot in the bottom of the chassis that leaves the gear exposed. The replacement gear is already in the car at this point. I managed to get a face full of gear teeth after a second or two of run time. I didn't have the car on the ground, so the forces on the gear teeth shouldn't have been too high. The gear teeth seem to have shattered. I think this is due to warpage in the gear after it originally printed. The portion of the gear teeth touching the support material had significant warpage. I found this was a problem in my early gear tests, but I decided to try running the gear anyways. I increased the spacing between the pinion and the reduction gear to compensate for the wapage and prevent binding. I also post-cured the gear, which increases the strength and hardness. The post-cure also made the gear more brittle which would explain the shattered teeth.</div>
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<br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPFPqUiUxfr5Lc0GZdV1xGMzERd4y_BmBmjtCke7cBXBPArBsTDwnTizsJV7FtrYcHoIztb_LGJ5MlHuJbKW9WO05GoZgP0PrXug0blIn7cNMkIJgDdLZsBeMBb79mrmB1jvNqm6uwqvw/s1600/IMG_20150302_180853348.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPFPqUiUxfr5Lc0GZdV1xGMzERd4y_BmBmjtCke7cBXBPArBsTDwnTizsJV7FtrYcHoIztb_LGJ5MlHuJbKW9WO05GoZgP0PrXug0blIn7cNMkIJgDdLZsBeMBb79mrmB1jvNqm6uwqvw/s1600/IMG_20150302_180853348.jpg" height="320" width="180" /></a></div>
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It's hard to get a good image of the gear without removing it from the car which takes a while. I didn't want to take apart the car until I had a suitable replacement ready to test.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhczhe9tdsiMSOeW4-uDzhbnCAJh1EE9M1yC-ZaWeEBRxSR_m8dkZ-ndVaWI5ibNBS9mvNqRwqWN3Cu301Z5Vh6IlDY0yALkglKJhNhoUPE-o5bGD8i2IGtlErubQeXNE4JBTZvz5-bFl0/s1600/IMG_20150301_192344995.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhczhe9tdsiMSOeW4-uDzhbnCAJh1EE9M1yC-ZaWeEBRxSR_m8dkZ-ndVaWI5ibNBS9mvNqRwqWN3Cu301Z5Vh6IlDY0yALkglKJhNhoUPE-o5bGD8i2IGtlErubQeXNE4JBTZvz5-bFl0/s1600/IMG_20150301_192344995.jpg" height="180" width="320" /></a></div>
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I tried printing with my black resin instead of the clear resin. I had hoped the black resin would have less warpage than the clear resin.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWiFKuAG0tTzp1viFQVh39rGM990YTaFxS1Bcp4D79qz7XBZyoijN_h8UOQY-BPlIMHMrO9UhyphenhyphentAqM6JlP1m2R6euuhvwwZqORgzgHo1yZkM9J9lkLlyP3P2zY2ucC7uv5ooEHNJU6DBo/s1600/IMG_20150302_173554337.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWiFKuAG0tTzp1viFQVh39rGM990YTaFxS1Bcp4D79qz7XBZyoijN_h8UOQY-BPlIMHMrO9UhyphenhyphentAqM6JlP1m2R6euuhvwwZqORgzgHo1yZkM9J9lkLlyP3P2zY2ucC7uv5ooEHNJU6DBo/s1600/IMG_20150302_173554337.jpg" height="180" width="320" /></a></div>
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The gear in the bottom left is the original gear. The bottom right is my new replacement gear printed in the black resin. The top two gears are spares that I printed, but didn't release from the support material.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiz13hlm33B7FtCw_RQv6Yd3NaAW-8S28KWt6vRrIXyoC8uYlZ6qXPpwb0DQp2oWPApdUzZwdi22rEnz9cRgYoB027tqvxl8aTLqyYVEGNK-miMdLQPdLzjPLaOAySc8r8BiCR13_GMkr0/s1600/IMG_20150302_173734467_HDR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiz13hlm33B7FtCw_RQv6Yd3NaAW-8S28KWt6vRrIXyoC8uYlZ6qXPpwb0DQp2oWPApdUzZwdi22rEnz9cRgYoB027tqvxl8aTLqyYVEGNK-miMdLQPdLzjPLaOAySc8r8BiCR13_GMkr0/s1600/IMG_20150302_173734467_HDR.jpg" height="320" width="180" /></a></div>
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I used a machinists square to visualize the warpage on the gear teeth. The majority of the gear has gear teeth that are square to the faces of the gear, however a small portion (~20%) has slanted teeth like these. This makes it impossible to have a proper gear spacing without binding. I will keep trying different orientations and possibly different gear geometry to avoid this waparge, but for now I may have to order a replacement set of gears for my RC Car.<br />
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<br />JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-21402910800784067502015-02-01T21:48:00.001-08:002015-02-01T21:49:45.155-08:00New Project (Finished too) - Computer Charger Repair<div class="separator" style="clear: both; text-align: left;">
The output wire from my laptop charger frayed and shorted about a year ago. The wire was built into the charger and broke right where it came out of the charger. I couldn't do without my laptop so I had to get a new charger. I kept the broken one so I could repair it and have a spare at some point. There wasn't enough wire left out of the charger to simply solder the cable back together, so I knew it would need a full case replacement. I also wanted to add a second connector so I could remove the output cable and a similar break in the future.</div>
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The charger appeared to be one solid piece of plastic. There were no seams or obvious places to try prying the charger apart. I managed to chip away the rubber that sealed the output cable to the charger. The small opening let me look inside and determine the wall thickness of the charger's case. I could also see the orientation of some of the internal components. I guessed the circuit board was inserted right-side-up into the charger during assembly which led me to guess which side was the lid.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEio1RRic6ktktlfhc2Gp9wsChmfTWGi8KDPNyGghKNjzSez4vbR5E0U0W8scZ0Iaynjx6x28E9y1mob6vlJWCRZyn9kxL6H7BehH-C4qbeyiSpP4VimlfRQ5WY4VUpha6rdI0f1wUkn4qU/s1600/IMG_20140419_160740_537.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEio1RRic6ktktlfhc2Gp9wsChmfTWGi8KDPNyGghKNjzSez4vbR5E0U0W8scZ0Iaynjx6x28E9y1mob6vlJWCRZyn9kxL6H7BehH-C4qbeyiSpP4VimlfRQ5WY4VUpha6rdI0f1wUkn4qU/s1600/IMG_20140419_160740_537.jpg" height="240" width="320" /></a></div>
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I used a mill to cut away just the outer wall of the charger. I stepped down a small amount with each pass until the top lid broke free. It turned out to be held in with plastic snaps. I believe the lid was glued or friction welded to the rest of the case. It was a clean, but unrepairable design. I managed to avoid cutting any of the components.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzBTMEduMGphjTPitVz8Ao4ghZqosEilV624iBcU-DVzdUnNjycBGda5rmE6_80ddflINUVVtVFA0zUoCrv3ppm_ff3qr0SEtyKLu7QWSJnHnN8vSeDsjwG1GWoCwGNOq_fyiICgCdcQ4/s1600/IMG_20140419_212301_767.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzBTMEduMGphjTPitVz8Ao4ghZqosEilV624iBcU-DVzdUnNjycBGda5rmE6_80ddflINUVVtVFA0zUoCrv3ppm_ff3qr0SEtyKLu7QWSJnHnN8vSeDsjwG1GWoCwGNOq_fyiICgCdcQ4/s1600/IMG_20140419_212301_767.jpg" height="240" width="320" /></a></div>
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The charger had pretty simple internal geometry. I reversed engineered the critical geometry in the case to hold the remaining components.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFQKD-eoidBU1b5wHfmHmwlJO3KI8Nm6r9CUjo6BOekM1zL9Q3eosIKJm1G49m8tPv6GE5LKOz0qYN-i59xHmgDf6Bh9LnoAvuO-Guw-XwUwbb71suhH6kNOEXE04w2MumUDU8zUHUlN8/s1600/Surface+Charger+Repair+Case+Assembly+1.0.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFQKD-eoidBU1b5wHfmHmwlJO3KI8Nm6r9CUjo6BOekM1zL9Q3eosIKJm1G49m8tPv6GE5LKOz0qYN-i59xHmgDf6Bh9LnoAvuO-Guw-XwUwbb71suhH6kNOEXE04w2MumUDU8zUHUlN8/s1600/Surface+Charger+Repair+Case+Assembly+1.0.JPG" height="163" width="320" /></a></div>
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I bought a pretty nice looking connector without looking at the dimensions... The connector wasn't going to fit in the original case geometry, so I was forced to put it on the lid. I'll admit its a strange form for a charger, but it worked out. I originally planed to use the black resin on my 3D printer to make it look nice, but I got lazy and used the clear resin that was already in my printer.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiq9CfTorI9_vtcAnhzVFZp_VXjnnKLdMp5iuwwmZQ4BkMYC3OoUOXiliVPV0g8HAhNl_WpW9BaNrvGTt6kkTrFcHXe5HYKrsc_6x3J2z0jPEdR2OFENfSru3iuX6Zoza4199SetKbb2xA/s1600/IMG_20150201_020148386.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiq9CfTorI9_vtcAnhzVFZp_VXjnnKLdMp5iuwwmZQ4BkMYC3OoUOXiliVPV0g8HAhNl_WpW9BaNrvGTt6kkTrFcHXe5HYKrsc_6x3J2z0jPEdR2OFENfSru3iuX6Zoza4199SetKbb2xA/s1600/IMG_20150201_020148386.jpg" height="320" width="180" /></a></div>
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Here is the main part of the case after it came out of the 3D printer. This is probably the largest part I've printed so far. Thankfully it didn't have a print failure like I had with a few other parts recently.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSX4XdTdRw1xdy_lsAfWtzJ_PKnIbBAecTe2uhBWJ5ul8PlXLFP1I3-Mwg_0MSlSu_RPDQsAOe7yHO-aC1TEebFPYR56QIjWjMjIlttViius0Ei9MMM95S2j99SxZ-RTcSjMKt3EIP8ZE/s1600/IMG_20150201_201344314.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSX4XdTdRw1xdy_lsAfWtzJ_PKnIbBAecTe2uhBWJ5ul8PlXLFP1I3-Mwg_0MSlSu_RPDQsAOe7yHO-aC1TEebFPYR56QIjWjMjIlttViius0Ei9MMM95S2j99SxZ-RTcSjMKt3EIP8ZE/s1600/IMG_20150201_201344314.jpg" height="180" width="320" /></a></div>
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The lid also printed cleanly. As usual the extra material for the support felt like a waste, but there isn't much I can do to avoid adding it.</div>
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I wanted the charger to be symmetrical, so I put screws on the bottom. They don't hold anything together, but they do look nice.</div>
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The charger fit snugly into the case. The wall power plug even fit into the case!</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHq255f6NJLA5I37VBN8TSDwCyyR52gf5nf8ovs_H0rJP5oMjseMCJjme-UlRaHFmGboLtpnVm_JxwO7GPZDfpspq2ylD_ELOjLWP6nNwx8LASFcMpqaM7_mn0K_yFOaPPmwG5_4rUCvo/s1600/IMG_20150201_204306465.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHq255f6NJLA5I37VBN8TSDwCyyR52gf5nf8ovs_H0rJP5oMjseMCJjme-UlRaHFmGboLtpnVm_JxwO7GPZDfpspq2ylD_ELOjLWP6nNwx8LASFcMpqaM7_mn0K_yFOaPPmwG5_4rUCvo/s1600/IMG_20150201_204306465.jpg" height="180" width="320" /></a></div>
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Here's the lid before squishing the remaining wires into the charger.</div>
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The charger has been revived! The design is pretty strange, but it's functional which is what counts. The upward angle output plug is actually nice because it reduces wire stress when reaching from the floor to a table. It also makes the USB charging port easier to access. I should have been less lazy and printed the charger case in black, but at least the insides are visible like one of the old clear gameboys.</div>
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<br />JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-54054112802945804642015-01-16T21:07:00.000-08:002015-01-30T19:28:39.085-08:00RC Car Replacement Parts<div class="separator" style="clear: both; text-align: left;">
This time the rear A-arms on the RC car broke. I may no longer have access to a milling machine, but now I have a 3D printer. I modified the CAD for the front A-arms and had a set of rear A-arms printing in a few hours. These parts took a mere 5 hours to print. They could have taken less time, but I decided to try printing with the high layer resolution setting (0.025mm per layer). I also tried printing the parts directly on the table. Technically this is frowned upon with this printer, but the parts came out mostly fine. It saved a ton of support material, so I can live with any defects caused by printing directly on the table.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhit-bJpgGXBJ2Ld6Z0Z9JcyGGe9E9wauQr6RBYylvUXSQzsAbd83vjRf4wWI6adSgJH8IiBjFy3QV7e-GOc-0HrpQOCH8XuF-XQOlipeP4IQBYP0qdUtbxUpc0CdZbJSXIAa4lNJbVmng/s1600/IMG_20141022_190248_906.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhit-bJpgGXBJ2Ld6Z0Z9JcyGGe9E9wauQr6RBYylvUXSQzsAbd83vjRf4wWI6adSgJH8IiBjFy3QV7e-GOc-0HrpQOCH8XuF-XQOlipeP4IQBYP0qdUtbxUpc0CdZbJSXIAa4lNJbVmng/s1600/IMG_20141022_190248_906.jpg" height="240" width="320" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMZ_RcXxQDvfPGYrBwtbLFhsUzBJqHeM0wSWN5IQzG9Gi4LeVbkvBqpvEJgGo2Slga0jOo8lLKETBD4jGmz1GpfNdDWXJm9A4A0cY9d-SC1OxKWaQKbJmWM7Y0zNHoJcN1Phc_7-Apl2k/s1600/IMG_20141125_230649_740.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMZ_RcXxQDvfPGYrBwtbLFhsUzBJqHeM0wSWN5IQzG9Gi4LeVbkvBqpvEJgGo2Slga0jOo8lLKETBD4jGmz1GpfNdDWXJm9A4A0cY9d-SC1OxKWaQKbJmWM7Y0zNHoJcN1Phc_7-Apl2k/s1600/IMG_20141125_230649_740.jpg" height="480" width="640" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheDJVrAUZXNpoTnINdXKmX2-CE-BTClhqH2W0FZIER5HLp5_XoKfIZaNd4ZIJ-KfHgWwi761WxQva35kIp0NhhzTee9Hb5vsEkK2pHYpSe_pA5xT_th_0NtV2h3I0guKKbgKYDg_X8LQQ/s1600/IMG_20141125_230705_680.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheDJVrAUZXNpoTnINdXKmX2-CE-BTClhqH2W0FZIER5HLp5_XoKfIZaNd4ZIJ-KfHgWwi761WxQva35kIp0NhhzTee9Hb5vsEkK2pHYpSe_pA5xT_th_0NtV2h3I0guKKbgKYDg_X8LQQ/s1600/IMG_20141125_230705_680.jpg" height="480" width="640" /></a></div>
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The car looks pretty slick with all these custom parts!<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9QwN7Q6CYLgRp2o9J4UZbrTx3Sdf0cNqMbGcnul1tlqwrjJ_rDl79ob8kybT3-Xr_dAN106iCw9lHdrXO_614vwDFu_5_2UGoKdWRCXAY_ejcQ9N0dsisYqmZzqyd4s59atYJIfI0dFo/s1600/IMG_20141125_230804_399.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9QwN7Q6CYLgRp2o9J4UZbrTx3Sdf0cNqMbGcnul1tlqwrjJ_rDl79ob8kybT3-Xr_dAN106iCw9lHdrXO_614vwDFu_5_2UGoKdWRCXAY_ejcQ9N0dsisYqmZzqyd4s59atYJIfI0dFo/s1600/IMG_20141125_230804_399.jpg" height="240" width="320" /></a></div>
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I also added the shock spring mounts. These prevent any binding between the shock and the replacement A-arms.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7WtqhnDS0n3uBPZyAhS0H4r79iFrssmnqwfmpBaUPSuritrgRA83i9gIjIiHqhV96dI97XSGkdvV_NC5rCtRXTqGdSlX7bPbWWljmtSPFQmOOQA0OVAbDVxk40tTLFG1Ig89thPTCDQg/s1600/IMG_20150115_185947317.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7WtqhnDS0n3uBPZyAhS0H4r79iFrssmnqwfmpBaUPSuritrgRA83i9gIjIiHqhV96dI97XSGkdvV_NC5rCtRXTqGdSlX7bPbWWljmtSPFQmOOQA0OVAbDVxk40tTLFG1Ig89thPTCDQg/s1600/IMG_20150115_185947317.jpg" height="320" width="180" /></a></div>
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Unfortunately... I went too hard with the car shortly after making the new parts...<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1_XS5LoBRFg5IbGRlqhfZsxb_oCyjksNqt6R33X4HWNdJJnNeYdUpOnkaM5z1hj4dP3JHEckeXwOdcn8wgrCsJQuSK7bQDCc0sHa0upoE14Hy55pF4D34kVy-6CqEMp7_KgBLnD8jSS0/s1600/IMG_20150116_144242009.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1_XS5LoBRFg5IbGRlqhfZsxb_oCyjksNqt6R33X4HWNdJJnNeYdUpOnkaM5z1hj4dP3JHEckeXwOdcn8wgrCsJQuSK7bQDCc0sHa0upoE14Hy55pF4D34kVy-6CqEMp7_KgBLnD8jSS0/s1600/IMG_20150116_144242009.jpg" height="320" width="180" /></a></div>
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My replacement shock spring mounts took up more space than the originals. This prevented the shock from reaching its end stopper. The end stopper is an internal piece of rubber that prevents the piston from bottoming out and smashing into hard plastic. The car hit a hard landing after a jump and slammed hard plastic into hard plastic. The 3D printer parts can be post cured (which I did). The post curing greatly hardens the plastic, but also makes it more brittle. I won't do that with a future set of A-arms.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2zK0X8lpAG-rNwsizZMZUHx1TEMkcljsqf2KaIeXXhJOpsPHtBM9sVxY9WJaJYF3iJmZ9833mJC7uAUHVATTx9O7oajtXY_dQKuhEFtaXcbTe_IdIO1gPy_LdW0ucATU-f9PU66ZG8bk/s1600/IMG_20150116_144323642.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2zK0X8lpAG-rNwsizZMZUHx1TEMkcljsqf2KaIeXXhJOpsPHtBM9sVxY9WJaJYF3iJmZ9833mJC7uAUHVATTx9O7oajtXY_dQKuhEFtaXcbTe_IdIO1gPy_LdW0ucATU-f9PU66ZG8bk/s1600/IMG_20150116_144323642.jpg" height="180" width="320" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFA0eLgh4M54yS8YDMtrAX52Qn-EdXW7yTbMwHo540z1R4mGADMpg1BnIPUDpfqRyoTSiyVMtLi1Ijeu1Ur4yQnHCx9m9VnYMTOqohvv-avcISDDqaWfynNTgmh9qfpfBbk8kr-kc_BHc/s1600/IMG_20150116_144407095.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFA0eLgh4M54yS8YDMtrAX52Qn-EdXW7yTbMwHo540z1R4mGADMpg1BnIPUDpfqRyoTSiyVMtLi1Ijeu1Ur4yQnHCx9m9VnYMTOqohvv-avcISDDqaWfynNTgmh9qfpfBbk8kr-kc_BHc/s1600/IMG_20150116_144407095.jpg" height="180" width="320" /></a></div>
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I'm starting to learn the material limitations from the 3D printer. The resin cures to be a somewhat brittle plastic. I have been post curing all of my parts (exposing them to additional UV) to make them harder. The parts that come out of the machine can be somewhat flexible and have a soft surface. The gears I've made need to be hardened or they will wear out quickly. This application of the plastic is better soft and slightly weaker. The added flexibility lowers the forces on the parts and prevents shock loading. I'll also look into making certain portions of the A-arm thicker. Holes - especially tapped holes become stress concentrators. These create points where a crack can propagate and make the part considerably weaker.JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com1tag:blogger.com,1999:blog-4585776524802028435.post-10408531965570319392015-01-13T21:37:00.000-08:002015-01-30T19:25:34.383-08:00Test - 3D Printed Gears<div class="separator" style="clear: both; text-align: left;">
One of my goals for the 3D Printer was fast and cheap production of gears. Buying plastic gears can be expensive and they often require modifications. This can waste a ton of time. In addition, they might not be the exact number of teeth required for a project. I decided to test the 3D printer and determine what settings and orientations were best for high quality parts.</div>
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I started off by printing some 64 pitch gears. I was curious to see if the printer was capable of making these parts. The results were pleasantly surprising! All of these close up shots were taken with my phone. I hacked together a macro lens using a thumb sized magnifier. I taped the lens over my camera and got a 10x zoom! The only down side is there is a fair amount of distortion over the images. However, it reveals details that the camera or my own eyes couldn't see alone.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMq4NNaO6FdWa0MPDn80_l-Z8Xi1goZSUdPy_WUdERUyhEhPY63dNluK7AcooGNWrk04X2YYbr3QLfVMuUyBs904X2aiVl54I2RQNHN17pA1n9kAjuYx5F2YHmpuQ_19NsfyF8EqiVZsc/s1600/IMG_20141101_221555_506.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMq4NNaO6FdWa0MPDn80_l-Z8Xi1goZSUdPy_WUdERUyhEhPY63dNluK7AcooGNWrk04X2YYbr3QLfVMuUyBs904X2aiVl54I2RQNHN17pA1n9kAjuYx5F2YHmpuQ_19NsfyF8EqiVZsc/s1600/IMG_20141101_221555_506.jpg" height="240" width="320" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCiIewzsJgSStpkryGwk3bt4dCe2Z-Z6YE-RXb8JHbIruj0rbdidJpemDIOQneV9YWpZecmBvIdhZmrhPL4WATJk1tP_jq_Iy-Pcs-RDRYBL2QPv6-2DKeG0UEo-09U2rZntvwiczRevk/s1600/IMG_20141101_221703_108.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCiIewzsJgSStpkryGwk3bt4dCe2Z-Z6YE-RXb8JHbIruj0rbdidJpemDIOQneV9YWpZecmBvIdhZmrhPL4WATJk1tP_jq_Iy-Pcs-RDRYBL2QPv6-2DKeG0UEo-09U2rZntvwiczRevk/s1600/IMG_20141101_221703_108.jpg" height="240" width="320" /></a></div>
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This is one of my first test prints of a 64 pitch gear. There is some surface roughness that can be seen on the gear, but all of the teeth seem to have a reasonable profile. This gear was printed in the coarsest layer height (0.1mm per layer). The layers don't seem to create "steps" in the teeth.The surface roughness is still pretty good even though the layers are visible<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8dOgiQVyY6sZLHPM8AotO54mrfYbomm7HrdyMnjmlA-FTdWoUGl_Bjzf0o6rPHkJDSgEBa_3Ai2nqhrmZyBBWoGSpZApP-iaUoWTq47D65ecdgByNVZwCUnqdCFGuwzIS59bWXMszc-E/s1600/IMG_20141102_010636_596.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8dOgiQVyY6sZLHPM8AotO54mrfYbomm7HrdyMnjmlA-FTdWoUGl_Bjzf0o6rPHkJDSgEBa_3Ai2nqhrmZyBBWoGSpZApP-iaUoWTq47D65ecdgByNVZwCUnqdCFGuwzIS59bWXMszc-E/s1600/IMG_20141102_010636_596.jpg" height="480" width="640" /></a></div>
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This is a picture that just looked cool. I have no idea what happened with the focus of the camera but it added some neat effects. This gear was printed on the highest layer resolution (0.025mm per layer). Here the layers can't be seen. It just looks slightly opaque.<br />
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Here is a side by side comparison between the course and fine layer resolutions (0.1mm and 0.025mm per layer respectively). Both gears seem to have reasonable tooth profiles. It is hard to tell whether there is warpage in the teeth as the lens created considerable distortion in the picture. The lens also created a very shallow depth of field so only portions of the gear are in focus at once.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2ruA8Zzu9xDHGfixY-falZQ3SxObTG-iRywFUGPttbdAvkQtcNN7AD68rYJpe5LIH67yjffsk7abqj8yi0IqOkAQ_Hi5S20nkLdNXPDeQOKR1vVvA5u7LEaxx1d0kxJjN_NnYKySmywE/s1600/IMG_20150129_211336430.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2ruA8Zzu9xDHGfixY-falZQ3SxObTG-iRywFUGPttbdAvkQtcNN7AD68rYJpe5LIH67yjffsk7abqj8yi0IqOkAQ_Hi5S20nkLdNXPDeQOKR1vVvA5u7LEaxx1d0kxJjN_NnYKySmywE/s1600/IMG_20150129_211336430.jpg" height="180" width="320" /></a></div>
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I also worked on larger gears. The majority of these gears are 32 pitch - 40 tooth gears. I wanted to see how different orientations of the gears in the printer would cause different amounts of warpage on the overall shape. I also wanted to see how various levels of post curing reduced wear on the gears. I also printed a set of 20 pitch - 25 tooth gears. All of the gears meshed fine, however some warpage in the gears led to noticeable wobble on the shafts. I found increasing the resolution and adding more supports during the printing helped to mostly eliminate these issues. I'll have some projects coming soon that will be built off of these gears. There is also a cluster gear in this photo that contains a timing belt pulley in addition to a 32 pitch gear. This part couldn't be made through traditional machining techniques, so I'm very excited to see what unique structures I can design and build with the 3D printer.</div>
<br />JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-16775863219430827282015-01-09T16:30:00.000-08:002017-06-03T13:43:44.517-07:00New Project - Cheap Hexapod<span id="goog_1616767011"></span><span id="goog_1616767012"></span><div class="separator" style="clear: both; text-align: left;">
I've always wanted to build a Hexapod. They look pretty cool with all of the legs moving in sync. They can also be used as a desktop toy, unlike my RC car, which is basically an outside only toy. The biggest problem with hexapods is they are really expensive. A proper hexapod requires three degrees of freedom for each leg. This ensures that the leg doesn't need to slide on the ground. The three degrees of freedom per leg and six legs require a hexapod to have at least 18 servos. The servo cost adds up fast and had previously discouraged me from building a hexapod. Recently I came across micro sized servos (HXT900 9g servos). These servos cost about three dollars each. Even with 18 servos that still isn't too expensive compared to typical on brand servos that cost about 20 dollars each.</div>
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I wanted to build the hexapod around my new 3D printer. The first thing I decided to do was integrate the servo splines into the legs themselves. After a number of test prints I was able to confirm it is possible to create micro size servo splines with my 3D printer (Form1+). I also wanted to keep the design minimalistic and avoid over complicated joints and leg segments.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0c53_sgRvV2aleXDf7ZssbcAnyDEy6ztQfOsLA9q1XlYSKZiIFVJzGSZsYQD9yJwwGWeP6kHRu1V2as_TQa9XRTtXcgrfyVB7n9XrWYctLBmWve35VgYMBpdDQPbC4Njo7UOM_IXAdxQ/s1600/IMG_20141125_231218_331.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0c53_sgRvV2aleXDf7ZssbcAnyDEy6ztQfOsLA9q1XlYSKZiIFVJzGSZsYQD9yJwwGWeP6kHRu1V2as_TQa9XRTtXcgrfyVB7n9XrWYctLBmWve35VgYMBpdDQPbC4Njo7UOM_IXAdxQ/s1600/IMG_20141125_231218_331.jpg" width="320" /></a></div>
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I bought three servos before I committed to building the hexapod. I printed and assembled one leg to ensure the servos would be strong enough to drive the leg. I also wanted to test the tolerances on the servo splines with multiple servos. This image shows the leg prototype, The only change I made to the leg design was an increase in the depth of my logo.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcN-ICVJfAQhlIJupX9TVqaeCujs4I23QZHUXr6YXQVCXTj2DgcqRCnlevfvyY8O4imSOkGIVmaBCRs30JbxqfBW0PzTUcKvaj6iWC84QiKtkramXFkSKlJrZ4iNL9BMlXLinHRSZkqDI/s1600/IMG_20141214_135246470.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcN-ICVJfAQhlIJupX9TVqaeCujs4I23QZHUXr6YXQVCXTj2DgcqRCnlevfvyY8O4imSOkGIVmaBCRs30JbxqfBW0PzTUcKvaj6iWC84QiKtkramXFkSKlJrZ4iNL9BMlXLinHRSZkqDI/s1600/IMG_20141214_135246470.jpg" width="180" /></a></div>
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This was the first "production" run for my 3D printer. I had to make six copies of each leg part as well as the body section. Aside from one print failure (on the main body servo mount plate) everything printed perfectly. I literally couldn't make these parts through machining given the orientations of the splines and the shapes of the parts.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_4nN63q32a00gLBUrxfcYefiJoudtH2gkFmnBHMCVX4-C3xHGe9CQjinr1rzJZ7TnuGKBCd1zpjTY4MT20fMZ8JkTIckeisWbpg_WYjSQQjHMMvZfydvyrmvVCMi6EPLaxDob3XPvIDI/s1600/IMG_20141217_025829171.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_4nN63q32a00gLBUrxfcYefiJoudtH2gkFmnBHMCVX4-C3xHGe9CQjinr1rzJZ7TnuGKBCd1zpjTY4MT20fMZ8JkTIckeisWbpg_WYjSQQjHMMvZfydvyrmvVCMi6EPLaxDob3XPvIDI/s1600/IMG_20141217_025829171.jpg" width="320" /></a></div>
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This is the body piece ( the one that printed correctly) as it came off of the printer. There was an update to the printer software that dramatically reduced the material wasted in the support structure for the parts.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivNBJED4pDxLXxo2dGRyNEfVvFSLql3SgpJV0xhyx07ld1x5bVZMCZrA7sk6G98dvAJzoKIpSrjFe1bU8h3kKJ8Ibh4QoYcdvnfJ2zHBk46cW7ceNFqk2fUhHU2b_5lBupHjf-MH7SeZU/s1600/IMG_20141217_044703738_HDR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivNBJED4pDxLXxo2dGRyNEfVvFSLql3SgpJV0xhyx07ld1x5bVZMCZrA7sk6G98dvAJzoKIpSrjFe1bU8h3kKJ8Ibh4QoYcdvnfJ2zHBk46cW7ceNFqk2fUhHU2b_5lBupHjf-MH7SeZU/s1600/IMG_20141217_044703738_HDR.jpg" width="320" /></a></div>
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Here is the part before support material removal. The supports are removed with wire cutters and then the remaining bumps on the part surface are removed with a file.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDyOFBLPLr5l1nRoPS5-eHiRCRhjzslS9IXufjwiEWurSOTyOMJhZ8tewoIc24pHkXW15NkWnXWKmvc6H7t4z34F2WKVdnSThFChcREZLpPkdmvcscQr5JhchhwRAux1vTDXLFZe_d-SU/s1600/IMG_20141218_190427014_HDR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDyOFBLPLr5l1nRoPS5-eHiRCRhjzslS9IXufjwiEWurSOTyOMJhZ8tewoIc24pHkXW15NkWnXWKmvc6H7t4z34F2WKVdnSThFChcREZLpPkdmvcscQr5JhchhwRAux1vTDXLFZe_d-SU/s1600/IMG_20141218_190427014_HDR.jpg" width="320" /></a></div>
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The final part looks pretty clean. All of the dimensions seem to be within tolerance for the hexapod. There is some warpage in the part that occurred after the post curing, but it shouldn't prevent the part from being usable.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4QkkU2IJ0x5RL7NZ-W5RSPBlvPxryjAQTBX-52-fN8FRZ-1iszcICLdAM5bMKYp9zHTfnRNCLQ9Di0v_ydSsK3QlWgRGO0kSflZPUbQm8npWdhUm7d3mbpUwnLNsCrez4OPB4IHRbBRM/s1600/IMG_20141218_192515017_HDR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4QkkU2IJ0x5RL7NZ-W5RSPBlvPxryjAQTBX-52-fN8FRZ-1iszcICLdAM5bMKYp9zHTfnRNCLQ9Di0v_ydSsK3QlWgRGO0kSflZPUbQm8npWdhUm7d3mbpUwnLNsCrez4OPB4IHRbBRM/s1600/IMG_20141218_192515017_HDR.jpg" width="320" /></a></div>
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Each servo requires two 2-56 screws to be threaded into the frame. My hand got pretty tired trying to screw all of the servos into the mounting plate. Each servo fit nicely into the plate.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3Y_D70-DQh9NJFp69lKtTWcYYKMxMer_x39BN-mh3DN_QNKgJSr-javZAvW_odTGWuKFmU4kF6n0E47V1tNg6gxBpNi6DnSD2ZhV8ogD0Qi5yxGM-xCoMjcxsSxBha1r_WqhJSWzjmmw/s1600/IMG_20141218_230358600_HDR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3Y_D70-DQh9NJFp69lKtTWcYYKMxMer_x39BN-mh3DN_QNKgJSr-javZAvW_odTGWuKFmU4kF6n0E47V1tNg6gxBpNi6DnSD2ZhV8ogD0Qi5yxGM-xCoMjcxsSxBha1r_WqhJSWzjmmw/s1600/IMG_20141218_230358600_HDR.jpg" width="320" /></a></div>
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I decided to try fitting all of the pivots into the lower central support plate. It was fun getting to see the hexapod come together.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCBJFuMcT35bp5fYINp_3Tag1FUqxeFEgrF5R8n9vuhCTSvElxgGz8NCEfWJDpHEG-Cz-GKtspEwyfL7XaT0dSqIX6eTtevIHpq8pLlDIxjodId9I2QcsANzP_-aLjXl9oiwwiDGssLjw/s1600/IMG_20141219_012059721_HDR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCBJFuMcT35bp5fYINp_3Tag1FUqxeFEgrF5R8n9vuhCTSvElxgGz8NCEfWJDpHEG-Cz-GKtspEwyfL7XaT0dSqIX6eTtevIHpq8pLlDIxjodId9I2QcsANzP_-aLjXl9oiwwiDGssLjw/s1600/IMG_20141219_012059721_HDR.jpg" width="320" /></a></div>
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This was the first time the hexapod was fully assembled. I knew the wiring would be an issue, but I didn't realize how messy the hexapod would look without proper wire management.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-OsDllo0ZM8SDBl8KJw1qGpj30cMoFrIWzPWrR6YllZBI6zMBLnzcuwyZPPL8KECWBx2C4fWhdFzscVodZCUB4qHzY6MpOfDxednND-i3FXKDbo2es6BUag_RJT0jbq5M2Z1ZElP3s-A/s1600/IMG_20141220_211910644.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-OsDllo0ZM8SDBl8KJw1qGpj30cMoFrIWzPWrR6YllZBI6zMBLnzcuwyZPPL8KECWBx2C4fWhdFzscVodZCUB4qHzY6MpOfDxednND-i3FXKDbo2es6BUag_RJT0jbq5M2Z1ZElP3s-A/s1600/IMG_20141220_211910644.jpg" width="320" /></a></div>
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Here is my programming testing setup. I was at my house for the winter break and no longer had access to my 3D printer. I had CNC access but I didn't particularly want to get covered in chips as I usually do when machining. I used a raspberry pi model a+ as the controller. This raspberry pi is the smallest one currently available. I wanted to run the hexpod with linux and python because it makes the programming easier. The hexpod currently connects to a computer over wifi which was really easy to do and should be a convenient way to control the hexapod. The two blue boards are PWM driver boards from adafruit. Each board can drive up to 16 servos ( I needed to drive 18 so I had to get the second board). The boards are controlled with an I2C interface. This means I need a minimal number of pins from the raspberry pi to control all of the servos. It helps to keep the wiring from being a mess.</div>
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Here is an early motion test. I programmed the legs to look like they were walking. I still needed to calibrate each servo and complete the actual leg motion program. This shows the hexapod moving its legs near the peak servo speed.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjS0g21PLiBSiW0rSQNLJ6pHohYk9k9m-AXbjhjA4tvq611Vcs4cqaT91F7q7vBDd8TwNWYfDywsBqroYTNFDnpdSfJwNlXyBITUlUlzRpdfuBOXgsSvfZfz_ejx9EtfrJbSlB4C4Uh0r4/s1600/IMG_20141225_210006291_HDR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjS0g21PLiBSiW0rSQNLJ6pHohYk9k9m-AXbjhjA4tvq611Vcs4cqaT91F7q7vBDd8TwNWYfDywsBqroYTNFDnpdSfJwNlXyBITUlUlzRpdfuBOXgsSvfZfz_ejx9EtfrJbSlB4C4Uh0r4/s1600/IMG_20141225_210006291_HDR.jpg" width="320" /></a></div>
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This was the first PCB I milled on a proper milling machine. I've always had access to a dedicated PCB mill, so coming up with my own milling procedure was fun. I drew the circuit board in SolidWorks so it would be easy to generate the G-Code for the CNC. A proper circuit CAD program like eagle probably would have been a better choice.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4umEgjmLDNxwvGiVsRlcflVvgsSsxDgR6tbMCz1w4WHgG3-L1fuWYwiKhrAgFVjyWpOqXATKiHqQpVz0KjYc_hjL6mnPJUFe2rUeW5fGjJWTHCRPtym1BvS7bj6hXakBisFOoXHGRgLo/s1600/IMG_20150129_204405432.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4umEgjmLDNxwvGiVsRlcflVvgsSsxDgR6tbMCz1w4WHgG3-L1fuWYwiKhrAgFVjyWpOqXATKiHqQpVz0KjYc_hjL6mnPJUFe2rUeW5fGjJWTHCRPtym1BvS7bj6hXakBisFOoXHGRgLo/s1600/IMG_20150129_204405432.jpg" width="320" /></a></div>
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The PCB I milled was for the hexapod's power supply. This supply is capable of driving up to 20A at 5.5V. I wanted to drive the hexapod with a 7V battery, but the servos and raspberry pi wanted 5V. Each servo doesn't draw very much current, however the combination of all 18 which could all be running at full torque at one time would overwhelm most power supplies. I decided to go with the 20A supply to ensure there would never be a sever voltage drop that could shut down the raspberry pi.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9-xTeyeVVWfZHYs9omoWZ3RD9x1o1kQhpapq4V_Z2ECpoLtcFgJMhOKKbpliCMIaq0SkhXY0KBSXWfdQU38AuKQ8FdOQXuO944VzfXiBt6xwODZ1HDpSp8U22rVq-mL52ayXGcCVjdeg/s1600/IMG_20141227_243419368.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9-xTeyeVVWfZHYs9omoWZ3RD9x1o1kQhpapq4V_Z2ECpoLtcFgJMhOKKbpliCMIaq0SkhXY0KBSXWfdQU38AuKQ8FdOQXuO944VzfXiBt6xwODZ1HDpSp8U22rVq-mL52ayXGcCVjdeg/s1600/IMG_20141227_243419368.jpg" width="360" /></a></div>
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Here is the final hexapod assembly. I ended up milling three plates from polycarbonate to create the electronics mount. The electronics are all held in with zip ties. I would have used screws, but I didn't want to make the standoffs required to mount the electronics with screws.<br />
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Unfortunately during testing I managed to break three servos. Shipping the hexapod back from break caused another four servos to die. All of the servos broke at the same internal gear. I haven't been able to finalize testing my leg motion code without a fully functioning set of legs . I chose not to use an existing set of code for the legs because I was excited to create my own algorithm from scratch. I need to rethink my servo choice and look into getting slightly more robust servos. Currently I am looking at using metal gear servos that are around five dollars each. I'm sure the hexapod will be up and running quickly once the new servos are integrated into the design.<br />
<br />JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-66561879420414231032014-11-30T22:03:00.000-08:002015-01-30T19:06:36.111-08:00Servo Spline Adapters<div class="separator" style="clear: both; text-align: left;">
My transmission design for the Mini Combat Robot uses large servo gears. Unfortunately the output from these gears is a spline shaft. I had to come up with a way to easily adapt to the spline without making a sketchy connection with the servo horns that are meant for those servo gears. My first technique for making a servo spline can be done with a milling machine. It's a fairly straight forward and doesn't require special tools.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3v8myeyAu9IP_nlotavxGQ-z2So2lnD-N4QTgwW9RhQyPIS5lVEJKE__nA6vRESpaW7ueHWKppphSAjs_pwyZKlKTInZnJTVdwtKK1CbkDyP_a2cFMyuIQtceabpEwWEF4pZZIQfsg2Y/s1600/IMG_20140323_241129_573.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3v8myeyAu9IP_nlotavxGQ-z2So2lnD-N4QTgwW9RhQyPIS5lVEJKE__nA6vRESpaW7ueHWKppphSAjs_pwyZKlKTInZnJTVdwtKK1CbkDyP_a2cFMyuIQtceabpEwWEF4pZZIQfsg2Y/s1600/IMG_20140323_241129_573.jpg" height="320" width="240" /></a></div>
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I put a "blank" shaft into a collet block. The collet block isn't required, however holding a round part vertically in a vise can be difficult to align. It also has a good chance of slipping which could break tools and ruin the part. The first thing I did was drill a set of starter holes. I used a small carbide ball end mill because it was the only tool that could make a mark smaller than the drill bit I wanted to use. Each hole corresponds to one of the teeth in the spline. I designed the holes so the outer edge would meet up with the tip of each spline tooth.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhE-owlixiBg3IcF2cWB0mQwEQN5VBFh-W-yVsfvDnchEjwsxMUrR7j0U1DKf8vCTwdnpiYB9hcyrdHndCPXQrahMkAhpX5DqzJNnOLST06-Jz9pOLdV576_w3q-EVgD0e1Jy7Rgq0_Y4s/s1600/IMG_20140323_242133_353.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhE-owlixiBg3IcF2cWB0mQwEQN5VBFh-W-yVsfvDnchEjwsxMUrR7j0U1DKf8vCTwdnpiYB9hcyrdHndCPXQrahMkAhpX5DqzJNnOLST06-Jz9pOLdV576_w3q-EVgD0e1Jy7Rgq0_Y4s/s1600/IMG_20140323_242133_353.jpg" height="320" width="240" /></a></div>
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Once I made all of the starter dents, I proceeded to use the final size drill bit. Each hole was very close, but none of the holes intersected. If the holes intersect the drill bit will likely drift and break. The final step was to mill out the center. Milling out the center creates the inner part of the spline. It is important to design the geometry such that the leftover wall between the drilled holes fits between the spline teeth. I simply plunged and endmill down to the desired depth and let it swirl around to the correct diameter. This opened all of the holes drilled to the center.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiaeFD2UnWt8b6lZFRmuyBpgp8_DUFbUqMcbG0siW-2TZlIo0nJS5ClEZyMYJ4RIGInMYf05G3kyMchDKwcAq21rETf8F00SgG5oSQDhfJHWdsXoiS4BLWZ6DJ2kW3lSOMAHFnfUqkdFlg/s1600/IMG_20150129_185801876.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiaeFD2UnWt8b6lZFRmuyBpgp8_DUFbUqMcbG0siW-2TZlIo0nJS5ClEZyMYJ4RIGInMYf05G3kyMchDKwcAq21rETf8F00SgG5oSQDhfJHWdsXoiS4BLWZ6DJ2kW3lSOMAHFnfUqkdFlg/s1600/IMG_20150129_185801876.jpg" height="180" width="320" /></a></div>
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This is the final shaft. The part fit snugly on the spline and didn't seem to damage the spline even under loading conditions. I used this part on the Mini Combat Robot until a design iteration forced me to a 3D printed design (I no longer had access to a mill). Any mill with CNC or even a digital readout can produce splined holes.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkTA8c00illWioTfqsLEs35aw2rs97b8aDn0PUA20Z8i2DxdDxKHEGGXV1PTl84Xn5s8QBGzuR2_-2ePHrVX7vnjjxfAxTsO036IapAczZECfXjwNRYBcQUmwnTOZdqo8T4XphGoUj_Ys/s1600/IMG_20141125_231049_993.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkTA8c00illWioTfqsLEs35aw2rs97b8aDn0PUA20Z8i2DxdDxKHEGGXV1PTl84Xn5s8QBGzuR2_-2ePHrVX7vnjjxfAxTsO036IapAczZECfXjwNRYBcQUmwnTOZdqo8T4XphGoUj_Ys/s1600/IMG_20141125_231049_993.jpg" height="240" width="320" /></a></div>
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This is a 3D Printed replacement for the metal adapter. I needed a different pulley, but I couldn't use the metal spline shaft for the upgraded design. I decided to 3D print an adapter instead. I used the same geometry as the metal spline and simply printed a new adapter. It also slipped right on and worked first try.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyDohyphenhyphenAr7ESTfljtSAHtEDyQEVWKL_WEv5shQHH2hPui0tvAF-SnVv2wxh26VvtqGsKMjhQ85O5Nb9URwdPLsTwMMVTdfM3DJgh8Cmo-paHQ2kvp1frnraSTe6ladBePqYxmhpXghxI84/s1600/IMG_20150129_203340142_HDR.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyDohyphenhyphenAr7ESTfljtSAHtEDyQEVWKL_WEv5shQHH2hPui0tvAF-SnVv2wxh26VvtqGsKMjhQ85O5Nb9URwdPLsTwMMVTdfM3DJgh8Cmo-paHQ2kvp1frnraSTe6ladBePqYxmhpXghxI84/s1600/IMG_20150129_203340142_HDR.jpg" height="180" width="320" /></a></div>
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Here is the 3D printed servo adapter as well as a splined shaft that copied the original servo spline. I doubt an FDM type 3D printer could produce the details required for this spline to work, so I'm glad I went with the SLA type 3D printer (Form1+). Making giant servo splines led me to test miniature servo splines.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3iCBkQ0eiUnX8zdKc64bSorv2DLSbZQwKRYC01Beko03yobjzrqJLSf1jgLo8e_qmBnwcHX2R0P2L0-7uCteacLxFfrtl9YEC7n0W82nfy5nSJqwyqh3OdrNTC2aoK2P0vN9OUYid8o4/s1600/IMG_20141114_240041_057.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3iCBkQ0eiUnX8zdKc64bSorv2DLSbZQwKRYC01Beko03yobjzrqJLSf1jgLo8e_qmBnwcHX2R0P2L0-7uCteacLxFfrtl9YEC7n0W82nfy5nSJqwyqh3OdrNTC2aoK2P0vN9OUYid8o4/s1600/IMG_20141114_240041_057.jpg" height="240" width="320" /></a></div>
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The first part to my process to make a servo spline is getting a picture of the spline itself. I use this picture and one reference dimension (the outside diameter of the spline) to trace the spline profile. This seems to be pretty reliable and is able to get details that my calipers can't measure.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtcVx4wXgmKCgzTApmNtv9CFHGWXKz0qpzl0-H5Dyc2ZcpmowWyjxR6EOudIXn2-TrZZPtGwxGDDlCMgoVwjB7wrF-MKmoMKXaXZljxLaDZG5F0YeAU31V47GP0QkNSrx43CNbnr0wffQ/s1600/Servo+Spline+CAD.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtcVx4wXgmKCgzTApmNtv9CFHGWXKz0qpzl0-H5Dyc2ZcpmowWyjxR6EOudIXn2-TrZZPtGwxGDDlCMgoVwjB7wrF-MKmoMKXaXZljxLaDZG5F0YeAU31V47GP0QkNSrx43CNbnr0wffQ/s1600/Servo+Spline+CAD.JPG" height="200" width="320" /></a></div>
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Here is a screen shot from the CAD I used for the servo spline. I get the spline dimensions by tracing the profile that comes from the drawing. It is surprisingly fast to CAD this way. The camera image reveals a lot of details that my measuring instruments won't capture.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIK3JFJRhVmEEb59E99L2EUatfqmzuXwabapCA1dCZYL0CK1TmqK8Cd-mGI24j1wSo8pYoOLtNWuJYTGeHlythbh0LUEtjW2cOgukYURslO7gdj5ILKiDSWGD64-98q7dAh-XLlb4fpm8/s1600/IMG_20150129_202609920.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIK3JFJRhVmEEb59E99L2EUatfqmzuXwabapCA1dCZYL0CK1TmqK8Cd-mGI24j1wSo8pYoOLtNWuJYTGeHlythbh0LUEtjW2cOgukYURslO7gdj5ILKiDSWGD64-98q7dAh-XLlb4fpm8/s1600/IMG_20150129_202609920.jpg" height="180" width="320" /></a></div>
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Here is a servo spline made for a micro size servo (9g servo). The printer was able to handle the small details required to make the spline.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHlsglbWw4FV80-girFsv6gQKB0eosAgm5wX3cBXUHg_8k54me_YnE-gs18Srhdw4s_kA2UuLu1LTvrTaffp0gGuvwwtKvbZ8B2N59l6bNLpklfPsIttSbSZ0dODSSwXMbBHSpUBWQj2Y/s1600/IMG_20150129_202848071.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHlsglbWw4FV80-girFsv6gQKB0eosAgm5wX3cBXUHg_8k54me_YnE-gs18Srhdw4s_kA2UuLu1LTvrTaffp0gGuvwwtKvbZ8B2N59l6bNLpklfPsIttSbSZ0dODSSwXMbBHSpUBWQj2Y/s1600/IMG_20150129_202848071.jpg" height="180" width="320" /></a></div>
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The gear fit perfectly onto the servo first try. I attempted to strip the spline, however I only managed to cut myself with the 3D printed gear teeth. I was unable to get the spline to skip on the servo.</div>
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For future projects using large servos I will attempt to make more metal shafts and splines. I find them more durable than the 3D printed parts. I also know the servo gears will strip before the metal spline slips. The 3D printed splines for smaller servos are too awesome. I'm still amazed the printer can handle details like that. The cool part is these splines can be put into any 3D printed part. It doesn't matter whether the part is round, square, or even a hexapod leg!</div>
JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com11tag:blogger.com,1999:blog-4585776524802028435.post-22791237468860607502014-11-29T18:19:00.000-08:002015-01-30T18:59:52.014-08:00Mini Combat Robot Update... againI decided to use my new 3D printer to solve any engineering problems with the mini combat robot. The first problem was making the motor controllers fit in the space I left for them.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-VowfxF2B1BDx6dpNmrU_xGFaKqFt3uUdGyRG74dK3_Z06pF5llYs7OLVsVfrO8npTpSory5o0GlwNeyMxQoinv9iZcGyZCVIXR5kewanBFIi1kVvcSPyBSDeeNlq0DVLrp1RDmZ5XYs/s1600/IMG_20141111_204351_845.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-VowfxF2B1BDx6dpNmrU_xGFaKqFt3uUdGyRG74dK3_Z06pF5llYs7OLVsVfrO8npTpSory5o0GlwNeyMxQoinv9iZcGyZCVIXR5kewanBFIi1kVvcSPyBSDeeNlq0DVLrp1RDmZ5XYs/s1600/IMG_20141111_204351_845.jpg" height="240" width="320" /></a></div>
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Here is the motor controller mount as it came from the 3D printer. The part wasted a lot of material in the supports. I designed the part to fit the motor controllers perfectly into the robot frame. This part might be machinable, but I would avoid making this part if I didn't have a 3D printer.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_dc_gztNpkmTeoEDuelbDP79vJdHeyYMoiWhjaoea3iAYNY8SAKKuP-C3U6o10pNWj1D_1CWaSzS3gnlGaWRakDM2xaxdpgPj88aheCrunZC0jfoukYFCRLmwGcRIeEvOH16rxoBJQW0/s1600/IMG_20141112_012629_366.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_dc_gztNpkmTeoEDuelbDP79vJdHeyYMoiWhjaoea3iAYNY8SAKKuP-C3U6o10pNWj1D_1CWaSzS3gnlGaWRakDM2xaxdpgPj88aheCrunZC0jfoukYFCRLmwGcRIeEvOH16rxoBJQW0/s1600/IMG_20141112_012629_366.jpg" height="240" width="320" /></a></div>
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The new motor controller mount allows me to fit the wires in to the available space. It may look messy, but I'm just happy I could make the motor controllers fit into the frame. I knew the motor controllers would fit into the frame, but I didn't account for the wires or connectors. These left the space a bit too cramped to properly mount any of the components. The new 3D printed mount allows me to securely mount the controllers without risking damage during combat matches.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiaqMF1EGZ_fkQ6sOa-kSqYm8udacFue8LZv-_1EiBTlSGziojWrPcm20S1Vl3BY5EERB_DZDK0XMIUbVcW1Qzih7jkRVZXRtCYIdwUOaBHyEWGEJLANkl9cCcH-82w9-vRQrvgCscfJY/s1600/IMG_20141125_231008_094.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiaqMF1EGZ_fkQ6sOa-kSqYm8udacFue8LZv-_1EiBTlSGziojWrPcm20S1Vl3BY5EERB_DZDK0XMIUbVcW1Qzih7jkRVZXRtCYIdwUOaBHyEWGEJLANkl9cCcH-82w9-vRQrvgCscfJY/s1600/IMG_20141125_231008_094.jpg" height="240" width="320" /></a></div>
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The robot looks pretty slick. I was able to replace the old 3D printed parts either with properly machined components or parts printed with my new 3D printer.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikLb8HHKKDutiPwmTIZxkVIbjT4OId-THcANoIBLu3H2PJtEm-wB-9dpdD128wNUGXhV0vbeqH6BCvFxx0gJkLWDf4BAwY3T4j2cSPlrsdCjCdJVfj4INPWI_VNwTyPcHFG5Rbqp3IIeg/s1600/IMG_20141125_231039_624.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikLb8HHKKDutiPwmTIZxkVIbjT4OId-THcANoIBLu3H2PJtEm-wB-9dpdD128wNUGXhV0vbeqH6BCvFxx0gJkLWDf4BAwY3T4j2cSPlrsdCjCdJVfj4INPWI_VNwTyPcHFG5Rbqp3IIeg/s1600/IMG_20141125_231039_624.jpg" height="240" width="320" /></a></div>
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This underside view of the robot shows how the motor controller fits into the robot. I still need to replace the top and bottom plates with real armor instead of thin acryllic.</div>
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I didn''t quite mange to finish the robot before losing machine shop access. I've been able to replace most of the poorly 3D printed parts with either higher quality plastic components or metal components, however there is still a fair amount left to finish the robot. The biggest thing the robot needs is a spinner.</div>
<br />JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-24421468325330935252014-11-01T21:21:00.000-07:002015-01-30T18:56:27.287-08:00Quick Project - Evil IronMan<div class="separator" style="clear: both; text-align: left;">
I got invited to a Halloween party about two hours before the party started. The party had a mandatory costume policy. Being an engineer and a new owner of a 3D printer I figured I HAD to 3D print my costume. The first thing that came to mind when thinking of 3D printing and Halloween costumes was an arc reactor. I've seen a bunch made on the internet and even a few for various Halloweens in the past. I remember that I had a box of LEDs. Unfortunately, I discovered that I only had two blue LEDs. Luckily I also had eight red LEDs... so the obvious costume became evil IronMan. I spent about 30 minutes drawing up the part in SolidWorks and then sent it to the printer. The print time was a little under two hours (it's cool to be slightly late to parties). While the part was printing I had to make the wiring.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmPjAM2Pm3YqLFcPKfTVwZ_iOJjURpWcg-YbeX1kbkHFPKcrVJWppvQWRChyphenhyphenaNPYUy_yQIhKkqXxVkMhrlEEl2KxTCe2TwvwPxakV-Sf2vhu-1-I_fG0Hw3CTTqtwYITDd-fgjB3IwwTc/s1600/IMG_20141031_205636_249+edit.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmPjAM2Pm3YqLFcPKfTVwZ_iOJjURpWcg-YbeX1kbkHFPKcrVJWppvQWRChyphenhyphenaNPYUy_yQIhKkqXxVkMhrlEEl2KxTCe2TwvwPxakV-Sf2vhu-1-I_fG0Hw3CTTqtwYITDd-fgjB3IwwTc/s1600/IMG_20141031_205636_249+edit.jpg" height="172" width="320" /></a></div>
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I pushed each of the LEDs through a 1:1 drawing of the frame. I soldered all of the LEDs together with some solid wire to give some structure to the electronics. I also used two bent spiral wires for the + and - connections to the battery. I tore away the paper to release the electronics for the final assembly. I didn't use any current limiting resistors or a proper current driver because the battery voltage was lower than the rated voltage for the LEDs. I also figured that the small coin cell battery wouldn't be able to supply enough current to fry six LEDs in parallel.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizLc3VWQkJZqc_iMQLkxdLGuasWYOKI9jgtZBsaLCJ0FoirPiDJC7uyxo9MDxG9bApL7iMfomWUjqbu7m7zxH0SLP6ZlEH3_avbfdj-SD2fvqth4l1wookjXMEmnv3vppcFnd65t9ubIg/s1600/IMG_20141125_232405_295.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizLc3VWQkJZqc_iMQLkxdLGuasWYOKI9jgtZBsaLCJ0FoirPiDJC7uyxo9MDxG9bApL7iMfomWUjqbu7m7zxH0SLP6ZlEH3_avbfdj-SD2fvqth4l1wookjXMEmnv3vppcFnd65t9ubIg/s1600/IMG_20141125_232405_295.jpg" height="240" width="320" /></a></div>
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Here's a top side view of the arc reactor. Each of the LEDs stuck out from the frame to ensure maximum brightness. It also saved some material and print time.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiPZG86jaV3KVJb8jmI4BwQwUaYP7-CXHWNbNRy4J6LcgQTBagoBl-8hRoeV0WBJzEzM_MFElm-DFapHc6D6d8TpVTagUezgLR81XcNGNAkA1VquP3pM56KaJcFXL2CK1KyDaQ4_mviR4/s1600/IMG_20141125_232414_375.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiPZG86jaV3KVJb8jmI4BwQwUaYP7-CXHWNbNRy4J6LcgQTBagoBl-8hRoeV0WBJzEzM_MFElm-DFapHc6D6d8TpVTagUezgLR81XcNGNAkA1VquP3pM56KaJcFXL2CK1KyDaQ4_mviR4/s1600/IMG_20141125_232414_375.jpg" height="240" width="320" /></a></div>
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This is the back side of the arc reactor. I have paper shoved between the battery and the contact to prevent the LEDs from turning on. I didn't have a switch so the back has to be unscrewed to connect and disconnect the battery.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVqSFXKrd5tJ3jO27LrZQsgTlrsOxMxq7PErXLzt3SX2Vs29K2b21kdRocgs_K3v9BYH2dxQ5nnpBm1U5YxvI1GTjTRCI43oL53JCX1rGHJtCy4nJl3sOrLE9QWdzYHwUhn2W-qKPh6LU/s1600/IMG_20141031_214836_216.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVqSFXKrd5tJ3jO27LrZQsgTlrsOxMxq7PErXLzt3SX2Vs29K2b21kdRocgs_K3v9BYH2dxQ5nnpBm1U5YxvI1GTjTRCI43oL53JCX1rGHJtCy4nJl3sOrLE9QWdzYHwUhn2W-qKPh6LU/s1600/IMG_20141031_214836_216.jpg" height="320" width="180" /></a></div>
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This is the arc reactor shining through my shirt. The camera doesn't do a very good job showing how bright the LEDs looked shining through my shirt. I used lots of tape to hold it in place.<br />
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Surprisingly the arc reactor stayed lit up all night. I didn't even have to break out the spare battery and hex key that I kept in my pocket. The design wasn't too great, but im pretty proud of it considering it went from concept to finished product in a little over two hours!JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-91123133898274295962014-10-25T18:58:00.000-07:002015-01-30T18:52:51.168-08:00New Machine - Form1+ 3D Printer<div class="separator" style="clear: both; text-align: left;">
After thinking it over for a few months I decided the usual FDM type 3D printer I was building (the kind that squirts out plastic like a hot glue gun) wasn't going to meet my needs. I just moved and no longer have access to mills, lathes, or other metal working equipment aside from my trusty file and hand drill. I decided a 3D printer was the only way to continue my projects without making a mess in my apartment. After looking around at the different available 3D printers I came across the Formlabs Form1+ printer. This printer uses SLA technology. SLA printers use a photosensitive resin that solidifies when exposed to a light source. The resin in this printer cures with a UV laser.</div>
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I need a printer than can make parts with fine details, high accuracy, and decent strength. Although I'd love a printer that could make metal parts, however I'm a few orders of magnitude away from being able to afford one. I decided to settle with a printer that makes plastic parts. The FDM printers (like the one I am/was building) are nice because they have become very popular. The popularity has driven down the material costs which makes the printers very affordable. There is also a large number of users who have lots of great tips and tricks for getting high quality parts. Unfortunately the nozzle design in an FDM pritner limits the minimum features size. The fusion of layers through heat also tends to leave voids which causes very different properties depending on a part's orientation in the printer. This can make "engineering" grade parts difficult to make.</div>
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The SLA printers have only recently become available to hobbyists, so there is not a very large number of users. The material is somewhat proprietary, so it costs 3-5 times more than an FDM printer for a given volume of material. The quality from the SLA printers can't be beat by the FDM printers. The laser curing technique is able to make much finer details in the parts. I expect to be printing gears that are 32 and maybe even 64 pitch. The parts are also solid, so the material properties are going to be the same regardless of the part orientation. There should also be fewer voids in the parts, which will make "engineering" grade parts easier to produce.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXY3_bCoTaG-J0oOa8c1n6HTQkKnctzmx44aRGE6VhKrvUyCb5dSNx23Dfl5TBT_I_HLTcgjySfzXr_JI2BErZYzDmmpcYd8kirFVoFnGQT0Vs4ijf3A6qt5JCy_l1udtdEuJNxuT7B5o/s1600/2014-10-21+20.25.24.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgXY3_bCoTaG-J0oOa8c1n6HTQkKnctzmx44aRGE6VhKrvUyCb5dSNx23Dfl5TBT_I_HLTcgjySfzXr_JI2BErZYzDmmpcYd8kirFVoFnGQT0Vs4ijf3A6qt5JCy_l1udtdEuJNxuT7B5o/s1600/2014-10-21+20.25.24.jpg" height="640" width="360" /></a></div>
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Here's the printer in all its glory. I personally find the printer aesthetically pleasing. It also fits well on my bookshelf.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSYh8SLd0C_0IgFgzcVHjcdDfc5fS6utkbYQ5mAlEizu1L1Hw89IxtOHQmx7fsxe7F0JXs9aUSRWzECF8nMvj0mWjO0kbD-n6-nvOTTcoNvueBjjqJ0Lf5tyJVf0rc66FuuUFi8d4xbss/s1600/2014-10-21+20.43.35.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSYh8SLd0C_0IgFgzcVHjcdDfc5fS6utkbYQ5mAlEizu1L1Hw89IxtOHQmx7fsxe7F0JXs9aUSRWzECF8nMvj0mWjO0kbD-n6-nvOTTcoNvueBjjqJ0Lf5tyJVf0rc66FuuUFi8d4xbss/s1600/2014-10-21+20.43.35.jpg" height="180" width="320" /></a></div>
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Here's the setup for my first prints. These parts are shock spring mount replacements for my rc car. The original ones no longer fit properly due to my machined replacement parts not being the exact same geometry as the original components.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKbzy9eHEfRLpbqBXC9VSopKIDxB9gbV2Ife9xxhSTJ9nJtco_l33tXbtAG2HtsCIHi0uMT6KC_xaX-hGp7SN1swSqlkH4y8fYjK2b4GIjcYoq3Dv8X2EwSMxOFOtXphgKEQvRPMDlA2M/s1600/2014-10-21+20.45.32.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKbzy9eHEfRLpbqBXC9VSopKIDxB9gbV2Ife9xxhSTJ9nJtco_l33tXbtAG2HtsCIHi0uMT6KC_xaX-hGp7SN1swSqlkH4y8fYjK2b4GIjcYoq3Dv8X2EwSMxOFOtXphgKEQvRPMDlA2M/s1600/2014-10-21+20.45.32.jpg" height="180" width="320" /></a></div>
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The printer readout is pretty cool. It tells me the remaining print time and the number of completed layers. The remaining time is exact and can help me schedule my time around the printer so I can be as productive as possible.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVnkoS3z5_lqZBhCOwsASjhC0mpTs1hZc18nRnUhQbH4soZT-_BiOMnDVVayUiKlYIcwl13jUzxTQBwLYSVHcPY_uKHlW8kUqbTWW5ODLCFSdgy0ijda6_c1hehQ7d3adjAhoO_ZGXZoc/s1600/2014-10-21+21.29.23.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVnkoS3z5_lqZBhCOwsASjhC0mpTs1hZc18nRnUhQbH4soZT-_BiOMnDVVayUiKlYIcwl13jUzxTQBwLYSVHcPY_uKHlW8kUqbTWW5ODLCFSdgy0ijda6_c1hehQ7d3adjAhoO_ZGXZoc/s1600/2014-10-21+21.29.23.jpg" height="180" width="320" /></a></div>
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This printer is upside down compared to FDM printers. The table rises out of the resin to grow the parts. It's a pretty neat concept and seems to work well.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrLbhqFJse-hQXdvyWDFLFF06LPQ8qzxaNUjTm5ffKoGa0TfI0s8Et2uS8oM1usm5bGGln1WroAq7n0KZYaD4SS_zhe_uq5GTKB2zEZcL3rUV_tKM9nod59XHnm9o_QOOfibCKT1Xxfro/s1600/2014-10-21+22.01.06.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrLbhqFJse-hQXdvyWDFLFF06LPQ8qzxaNUjTm5ffKoGa0TfI0s8Et2uS8oM1usm5bGGln1WroAq7n0KZYaD4SS_zhe_uq5GTKB2zEZcL3rUV_tKM9nod59XHnm9o_QOOfibCKT1Xxfro/s1600/2014-10-21+22.01.06.jpg" height="320" width="180" /></a></div>
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Here are the final parts after removing the excess resin with isopropyl alcohol. They came out perfectly first try. I'm sure more complicated parts or parts with tighter tolerances will require some test parts, but parts like these take nearly zero effort to make.<br />
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Overall I'm pretty happy with the printer. I have more project ideas than ever now that I can make parts without labor. I'll be running test parts for things like gears and press-fits. For now I'm not going to finish the 3D printer I started making. The FDM printers can't make the parts I want to make. It is a good XYZ CNC platform, so I should be able to use it for another project some time in the future.JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-80218077733217013332014-07-20T19:22:00.000-07:002015-01-30T18:41:23.919-08:00New Project - RC Car<div class="separator" style="clear: both; text-align: left;">
I've wanted a real RC car (not one of those tiny indoor only RC cars) since I was a little kid. Now that I'm a big kid I can just go out and get one. In this case I mail ordered a relatively cheap 4WD 1:10 scale buggy. The frame came as a kit. I had to pick out the motor, motor controller, radio, and batteries. I already had the radio from the mini combat robot, which cut the cost of the car. The reason I decided to buy a RC car instead of building one was that I didn't want to build something and then decide it was boring. I figured a cheap RC car would require repairs and could have an opportunity for many custom parts.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgw6DfHR_5uNMiN5V3oaOZQQH7QXWvrfPS2dpggIkrh9DVk_STF6l34XIjLFnRoqgcErqZKGuxYq-ToTosxj8h8Rjkwe3q9vIIKcxGFO7F-gDBoZKlNpvRFOnFwSPmN7JHUsvb5-bRIH6M/s1600/Action+Shot.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgw6DfHR_5uNMiN5V3oaOZQQH7QXWvrfPS2dpggIkrh9DVk_STF6l34XIjLFnRoqgcErqZKGuxYq-ToTosxj8h8Rjkwe3q9vIIKcxGFO7F-gDBoZKlNpvRFOnFwSPmN7JHUsvb5-bRIH6M/s1600/Action+Shot.jpg" height="253" width="400" /></a></div>
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Here's a sweet action shot of the car before parts started breaking. I put a "somewhat" larger motor and battery in the car than suggested. The car's peak speed is over 40mph! (timed by driving on a football field) It probably has more power than I can control... I flipped it and hit things a full speed many times as well as taking jumps that brought the car around head height in the air. Needless to say the cheap plastic parts started breaking real fast.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHEGaAYzFXVsHMAeRR-2gLd6tmOwU8kdTZbyJ8VPj9DNk6NUYZ9joM0tISO2QVmmv0NhxEwwWdWPgcARvwTWxvGUiCS5QrGj8tK653exL2yY3AAoSZvGpvg6u_V5AJC0U9J6TNktkVE58/s1600/IMG_20140627_121745_965.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHEGaAYzFXVsHMAeRR-2gLd6tmOwU8kdTZbyJ8VPj9DNk6NUYZ9joM0tISO2QVmmv0NhxEwwWdWPgcARvwTWxvGUiCS5QrGj8tK653exL2yY3AAoSZvGpvg6u_V5AJC0U9J6TNktkVE58/s1600/IMG_20140627_121745_965.jpg" height="240" width="320" /></a></div>
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Here's the machining of a new shock absorber mount. The original part didn't break, but it bent ~45 degrees. I decided a metal version would be a good first upgrade for the car.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYD4uypFA1lRK5gUlIINfy-S1aDqYj_fqaQQCVD9pTqrmvaOTf7Yjl9_7L3ASGvlFpHvDOPimt0PYUxZclUG9hEpNqLrgXzEIYZ6XK92SMtLNA3YnfmyQxvTcgRs0arFzJ3HCT-XKxkE4/s1600/IMG_20140627_135415_343.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYD4uypFA1lRK5gUlIINfy-S1aDqYj_fqaQQCVD9pTqrmvaOTf7Yjl9_7L3ASGvlFpHvDOPimt0PYUxZclUG9hEpNqLrgXzEIYZ6XK92SMtLNA3YnfmyQxvTcgRs0arFzJ3HCT-XKxkE4/s1600/IMG_20140627_135415_343.jpg" height="320" width="240" /></a></div>
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Here is the aluminum part next to the original (which I bent back). I removed some of the extra "adjustment" holes that were in the original part. I also remade the pockets to make the part considerably stronger. I don't expect this part to break before any of the other parts on the car.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixA6sQwfwv5lHhUU3CWx5sEf2n6rmJ8JHjCE9AWUXLiAO2sg-Y5dWAXZuYf0SpLatmorg4rEfOgB2dm8rumO8o-uBjQMLyoFTjq2P9PD2NOt5IND8OjT9wQVviUARHmciAPFJwQpV6hhY/s1600/IMG_20140714_162224_794.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixA6sQwfwv5lHhUU3CWx5sEf2n6rmJ8JHjCE9AWUXLiAO2sg-Y5dWAXZuYf0SpLatmorg4rEfOgB2dm8rumO8o-uBjQMLyoFTjq2P9PD2NOt5IND8OjT9wQVviUARHmciAPFJwQpV6hhY/s1600/IMG_20140714_162224_794.jpg" height="240" width="320" /></a></div>
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After a few more jumps I busted the front A-arms. I didn't have a spare axle so I was forced to bend this one straight again. Thankfully the axle was made from cheap steel and I have decent pliers.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWCNbOExIvtM9F8YlkSmYOz48X2-BenrkPcHhGAHtk1-KOoS7ZNW2QYmbVtuLyl4dn8DrNeNfuPBfYoVKCcHfnX3rgD4MQ6XDvlWYEblKpNrmUqACW3WkeLdlxvv1TL2NuLQyCHOYbYyg/s1600/IMG_20140714_162301_617.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWCNbOExIvtM9F8YlkSmYOz48X2-BenrkPcHhGAHtk1-KOoS7ZNW2QYmbVtuLyl4dn8DrNeNfuPBfYoVKCcHfnX3rgD4MQ6XDvlWYEblKpNrmUqACW3WkeLdlxvv1TL2NuLQyCHOYbYyg/s1600/IMG_20140714_162301_617.jpg" height="240" width="320" /></a></div>
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Here is the A-arm that broke. The plastic split at the axle. This part is not a simple 2D part like the shock mount.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-z_I-zrTr9xOrwo7IoVzkzRNoVsDNbV-5IBDhjjJoEX7lYkLXR9l-r-ISJQstiW1_t84UeumhSnbdyJPVP6foepjzPX2bkg__SJLp4_UdBA9ygwkRABeQUFSMQta56jPT3QQDLR0I7hE/s1600/IMG_20140716_163634_042.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-z_I-zrTr9xOrwo7IoVzkzRNoVsDNbV-5IBDhjjJoEX7lYkLXR9l-r-ISJQstiW1_t84UeumhSnbdyJPVP6foepjzPX2bkg__SJLp4_UdBA9ygwkRABeQUFSMQta56jPT3QQDLR0I7hE/s1600/IMG_20140716_163634_042.jpg" height="240" width="320" /></a></div>
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I started the part from flat aluminum plate. I forgot how slow it is to mill with a 1/8" endmill...<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpK0IcvJTlgxFXxpHjCOZ1H4Dc2IsIiVfYQlGysioRpbGmeA1zt__v5BJvKyX8CEEQJdL8oCfau6F6C6oXFu7CkyEDadrzFf7vUb8t79zIY8AaM7uTm8MObjTRj3b46Eazbo8ym6w78RY/s1600/IMG_20140716_215139_465.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpK0IcvJTlgxFXxpHjCOZ1H4Dc2IsIiVfYQlGysioRpbGmeA1zt__v5BJvKyX8CEEQJdL8oCfau6F6C6oXFu7CkyEDadrzFf7vUb8t79zIY8AaM7uTm8MObjTRj3b46Eazbo8ym6w78RY/s1600/IMG_20140716_215139_465.jpg" height="240" width="320" /></a></div>
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I wanted to save material so I did a REALLY good job orienting the stock on the mill table.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiQVvkb6XVMui7y2Vg_9i3hKm1mXONVLRaz2LmQpBu1gd0VF_tc4vOoOqnOJ1TbtVr61PKkFYgLTY_dkGp5WYTKkMBYJACIDeqMYoZLe-OXxtf5cnUwQHcjEC9y7nExkOW-n_HfK7YCVU/s1600/IMG_20140717_212306_313.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiQVvkb6XVMui7y2Vg_9i3hKm1mXONVLRaz2LmQpBu1gd0VF_tc4vOoOqnOJ1TbtVr61PKkFYgLTY_dkGp5WYTKkMBYJACIDeqMYoZLe-OXxtf5cnUwQHcjEC9y7nExkOW-n_HfK7YCVU/s1600/IMG_20140717_212306_313.jpg" height="240" width="320" /></a></div>
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Here's a before and after picture of the side machining. The parts required a total of 3 sides of machining each.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiWykMy0JDMQCoFGY8IatSYhuGuNShvw2uq47BnUYN6y1fmXhH2UX_uH2cjWyLTrp8hiYE74Lxz2UzKkRmHTtrbbpqY8wWemDe9i-SXFGqvq8182g99uk3OKfbFPEJjmmSVUG8wk6SBC0/s1600/IMG_20140717_220141_510.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiWykMy0JDMQCoFGY8IatSYhuGuNShvw2uq47BnUYN6y1fmXhH2UX_uH2cjWyLTrp8hiYE74Lxz2UzKkRmHTtrbbpqY8wWemDe9i-SXFGqvq8182g99uk3OKfbFPEJjmmSVUG8wk6SBC0/s1600/IMG_20140717_220141_510.jpg" height="240" width="320" /></a></div>
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My trusty mini-vise did a great job holding the parts. I also tried a set of carbide drill bits. They seemed to drill much better than my sketchy old drill bit set.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh28Jcp3QguWKwExTow2pidj3kKAigq6opl8afznWjp0B21HVpJmSTSa5d8I1nDHzoQlT440dfXOYgG6pn9xFJXHDIuRYyE2Qk49fgJmRT-q4_6pg9JkCig2RpNbwdgEPSHxO9kkDkESVU/s1600/IMG_20140719_182518_574.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh28Jcp3QguWKwExTow2pidj3kKAigq6opl8afznWjp0B21HVpJmSTSa5d8I1nDHzoQlT440dfXOYgG6pn9xFJXHDIuRYyE2Qk49fgJmRT-q4_6pg9JkCig2RpNbwdgEPSHxO9kkDkESVU/s1600/IMG_20140719_182518_574.jpg" height="240" width="320" /></a></div>
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The new A-arms look pretty nice on the car. The shock spring mounts rub the aluminum a bit. I'll need to make some replacements to prevent any possible damage to the shocks.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig7q_Xhu6LF2l5bhHz-QOCMgw2h40d0gtW6BkBAT_jN6FgzDtnDzfZ_hwjRipDd_xbbOZp03UzPwIRjSNww-qM9uC5H6cSfLKHFX8W0GcvNVgBeTCxtaR5DqhbNS27rWUDOXTYaA2J5yA/s1600/IMG_20140719_182538_737.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig7q_Xhu6LF2l5bhHz-QOCMgw2h40d0gtW6BkBAT_jN6FgzDtnDzfZ_hwjRipDd_xbbOZp03UzPwIRjSNww-qM9uC5H6cSfLKHFX8W0GcvNVgBeTCxtaR5DqhbNS27rWUDOXTYaA2J5yA/s1600/IMG_20140719_182538_737.jpg" height="320" width="240" /></a></div>
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Here's the whole car with its cover attached. The rear wheels are pretty worn down. Those will have to be replaced soon as well.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirR8bYxSJubwt-gdCK3NwYV6WRbw4yhqOcn1otZN2OAbFGhvDI3hVfqTQA9axWNfSlAc5OGCyqU9BJc0xX82GlXGTL2FNiGalvvMmuAiFOa2mShUgOZgSa7w2fPm5FvsZ1WZcNQBuScbI/s1600/IMG_20140719_182552_786.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirR8bYxSJubwt-gdCK3NwYV6WRbw4yhqOcn1otZN2OAbFGhvDI3hVfqTQA9axWNfSlAc5OGCyqU9BJc0xX82GlXGTL2FNiGalvvMmuAiFOa2mShUgOZgSa7w2fPm5FvsZ1WZcNQBuScbI/s1600/IMG_20140719_182552_786.jpg" height="320" width="240" /></a></div>
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Here's the car without the cover attached. The electronics are fairly compact. I've been very impressed with the motor and motor controller combination. Neither has melted yet!<br />
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Overall I'm glad I bought an RC car instead of making one from scratch. I really wouldn't be able to beat the price I paid for the frame. When a part breaks I can have fun making a replacement. Eventually the whole car will be custom!JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-20112333459481990372014-03-24T17:16:00.000-07:002015-01-30T18:34:34.227-08:00Mini Combat Robot Update<div class="separator" style="clear: both; text-align: left;">
I tend to prioritize class work rather than my own projects, so I haven't made too much progress on the Mini Combat Robot. Hopefully I'll find the time to finish this project before the semester is over and I lose access to the nice CNC machines at school. </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7f2amLmxhMreHSD1qhzW8szM7NulWnO5yt8LAuw1v8W2l7wQrXPJkQ4j83gQNEjmKxWQiNHvw1sTNio7b0azHVymZnBTu3jbnFrwYNUvhMiJKgFlHYsWIrgzyIihw1AZO_bCbN7SGfVE/s1600/IMG_20131216_224753_341.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7f2amLmxhMreHSD1qhzW8szM7NulWnO5yt8LAuw1v8W2l7wQrXPJkQ4j83gQNEjmKxWQiNHvw1sTNio7b0azHVymZnBTu3jbnFrwYNUvhMiJKgFlHYsWIrgzyIihw1AZO_bCbN7SGfVE/s1600/IMG_20131216_224753_341.jpg" height="240" width="320" /></a></div>
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The frame started to come together nicely. I quickly held the unfinished parts together with a few clamps just to see how the frame looked in person. I have quite a few 3D printed parts on the robot. These parts are low quality compared to nicely machined parts. I want to see the robot assembled as quickly as possible, so I decided to 3D print a number of non critical parts.. The 3D printed parts should hold up well enough to drive around , however almost all of them will need to be replaced before the robot goes into combat.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUh9NZCN3gWh9A6OGPjscLe22v-Bhk3bautUSMpBDU4pXK9X1AjyYye2_njr-UHUgnxbM4Kq5K-HYrBLKGwC0AdrXCxkt5nkaxfj2InR9lVk2dur9n1do71aleNbqNW9J1uBez88-Q2mc/s1600/IMG_20131216_224803_528.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUh9NZCN3gWh9A6OGPjscLe22v-Bhk3bautUSMpBDU4pXK9X1AjyYye2_njr-UHUgnxbM4Kq5K-HYrBLKGwC0AdrXCxkt5nkaxfj2InR9lVk2dur9n1do71aleNbqNW9J1uBez88-Q2mc/s1600/IMG_20131216_224803_528.jpg" height="240" width="320" /></a></div>
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The 3D printed transmission mounts might stay... They seem to be strong enough to handle the torque output from the transmission. They're also green which matches the motor's color.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmjbi9vLmWZdbyYKi2DbM1znldGF6iuhkwQPwnx5GtrONisV4GV5FZhM-vu16sf3tzwRWlLbzOt-_0T3HabRbwocfVxfAEnAUiAQw6exVtywwKnJJhaVFz-mlSC7P1GpCyd6095L_UsOQ/s1600/IMG_20131220_103740_846.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmjbi9vLmWZdbyYKi2DbM1znldGF6iuhkwQPwnx5GtrONisV4GV5FZhM-vu16sf3tzwRWlLbzOt-_0T3HabRbwocfVxfAEnAUiAQw6exVtywwKnJJhaVFz-mlSC7P1GpCyd6095L_UsOQ/s1600/IMG_20131220_103740_846.jpg" height="240" width="320" /></a></div>
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Here is right after I finished drilling and tapping all of the cross bars. this is the first time the robot has actually looked like the final product in the CAD. The robot uses "tank treads" which are made from timing belt. They took less space than wheels and seemed like a simpler, more reliable way to make the robot move.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0ivzkuBLkuCOLbzjH6Ani_1s9gijmNX6uCIr6GuxAcni5pYWMKCemkq0nuQWYfrfLD68q7S9lCYnbTnQ93djdOb_Mssb0VUbwx63Q2w3nw0YUJGtrZnR5kaj8l8AFu_-DTTNEsMou7nY/s1600/IMG_20140314_195505_986.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0ivzkuBLkuCOLbzjH6Ani_1s9gijmNX6uCIr6GuxAcni5pYWMKCemkq0nuQWYfrfLD68q7S9lCYnbTnQ93djdOb_Mssb0VUbwx63Q2w3nw0YUJGtrZnR5kaj8l8AFu_-DTTNEsMou7nY/s1600/IMG_20140314_195505_986.jpg" height="240" width="320" /></a></div>
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These are all of the frame parts. Although they aren't the simplest shapes, they can all be made with a standard milling vise setup. They took longer to machine than I had estimated, but I guess that is always the case with machining. Cutting the 45 degree angles took some patience, but they shoud be worth it if there are any other robots with spinners. Hopefully the beveled edges will help the robot deflect any kind of spinner weapon.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrxcNZrEJ3OhKQy6tq4d2Ap8iAeB93p_Qz9x0Kcb_Siaxh1BkeTQWGq2YL1e4hWXaukZDMFURlSkket1eAd8yXMlFLZWU7OcpOZwdklFgxCgpk8NbouEnUnpGcxyh8EQyuOKCi_5RNM3o/s1600/IMG_20140323_114218_623.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrxcNZrEJ3OhKQy6tq4d2Ap8iAeB93p_Qz9x0Kcb_Siaxh1BkeTQWGq2YL1e4hWXaukZDMFURlSkket1eAd8yXMlFLZWU7OcpOZwdklFgxCgpk8NbouEnUnpGcxyh8EQyuOKCi_5RNM3o/s1600/IMG_20140323_114218_623.jpg" height="240" width="320" /></a></div>
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This is the state of the robot for now. It is by no means ready for combat. It still needs a spinner, replacement parts for the currently 3D printed parts, electronics mounts, as well as top and bottom armor plates. I'll try to finish this project before the semester ends, but I can't make any promises...</div>
<br />JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-47895282740878673602013-12-14T17:29:00.002-08:002013-12-14T17:35:01.889-08:00New Project - 3D Printer<div>
I decided to make a 3D printer. 3D printing seems to be the wave of the future for producing many parts. There are a few different types of 3D printers, one of which, the extrusion type, seems to be the most popular on the market. This kind of 3D printer takes in filament, which is essentially plastic wire, and extrudes it into a small bead of plastic. The printer moves the extrusion nozzle on a table to draw a part. This printer is basically a fancy hot-glue gun that makes 3D shapes. </div>
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The consumer grade 3D printers on the market are pretty slow and they don't produce the best quality parts. In addition, most of them don't use support material. Support material is a second material used by the 3D printer with the standard plastic. The support material can be dissolved so you can make parts with overhangs or other features that require additional support.</div>
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The concept for this 3D printer is to use high power hobby brushless motors, similar in size and power to those used in the heavy weight combat robot I built last semester. These motors aren't meant to be used as servos, so the printer needs custom motor controllers as well as additional hardware to properly drive the motors.</div>
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The brushless motors have 3 wires: phases A, B, and C. Brushless motors have magnetic coils in multiples of 3, one set for each of the 3 phases. These coils are connected together in a few different configurations, such as wye or delta, which provide different characteristics to the motor. Driving the motor is the same regardless of the coil configuration. Phases A, B, and C must be pulled to supply voltage, ground, or floated to make the motor rotate. A nice resource for this would be AN857 from Microchip. Microchip makes microprocessors, transistors, and other components used in motor controllers. AN857 is one of their application notes on brushless motor control.</div>
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Most hobby brushless motors are sensorless, so there is nothing added to the motor to help a controller determine when to switch which phases are being powered. Since a servo needs an encoder, I decided to use this to perform the commutation, or timing for when the motor controller switches which coils are powered.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQPc1vbQIh63zVnKg6KDjivkFNG-SOGJ48HnhLbXZ14CuLQ_eGAwB32fFkyfrFe3W5exvR2cSD8yVCcO2WHRrt2gO3yr5BzG7ggheP96IzeR8Q_8s8iS8vKeGWW38iRfWee3ZcVBbvVjQ/s1600/IMG_20131212_142304_779.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQPc1vbQIh63zVnKg6KDjivkFNG-SOGJ48HnhLbXZ14CuLQ_eGAwB32fFkyfrFe3W5exvR2cSD8yVCcO2WHRrt2gO3yr5BzG7ggheP96IzeR8Q_8s8iS8vKeGWW38iRfWee3ZcVBbvVjQ/s320/IMG_20131212_142304_779.jpg" width="320" /></a></div>
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Here's a picture of the custom motor controller. This board uses power MOSFETs. MOSFETs are a type of transistor that is great for high frequency switching applications. There are 3 pairs of power MOSFETs; each pair corresponds to one of the motor's phases. One MOSFET in each pair is connected to the power line, and the other in each pair is connected to the ground line. If a high-side MOSFET is on, that phase will be connected to the power line. If a low-side MOSFET is on, that phase will be connected to ground. If neither is on, the phase will be disconnected from power and ground. If bot MOSFETs are on, power fill flow from the power line to ground. In this case the MOSFETs will form a short circuit. With a large power source, batteries or computer power supply, the MOSFETs will fry from too much current.</div>
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Portions of this project became a group effort for final projects in two of my electronics classes. The motor controller and its design are part of an advanced electronics course. The logic portion of the control, which is built on an FPGA and microprocessor board is part of a digital electronics and embedded systems course.</div>
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The logic portion of the motor controller is implemented on an FPGA. This includes PID control, which is being temporarily used until the mechanical portion is built; motor commutation; and coordinate input. An FPGA is a chip that has programmable logic gates. An FPGA allows the user to implement hardware design on the chip. Certain features like encoder counting, and motor commutation are very convenient to implement on an FPGA. Since these features are in hardware, certain situations can be made impossible. One example of this would be short circuiting two of the MOSFETs together.<br />
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<iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.blogger.com/video.g?token=AD6v5dx8q8U-Q0FWJARR9Z91yskD2hToDeWCTFBxcs48IbC-0pomqYUC9lcKIB1HmN5c5AJKefCmIPHe-OKnM2Z1' class='b-hbp-video b-uploaded' frameborder='0'></iframe></div>
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Here is a quick video of the motor. The motor controller is connected to a variable voltage supply. The motor controller is just switching which phases are powered depending on where the motor is positioned. The voltage determines the peak speed of the motor. I can't remember if this test went up to 12,000 rpm, but the motor and encoder functioned up to this rpm.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-ZMu2PCIdQrrNDh9ZeLzLMnWBdqzGHTINh18jPz9-EHrAGpYg2EQQL84ET3tOn-8ERd3my7TfYGYf2ky2LfzLp0wpdX9F-VVN6BaJnRdJIXtcMoiCQvU4RfNdKuLrzn3e90xly7BmSoQ/s1600/Quadrature+output.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="255" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-ZMu2PCIdQrrNDh9ZeLzLMnWBdqzGHTINh18jPz9-EHrAGpYg2EQQL84ET3tOn-8ERd3my7TfYGYf2ky2LfzLp0wpdX9F-VVN6BaJnRdJIXtcMoiCQvU4RfNdKuLrzn3e90xly7BmSoQ/s320/Quadrature+output.JPG" width="320" /></a></div>
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This shows the output of the encoder at 12,000 RPM. The signal is very clean. There are two square waves because this encoder is a quadrature encoder. There are two sensors, 90 degrees out of phase from each other, which read lines on the encoder. This lets the controller decode a resolution four times higher than the line count on the encoder. This encoder can be read at up to 8192 counts per rotation.</div>
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The mechanics for this project are meant to be relatively cheap to make. Linear slides in the gantry are built using hardened round rails and ball bearing bushings. These components are commonly used in other 3D printers and can be found very cheaply on sites like Ebay. The design for the printer isn't completely finished. There table motion system and mount, material mount, extruder, and heater block have yet to be designed. Thankfully the project proposed for class only required the motor controller, not the full 3D printer. I will likely finish these parts over the winter break when I have more free time.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAx4BKcIoFFRGkxdCmsBvpvsT-j5MHTz7WgTDbxAQYSJIfEFuhpk6sAuWWjFbqc4w4m1dtJoEPDOxEZiDuORmP7gRGtXhlx59xyYnjTlo4M7MA5XX_1fbsAldfrarrtwPxvMy9hSx4jF8/s1600/rrmini3dprinter.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="512" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAx4BKcIoFFRGkxdCmsBvpvsT-j5MHTz7WgTDbxAQYSJIfEFuhpk6sAuWWjFbqc4w4m1dtJoEPDOxEZiDuORmP7gRGtXhlx59xyYnjTlo4M7MA5XX_1fbsAldfrarrtwPxvMy9hSx4jF8/s640/rrmini3dprinter.JPG" width="640" /></a></div>
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Here's a screen shot of the CAD in the 3D printer's current state. The gantry design is done and looks pretty sweet. The table still needs some work, and the extruder doesn't exist.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUa51eg11rqAC-KtMjwpjw1R9qSiweqBpsaaRDd_Jo2MCkEIYyuytFNZloeewiTtmUmEhnf3y1oXhMRV8yyf2Q85GCxNln-UKpZ2fetkfRMOFq3Geh74_ttVILxnQGubUqZ27I1x52nAI/s1600/IMG_20131207_222105_678.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUa51eg11rqAC-KtMjwpjw1R9qSiweqBpsaaRDd_Jo2MCkEIYyuytFNZloeewiTtmUmEhnf3y1oXhMRV8yyf2Q85GCxNln-UKpZ2fetkfRMOFq3Geh74_ttVILxnQGubUqZ27I1x52nAI/s320/IMG_20131207_222105_678.jpg" width="320" /></a></div>
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These are the bearing blocks used in the gantry. Each one holds a round rod ball bearing bushing. The bushings are tight slip fits, so you can put them in by hand, but it does require some force to push though. Each of the bushings are held in with snap rings. Most of the dimensions on this printer are a mix of english and metric units. Linear slides are all metric, but screws and part dimensions are english. I wanted to use existing stock and screws for most of this project to keep my costs lower, otherwise I would have made every dimension metric.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtZ3fT90-E4R7FSz0XfuLibtFgJw6VAlj4TZ7OOa3Vx6IejMc_JtuJmuSjDSl7FNv3-YF838llCu7DdYOO3DS_xagMx_F9l5qc_BcG6TA-uJVHBpFZHngt1p2r3udnjdHCc43UUK4VoDs/s1600/IMG_20131208_194115_275.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtZ3fT90-E4R7FSz0XfuLibtFgJw6VAlj4TZ7OOa3Vx6IejMc_JtuJmuSjDSl7FNv3-YF838llCu7DdYOO3DS_xagMx_F9l5qc_BcG6TA-uJVHBpFZHngt1p2r3udnjdHCc43UUK4VoDs/s320/IMG_20131208_194115_275.jpg" width="320" /></a></div>
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Here are most of the components in the gantry. Locating dowel pins are not pressed into the bearing blocks or the blocks that hold the X axis rails.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCwET_KIR_f-E-lxW6OUSdUktowlWg5iYMQw8LdGZplFHpH-t5vsbcWB5HzTfGYELz_EgQdGIDTjwMSOG2vD6-M_64zBFU8KiV5SxlSG_V0Ys-H2Weqycq3sGWjrmY7ElLaMezYTCsGp4/s1600/IMG_20131208_163204_582.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCwET_KIR_f-E-lxW6OUSdUktowlWg5iYMQw8LdGZplFHpH-t5vsbcWB5HzTfGYELz_EgQdGIDTjwMSOG2vD6-M_64zBFU8KiV5SxlSG_V0Ys-H2Weqycq3sGWjrmY7ElLaMezYTCsGp4/s320/IMG_20131208_163204_582.jpg" width="320" /></a></div>
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The frame is made from MDF. MDF was chosen because it is pretty cheap, it cuts nicely on a CNC router, it is relatively dense, and it doesn't produce splinters like other woods. If I get around to paining the frame it will look even cleaner than it does now.</div>
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Eventually I will glue the frame together, but for now it's going to be held together with clamps. There are still a few features that need to be cut into the frame, so I want to be able to replace or modify the 6 panels.</div>
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Here is the servo mount. The motor is a 350KV outrunner motor that should be able to output 1200 watts. This is total overkill for the printer. This size motor is used because of the low KV which makes it easier to control at a particular voltage. It also eliminates the need for a gear box, which can introduce backlash to a system. The encoder is mounted on top. The gantry uses an H-Bot design. This design uses one loop of belt within the gantry. The servos can be stationary and mounted to the frame with this design. This makes the gantry much lighter than a traditional gantry design where each motor separately controls each axis. In the H-Bot design the position of the gantry is a linear combination of the two motor positions. The gantry moves in the X axis when both motors spin the same direction. The gantry moves in the Y axis when both motors spin in opposite directions. If only one motor is spun, the gantry moves equally in both the X and Y directions.</div>
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Here is the FPGA board and motor control board wired up to the system for testing. The final system will be wired in a much cleaner way...</div>
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I'll try to keep up to date on the progress over break. I have this and a number of other projects to start and complete, so I should post more often than during this semester.</div>
JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com3tag:blogger.com,1999:blog-4585776524802028435.post-39161778496791592412013-07-28T01:10:00.000-07:002013-08-18T02:15:30.450-07:00New Project - Mini Combat RobotFor a number of reasons we (the combat robot club at my school) have started work on a mini combat robot competition that will take place on campus. This summer we've worked on getting the competition ready for the coming school year. The first thing I started with was the drivetrain. I wanted to avoid making all of the gears as I have for many of my other motorized projects, so I looked for a cheap and easy to purchase solution. I found large RC vehicle (car, plane, boat, etc...) servos have very cheap replacement gear sets. I bought two sets of the largest common servo I could find. This gear set works with the HITEC 805 servo series.<br />
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All of my motorized projects now use brushless motors. They deliver the most power in the smallest package. They are also very cheap compared to other motors. These little transmissions use a set of 220 watt motors. Each motor is about 20mm in diameter and 40mm long. The only down side to these small motors is they spin very quickly which requires a large gear ratio to make them useful. Thankfully the servo gears make this gear ratio easy to obtain. I designed the maximum output torque of the transmission not to exceed the original servo's rated torque. This should prevent the gears from immediately stripping. Wear may become an issue because of the increased gear speed, but I'm not too worried about that because they're a cheap and easy to replace solution.<br />
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Since these transmissions are for a mini combat robot, the screws also have to be small. I had quite a few #2-56 holes to tap. As always I was afraid of breaking the tap, but in the end I tapped 24 holes without incident.<br />
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Dowel pins are used as a bearing for the intermediate gears. Everything except for the #2-56 screw is metric in this transmission (I didn't want to buy metric taps and screws when I already have a large stock of English taps and screws). The output gear takes ball bearings, which should make this transmission pretty tough and smooth.<br />
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Overall the transmissions look pretty beastly. I'm waiting on pinion stock for the motor gears to come in from an order. I'll test them once I can actually transfer motion from the motors to the rest of the gears.<br />
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The next step in the mini combat robot build process is to get the motor controllers designed (yes; I'm making the motor controllers from scratch) and to finish the chassis CAD.JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-49017263727020916342013-06-30T18:43:00.000-07:002013-08-17T18:48:11.195-07:00Desk Lamp FINISHEDNow that it's the summer, I finally had the time to finish the desk lamp. The combat robot destroyed any amount of free time I had. I had been using the lamp without the base for over a semester, while the half finished base just sat on my dorm room floor.<br />
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It took a creative setup to machine the other side. I used a 4 jaw chuck from a lathe and clamped it to the mill table. I also added a bolt in the center to hold the part flat to the chuck. The part seems to be flat within .002" which is pretty good because it doesn't matter at all for a desk lamp.<br />
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I put some cutting fluid on the part and I used compressed air to keep the chips from clogging up the end mill.<br />
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The final base looks perfect!<br />
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I snapped a couple photos of the lamp against a whiteboard. It makes a really good background for taking pictures.<br />
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I even set it up on my messy desk in my summer apartment.<br />
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It definitely goes well with my guitar. I'll need to work on making a desk and other furniture to go with the rest of the things I've been machining lately.<br />
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PROS<br />
-The LED is crazy bright. It lights up not just my desk, but also a good fraction of my room.<br />
-MEGA REACH! I can get amazing lighting on any part of my desk.<br />
-Aesthetics. I think this lamp looks amazing.<br />
-Low power consumption. Everyone loves going green now...<br />
-Runs colder. Most desk lamps will give you a nasty burn. This one is pretty warm, but I've held my hand on it without any problems.<br />
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CONS<br />
-The ball bearings in the base have too little friction. It swings around on its own on a non-level table.<br />
-Not dimmable. Sometimes its too bright. (I don't think my roommate appreciated it when I pulled all-nighters to finish homework.<br />
-It's fragile. Most of my projects are tough to damage... Not this one.<br />
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Overall this is a pretty sweet lamp. A number of people have asked if I am going to make more. I'll probably come up with a production version of the lamp, which gets rid of the CONS and reduces the material and machining costs. There are a few LED desk lamps on the market, but they all suck in my opinion. For now I'll keep using this as my main desk lamp and see how long it lasts (forever hopefully).<br />
<br />JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com1tag:blogger.com,1999:blog-4585776524802028435.post-74837027171782051632013-05-16T19:10:00.000-07:002013-08-17T19:11:39.603-07:00Heavy Weight Combat Robot - CompetitionCompetition was very interesting. We didn't do particularly well, but we did make it there with a complete and tested robot (not every team could say that). We also left with a complete and functioning robot (lots of teams couldn't say that).<br />
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During testing we discovered that the belt drive used to transfer torque between the motor and spinner was slipping pretty badly. The belt was designed to slip some. During an impact, the spinner stops almost instantaneously. The belt was meant to slip under this condition to protect the motor shaft. We heard from other teams that used the same motor for the same application that their shafts sheared when chained to the spinner. Our concept was good, but the implementation was bad. A belt tensioner was added between testing and competition. It helped, but it didn't fix the problem. We also added a belt dressing which was supposed to make it grip better. In the end it just made the belt disintegrate much faster.<br />
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Here's Robespierre right before competition. It looked pretty sweet. The others in our division saw that too. They also warned us that the first tournament would be a "learning experience"... they were right. We went up against two wedge bots. Since the belt was slipping the spinner wasn't able to gain enough kinetic energy to take out the opponents. Just like any vehicle, it can only takes one critical part to cause the whole thing to fail. 99% was good, but that 1% belt prevent it from being amazing. The carbon fiber arms broke off as we had guessed they would. otherwise, the robot received nothing more than a few scratches. We were proud we held up to the beatings delivered by the other robots. Sadly I don't have videos because I was part of the drive team.<br />
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A few things we did worked amazingly well. The brushless drivetrain saved a ton of weight. It was a risk that we took because it was an unproven technology in the heavy weight class, but it really gave us an advantage in building our robot. The magnets were also a big boost to performance. Our first match had the magnets on. The robot was firmly planted to the floor at all times. Our last match we didn't have the magnets (the judges were less than amused when a magnet fell off and adhered itself to the arena floor). That match we were jumping up in the air during impacts. It also let us get wedged.<br />
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The belly pan got fairly scraped up. I think it looks better with the scratches... it's battle tested!<br />
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I'm not really sure where to go with the PROS and CONS list.<br />
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PROS<br />
-It breaks stuff.<br />
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CONS<br />
-It's only use is breaking stuff<br />
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Overall the biggest things we need for the robot are improvements. There are minor fixes that need to be completed before the next competition to make it a real competition. Some are small changes like changing out the belt with something that grips better. Other changes are increasing the ground clearance and making a better magnet system (so they can't fall off during a match).JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-57276102797085879152013-05-16T17:09:00.000-07:002013-08-17T19:12:08.495-07:00New Project (finished too) - Heavy Weight Combat RobotI guess there aren't going to be any project updates for this project considering its already done. This is the first amount of free time I have had all semester... and it's finals week. At the beginning of the first semester of this school year a small group of my friends and I decided it would be a good idea for the school to have a combat robot club, with the ultimate goal of competing in the 2013 RoboGames competition. With a little bit of work we were able to obtain adequate funding from the school to do pretty much whatever design we wanted.<br />
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Originally we wanted to enter into the 110 pound middleweight competition, however after watching videos we decided this weight class was a little lame (very wrong conclusion, even the 3lb robots are scary and exciting to watch). After some group brainstorming and preliminary weight estimates for our design, we<br />
realized the 110 pounds wasn't going to happen, so we just switch to the 220 pound heavy weight class. Looking back, I kind of regret this decision because it made for twice the work, but I'm also glad we chose this weight class because there's a fairly small group of individuals that have attempted the 220 pound robots. It also really pushed me to put myself to my limit to get this project done while maintaining my grades!<br />
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One thing we wanted to do with the design was use components that teams don't currently use because either they're new and untested, or harder to use. These three sets of new components are as follows:<br />
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-Brushless motors<br />
-Li-Poly Batteries<br />
-Neodymium Magnets.<br />
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The first thing we decided to work on for testing was the brushless motors. These aren't just regular brushless motors, they're RC car brushless motors. The funny thing is that most people wouldn't consider these motors because they're designed to run RC cars that are only a few pounds. In addition, the motors are very small (around 1.5" in diameter, 2"-3" in length, and around 1 pound). Compared to the motors used on most combat robots in the 110 and 220 pound weight classes, these things are toys (most 220 pound combat robots use brushed motors that weigh upwards of 10 pounds and are 4" in diameter) The reason we thought these motors could work is that they had power ratings over 1800 watts, not far off from the big motors.<br />
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We decided to make a test platform to determine whether or not these motors were actually able to put out the power they advertised.<br />
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The idea for this platform was to measure the torque output over a range of different rotation rates while the motor was provided full power. Normally this is done by connecting the new motor to an existing one that has known parameters. We couldn't do this because we didn't have a motor that could spin 40,000 rpm and handle 2-3 HP. Instead I cooked up a platform of our own that tells the torque and rpm. There is an aluminum disk bolted to the motor. A neodymium magnet is spaced very closely to the aluminum plate. The neodymium magnet is held by an axle that is supported by ball bearings. The axle transmits torque between the magnet and a lever at the end. The lever is then placed on a scale.<br />
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The setup works by the same physics that cause a magnet to fall very slowly through a copper pipe. When the motor spins the aluminum wheel, the opposing neodymium magnet generates eddy currents in the aluminum (this is going to be a bad physics explanation, but bear with me). These eddy currents generate a magnetic field that opposes the magnet. The eddy currents turn all of the output power from the motor into heat because the aluminum has electrical resistance. The torque is transferred by the eddy current's magnetic field and the neodymium magnet to the lever arm. This torque causes the arm to press down on a scale. This allows us to measure the torque. The rotation rate is found by counting how many times a black stripe on the wheel passes by a light sensor. (Note that the setup uses some of the electronics from the "anti-gravity" robot that my roommate and I were constructing at the time.)<br />
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The system showed the motor was providing similar power outputs to the specifications. One mildly dangerous thing about the test setup was the temperature of the aluminum disk. Since the fixture is 0% efficient, all of the output power goes into heating the aluminum disk. Within a few seconds of testing, the disk was well above boiling (wet paper towels hissed as if they were touching a soldering iron)<br />
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The video shows a small piece of tape on the end of the motor shaft. The motor was surprising loud. Given that we verified the power output we decided to go with the brushless motors for their higher power to weight ratio. The only down side is that they need to be geared down a ton. ~40,000 RPM is not particularly useful on a combat robot drivetrain.</div>
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The weapon for our deign is a spinner. Spinners require massive amounts of horsepower to spin up within a reasonable amount of time. We bought the massive PERM motor. it can run up to 72 volts and have a peak power output of around 34 HP.</div>
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Even with only 12 volts I almost wasn't able to hold the motor down during start-up. We scored a good deal on the motor using ebay. It was sitting in someone's garage for a few years, but it was in perfect condition.</div>
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Naturally, the robot was drawn up before machining to ensure the parts all fit together and there wouldn't be any nasty surprises along the way.</div>
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I had trouble getting the colors to look good on the full render, so here's a contour render. It makes a great desktop background. (I've been making more of these contour renders because I think they look much better.)</div>
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I'll just include a bunch of pictures of the machining process. There were lots of cool parts. Since this was a school club project, we worked to get as many people involved in the production process. I was able to see many students go from having never seen or heard of a mill to being able to operate a CNC and make perfect parts.</div>
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This is the first time I ever used a water-jet. It made production of the large plates on the robot much smoother. This part was made in January, and was one of the first parts made for the robot.</div>
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Here you can see the motor on top of the belly pan. The belly pan greatly increases the shear strength of the chassis. It is also a great mount for the electronics. It is 34" x 22" x 1/8". This also shows how massive the spinner motor is compared to the rest of the robot. The limiting factor on the robot height was the motor.</div>
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After being back at school for less than 24 hours (came back from winter break), we already cranked out the transmission plates and some of the axles. In addition we picked up the gear stock for the transmission. One drive motor and motor controller are also in the picture.</div>
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We made a will call pickup from McMaster! (You can order on a Saturday and pickup the order an hour later!) Lots of screws. The metal came from Online Metals, but we put it in the McMaster box to keep the dorm room as clean as possible.<br />
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Here's our double vice setup for the chassis side rails. There's only one vice per mill in the school shop, so we had to jack the second vice from another mill. There are 4 of these parts on the robot. Lots of tool changes without an automatic tool changer is a horrible pain.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfREUOVq2LzBlYGQDQAoI5tAVrvUm78QXSHjUYZZOniREoAG3zri8oSLKo4NXyyVMn7Bk7CpggHFosIbA7QUAZbIjsWm0PykdsRDBJfwm5pTgX1E2u7qktkjhJ4DrMS4Y6_M6hStepA_I/s1600/2013-02-03_00-23-46_518.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfREUOVq2LzBlYGQDQAoI5tAVrvUm78QXSHjUYZZOniREoAG3zri8oSLKo4NXyyVMn7Bk7CpggHFosIbA7QUAZbIjsWm0PykdsRDBJfwm5pTgX1E2u7qktkjhJ4DrMS4Y6_M6hStepA_I/s320/2013-02-03_00-23-46_518.jpg" width="320" /></a></div>
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I used a machinable collet to hold the gears. The collet was bored out to the OD of the gear stock. This way the gear teeth were guaranteed to be concentric to the bore. This was much more pleasant than making custom jaws for the 3 jaw chuck.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWw_Kiufd8_G61-d-lDIEeyDgJZCEY_sa9aAmHfztZO9fclA4mmHeoYZ4mMZIZmCD0G24ijQNM_leQDSn_Kfp1-OzoUM0qxzZ_m7nB5VQ0JDRZe5nvzBim-upnmbal-4teXBmoE1MzokM/s1600/2013-02-03_20-11-11_536.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWw_Kiufd8_G61-d-lDIEeyDgJZCEY_sa9aAmHfztZO9fclA4mmHeoYZ4mMZIZmCD0G24ijQNM_leQDSn_Kfp1-OzoUM0qxzZ_m7nB5VQ0JDRZe5nvzBim-upnmbal-4teXBmoE1MzokM/s320/2013-02-03_20-11-11_536.jpg" width="320" /></a></div>
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Here is a finished gear stock. Buying 3 gears was more expensive than buying a whole gear stock, so for the 64 tooth 32dp gears we had lots of spare material.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmnWTDa6WHmAPXXHE7NwtlFwz-tnDJBX108eHEHjP1Ui16AbAh5U-kJksv89SqTnaOxzr-9RqaY5UGkl95Y5eZcEET1eeXg_ENMqUT83xSB-_OEmJWtNEzpn6tSYfo2td8XxiB2HxCaxI/s1600/2013-02-03_20-26-14_135.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmnWTDa6WHmAPXXHE7NwtlFwz-tnDJBX108eHEHjP1Ui16AbAh5U-kJksv89SqTnaOxzr-9RqaY5UGkl95Y5eZcEET1eeXg_ENMqUT83xSB-_OEmJWtNEzpn6tSYfo2td8XxiB2HxCaxI/s320/2013-02-03_20-26-14_135.jpg" width="320" /></a></div>
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The cutoff tool was used to remove most of the material, but the horizontal bandsaw was used to cut each blank off of the stock. This way stock could be supported by the live center at all times while inside the lathe. The rest of the facing and boring was done with the custom bore collet.</div>
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<iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.blogger.com/video.g?token=AD6v5dxiQ3SyNFEuOyRPnUdS7NRzYnQsLkddV-RdozBi6CH8hBKN1GlPuWR85b-el4mo0zoQ6yV9Y9X9fqLH4OHG3g' class='b-hbp-video b-uploaded' frameborder='0'></iframe></div>
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Gear stock makes great noises...</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9cUTU7Iv6vW6wBPi62Ozjd7rK642NJofCha3wOhAcGXYeXkvZf-xMhbYGWjFRm_KYHcANrhCDEwzV-PeSNzTMdL0RYRYg8U_TXG9GGKKLB1P-YcZyjw2d14gZcv2sWukj4Mh_qZZIW24/s1600/2013-02-07_21-28-59_341.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9cUTU7Iv6vW6wBPi62Ozjd7rK642NJofCha3wOhAcGXYeXkvZf-xMhbYGWjFRm_KYHcANrhCDEwzV-PeSNzTMdL0RYRYg8U_TXG9GGKKLB1P-YcZyjw2d14gZcv2sWukj4Mh_qZZIW24/s320/2013-02-07_21-28-59_341.jpg" width="320" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9AA3AJh9GSFyuf5yq-RhA2e4EQFDXRcIpe9SGfUZIuH2kORQPCBmMyTx7N2XCGRCFyyFPtHBawtQzH62FBij-rMy6uHEi84jvZI2eGzzbF20fIX7c-Xm3Q-tT43DTiTs74r0_SUQYwNU/s1600/2013-02-07_22-42-40_801.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9AA3AJh9GSFyuf5yq-RhA2e4EQFDXRcIpe9SGfUZIuH2kORQPCBmMyTx7N2XCGRCFyyFPtHBawtQzH62FBij-rMy6uHEi84jvZI2eGzzbF20fIX7c-Xm3Q-tT43DTiTs74r0_SUQYwNU/s320/2013-02-07_22-42-40_801.jpg" width="320" /></a></div>
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I designed the transmission to use as many of the same tooth number gear as possible. This way I could use the gear stock to its fullest. I made a full set of spares just in case some catastrophe happened during competition.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVHPub59tLgRekQFbg79yvAtLddprppHVkE-FJ_Q21gG4fDQt9h0xIe35oL-AzY7BvDHCDMq_u3_Lj8C4bysNawgsebrlbvSBtkzcELEe0vKWNFZ_GpsaXobS8Z5vghhBDsaz7xNO7W4M/s1600/2013-02-03_22-55-51_933.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVHPub59tLgRekQFbg79yvAtLddprppHVkE-FJ_Q21gG4fDQt9h0xIe35oL-AzY7BvDHCDMq_u3_Lj8C4bysNawgsebrlbvSBtkzcELEe0vKWNFZ_GpsaXobS8Z5vghhBDsaz7xNO7W4M/s320/2013-02-03_22-55-51_933.jpg" width="240" /></a></div>
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In just about 2 weeks we managed to make it this far. This is amazing considering we all have copious amounts of homework and there is only one CNC mill and lathe. The limiting factor has really been the single CNC mill. The manual machines are in such poor condition that even facing stock turns out poorly. All milled parts on the robot have to pass through one machine.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGztTHM-sP4AXVIR97wH-fL3Y0K4o7ZnwNb7rkd8ZeyXbCE4cYqnOQQjgPN0KSB0acvm1PfFyX2GpG4UrB_bxvbdekCZWO7smlvJ0VING53jtA07ktnQ76jgPKAyWiFDHnN6VksVJlDLs/s1600/2013-02-09_23-15-56_519.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGztTHM-sP4AXVIR97wH-fL3Y0K4o7ZnwNb7rkd8ZeyXbCE4cYqnOQQjgPN0KSB0acvm1PfFyX2GpG4UrB_bxvbdekCZWO7smlvJ0VING53jtA07ktnQ76jgPKAyWiFDHnN6VksVJlDLs/s320/2013-02-09_23-15-56_519.jpg" width="240" /></a></div>
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Thankfully I didn't cause this crash. That was 1.5" diameter stock. The tool holder was a little messed up afterwards, but thankfully there was no harm to the machine.<br />
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PRO TIP: Watch where you extend your stock relative to the zero of the machine. The program was written to face off the first .1" of the stock. If the stock is extended past that by lets say.... an inch or two, the machine rapids into the part.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1yLgpBw2d0CosehPyf1KYmsHYIXTyec6dWUdF_socQduyy_qIiGS6QKAiVenL3mRNs8v6lFk8NzgV7xFgJ3zmXDDhxKhsX1FY9sG3KtrqsrDB036L6_lXhKen7P33CyHudNhvIAcjEWs/s1600/2013-02-15_21-52-45_57.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1yLgpBw2d0CosehPyf1KYmsHYIXTyec6dWUdF_socQduyy_qIiGS6QKAiVenL3mRNs8v6lFk8NzgV7xFgJ3zmXDDhxKhsX1FY9sG3KtrqsrDB036L6_lXhKen7P33CyHudNhvIAcjEWs/s320/2013-02-15_21-52-45_57.jpg" width="320" /></a></div>
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The crash didn't really set anything back (aside from morale). The hubs for the wheels were made in a few hours. We used 3" diameter wheels. This reduced the amount of gearing required for the transmissions. The cool thing is that the chassis is so short that the wheels still stuck up past the top.</div>
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<iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.blogger.com/video.g?token=AD6v5dzh_7l_xxom_0lHmaaBAyy-lJAlbpEHtvgXHfA5XVjoLB6VspYQzsEfdhIj54eQTxJXe7tyjXf-LTEulFuhzQ' class='b-hbp-video b-uploaded' frameborder='0'></iframe></div>
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A quick rolling test verified the chassis could roll. We added some cardboard boxes to make it look cooler... not sure if we succeeded.</div>
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I flew back home to get the rest of the water-jet parts made. Lots of 3/8" 7075 aluminum plate and 1/2" 6061 aluminum plate.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqFEcZ1h7e0_I7SRrKidyoj7cE_KESub2VXWAg7gi1OAkV5A1UtjHGYPh7cYysT4gmzJJAK0TXZu5HO1dmiqIN2xgv-VNqFyBE06fllJ5E2GLw4UBOI-bdFpev8Pdruxqcp-zJKY6Dwrs/s1600/2013-02-22_11-25-34_873.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqFEcZ1h7e0_I7SRrKidyoj7cE_KESub2VXWAg7gi1OAkV5A1UtjHGYPh7cYysT4gmzJJAK0TXZu5HO1dmiqIN2xgv-VNqFyBE06fllJ5E2GLw4UBOI-bdFpev8Pdruxqcp-zJKY6Dwrs/s320/2013-02-22_11-25-34_873.jpg" width="320" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiE3zIQ_ksw5jpAJ6M8NdlIl7hTK-C9gLU6-FKLV5IdS4MNvkqWXMM9QNxrtFoTrUI97f5AHKJjZyjQQaElv4TZDj-KfFRMsLlrmrNXtjnQ4lXoPRqhec1r93PN-_X6GhhsHK9ZJB08rCE/s1600/2013-02-22_11-29-25_726.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiE3zIQ_ksw5jpAJ6M8NdlIl7hTK-C9gLU6-FKLV5IdS4MNvkqWXMM9QNxrtFoTrUI97f5AHKJjZyjQQaElv4TZDj-KfFRMsLlrmrNXtjnQ4lXoPRqhec1r93PN-_X6GhhsHK9ZJB08rCE/s320/2013-02-22_11-29-25_726.jpg" width="240" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVGJCRBbRINWNYP82E-Et1_R71ZpGfcz0L1TiAf_-aJKkeTqHVVr-sNkTDfCnwoYBQQViuW6Un-gf9LcjAk1aKFL9HXym1BMggXnZWpVPKg1IIXCSs60yDHMAkojvv92RVuqjLMGyNS5o/s1600/2013-02-22_12-00-56_693.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVGJCRBbRINWNYP82E-Et1_R71ZpGfcz0L1TiAf_-aJKkeTqHVVr-sNkTDfCnwoYBQQViuW6Un-gf9LcjAk1aKFL9HXym1BMggXnZWpVPKg1IIXCSs60yDHMAkojvv92RVuqjLMGyNS5o/s320/2013-02-22_12-00-56_693.jpg" width="320" /></a></div>
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This is one of my favorite pictures from all of the machining.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoCD_cFpX0pLf6mLagx_aM0JMl39WLaScPjHw8_HFaj_jWCDnh3m78JbbxxGCWj4LbUmic_8xv4ri_h30jgAbG5A8M634IBCrhZxAm60vp6ZaHO2-tOscpY5B9IRCCLRmSAcYSWaZQI6A/s1600/2013-02-22_15-22-17_800.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoCD_cFpX0pLf6mLagx_aM0JMl39WLaScPjHw8_HFaj_jWCDnh3m78JbbxxGCWj4LbUmic_8xv4ri_h30jgAbG5A8M634IBCrhZxAm60vp6ZaHO2-tOscpY5B9IRCCLRmSAcYSWaZQI6A/s320/2013-02-22_15-22-17_800.jpg" width="320" /></a></div>
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Yeah... the spinner is pretty large.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8mrF18wzEFFq_klKYwNE0RiXV8y1uYOi_WDOBNQhtwNeUv5p0wZHppEdq31sW-MPMBydamIuGQQI8uZUegSJw6bG0JdLl1OUfw_DvLklr0zBLoRWhC_h7BcpvFm8yBIzoUWjcPvL5jfQ/s1600/2013-02-22_15-24-09_723.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8mrF18wzEFFq_klKYwNE0RiXV8y1uYOi_WDOBNQhtwNeUv5p0wZHppEdq31sW-MPMBydamIuGQQI8uZUegSJw6bG0JdLl1OUfw_DvLklr0zBLoRWhC_h7BcpvFm8yBIzoUWjcPvL5jfQ/s320/2013-02-22_15-24-09_723.jpg" width="320" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGiNNQgtrKGcQRJ5iUHaKx04WvvCN5zpd-ZK1xQtHJMuXO-Dsq2tcfjTwKkccog68n_8nrIOnVx_EtNI7z0iECmwJ4ng4-8Ij_HMDHhS0drfZ6ahoZIs1CmKcwqjUBAQuAvWbRycp3hqU/s1600/2013-02-25_16-55-07_80.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGiNNQgtrKGcQRJ5iUHaKx04WvvCN5zpd-ZK1xQtHJMuXO-Dsq2tcfjTwKkccog68n_8nrIOnVx_EtNI7z0iECmwJ4ng4-8Ij_HMDHhS0drfZ6ahoZIs1CmKcwqjUBAQuAvWbRycp3hqU/s320/2013-02-25_16-55-07_80.jpg" width="320" /></a></div>
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A couple hours worth of water-jet time made the biggest jump in completeness for the robot.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibq9U4LgsUxF_Oc0ljqI0I4ebadQJfVM1Qeqt8xiq9C4_WjZo2nu8pf_3sn8rr0CThT-7AoDasqzAFeHKG8_JdZXstuaPsDKVLkej6hvb0oOhasjzzZTkqRg3tucONoJtzQ__Db8f-mDo/s1600/2013-03-01_17-37-05_96.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibq9U4LgsUxF_Oc0ljqI0I4ebadQJfVM1Qeqt8xiq9C4_WjZo2nu8pf_3sn8rr0CThT-7AoDasqzAFeHKG8_JdZXstuaPsDKVLkej6hvb0oOhasjzzZTkqRg3tucONoJtzQ__Db8f-mDo/s320/2013-03-01_17-37-05_96.jpg" width="240" /></a></div>
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I got to use my insert endmill again (GMT tools are really awesome in looks, performance, and price). It's pretty boss.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhucIcM8B95T7-eYqSEdShBcdgaSmSM6Xl7dDaHCW4R2X9fhjjkLqwkCT-022mQ09Er3q24BlOA_b-PemTNCFrzS2y4WCSobixTIa302rUvHAktIX7eVfvTyVTjTxvKhkLOStNJX_yZtq8/s1600/2013-03-01_23-06-00_516.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhucIcM8B95T7-eYqSEdShBcdgaSmSM6Xl7dDaHCW4R2X9fhjjkLqwkCT-022mQ09Er3q24BlOA_b-PemTNCFrzS2y4WCSobixTIa302rUvHAktIX7eVfvTyVTjTxvKhkLOStNJX_yZtq8/s320/2013-03-01_23-06-00_516.jpg" width="240" /></a></div>
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These bearing blocks are pretty large compared to the mill. The bearings are 70mm ID tapered roller bearings. Considering they handle all the damage potential, they need to be pretty strong. I also realized how much the student CNC mill needs flood coolant and an enclosure. removing copious amounts of material takes forever.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgq07LPaVNI_LFGOl2NL6Aki5R-kqXdwlYLtxF699XeBhlhn9SqlaMPd14stZq-XwUaZBibxs7cVMRkU13WOXqdXorP5FaxnYacNI_iTpCw2q6a79OXAtrPmiM5nZT5_mg1Y8Eh6b_JIkQ/s1600/2013-03-07_22-35-37_127.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgq07LPaVNI_LFGOl2NL6Aki5R-kqXdwlYLtxF699XeBhlhn9SqlaMPd14stZq-XwUaZBibxs7cVMRkU13WOXqdXorP5FaxnYacNI_iTpCw2q6a79OXAtrPmiM5nZT5_mg1Y8Eh6b_JIkQ/s320/2013-03-07_22-35-37_127.jpg" width="320" /></a></div>
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The finished wheel assembly looks really awesome. The sprockets were cut on an EDM machine. All of them were cut in one stack, so it wasn't a waste of machine time.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLPBduFM_x5Tw95u66varez4fxMSVTB79-xRC2U94btUS0QATFy4XiyLtgGctcrzQCQa0Bu8G6z6JUKoQlXdbNify3WEBD05uv5RgQdnS7nS7Dbd1onR8aK4r7Q-jRjF6AiINpC9QYkPY/s1600/2013-03-08_00-57-22_564.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLPBduFM_x5Tw95u66varez4fxMSVTB79-xRC2U94btUS0QATFy4XiyLtgGctcrzQCQa0Bu8G6z6JUKoQlXdbNify3WEBD05uv5RgQdnS7nS7Dbd1onR8aK4r7Q-jRjF6AiINpC9QYkPY/s320/2013-03-08_00-57-22_564.jpg" width="240" /></a></div>
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I made chain tensioners, but hoped the chassis wouldn't need them. I lucked out and the chain was perfect. #35 chain is pretty robust and can take some slop without any problems.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZs3Cslend2_BtsL2fcEhtKQvEJe7oisYoXxwjUwIIFmvEIDAhbelBOJ0jJX5ZZ4fDUONgHgYF00u0kaqb1_8zR1D4nNqQQSgO4NiXNNTtQykKP15nmIbti3bdlNtWeo5DWXHJ5_QKj3U/s1600/2013-03-09_22-03-10_930.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZs3Cslend2_BtsL2fcEhtKQvEJe7oisYoXxwjUwIIFmvEIDAhbelBOJ0jJX5ZZ4fDUONgHgYF00u0kaqb1_8zR1D4nNqQQSgO4NiXNNTtQykKP15nmIbti3bdlNtWeo5DWXHJ5_QKj3U/s320/2013-03-09_22-03-10_930.jpg" width="320" /></a></div>
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This is starting to look like a real battlebot.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiaxC2Jr5ZH0w1jLTBBQwg9v6eHgEQPg_4SZH7Q3oUsAiMivkiYmJTpG9Gky5CIqyhcVQtIf-O4qetS6Lr9pvTGQcfGfwTyR0rVP9Vv5Nbx9x42d8k0hL8ZHOfBOLeXKC1mdLVJ3XVSpE0/s1600/2013-03-23_01-08-40_636.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiaxC2Jr5ZH0w1jLTBBQwg9v6eHgEQPg_4SZH7Q3oUsAiMivkiYmJTpG9Gky5CIqyhcVQtIf-O4qetS6Lr9pvTGQcfGfwTyR0rVP9Vv5Nbx9x42d8k0hL8ZHOfBOLeXKC1mdLVJ3XVSpE0/s320/2013-03-23_01-08-40_636.jpg" width="320" /></a></div>
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A quick drive test greatly boosted morale (morale was good before the test, but it was super high after the test). The robot easily carried 3 people. The acceleration skids the wheels on the floor. The massive rpm of the motor makes the gears scream. It sounds pretty mean. This also proved we didn't screw ourselves by going with the brushless motors. The next priority was to build the rest of the spinner.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijg7PiGFCQ6cFh-GHx3Ov9dNLh9Pc6hEOI4TgaRXT4FCY0bhmFhvVoy9uqUxiHcjzOA9RKhuNB4vtbiiFIAHdaLjt-pqCyo9MnWOREk_ae0fkz9ElMRO1gXtbfNFRXPMyI0seK_ZE_U88/s1600/IMG_20130324_234745_214.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijg7PiGFCQ6cFh-GHx3Ov9dNLh9Pc6hEOI4TgaRXT4FCY0bhmFhvVoy9uqUxiHcjzOA9RKhuNB4vtbiiFIAHdaLjt-pqCyo9MnWOREk_ae0fkz9ElMRO1gXtbfNFRXPMyI0seK_ZE_U88/s320/IMG_20130324_234745_214.jpg" width="320" /></a></div>
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The stock was only wider than the 3 parts by .03" and thicker than 2 parts by .01". We had to get creative. This was very material wasteful, but considering the original 27 lb slab of 7075 was from a metal recycling place for only $2 a pound, I was cool with machining away half of the material.<br />
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Getting closer to the final assembly. Finishing the robot in time for competition is a little more stressful that we had originally thought. The CNC mill kept needing to be used for class projects, which killed the productivity.</div>
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The spinner looks pretty menacing on the robot. Now all it needs are the hammers and tool steel blades.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4_Eg6VUfsb7Fkys5yawdQtoGnFG_vzjGbfDBPi6DZepOLHxUdWEgdwA5ufkRlQHuzHofogC7Liq4NclNYNIf89PpRbjmg2yAY1cbHZt3IV_yhaESTYsMZrq2cBPjA-YomYwWmpVzDpyA/s1600/IMG_20130407_164547_774.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4_Eg6VUfsb7Fkys5yawdQtoGnFG_vzjGbfDBPi6DZepOLHxUdWEgdwA5ufkRlQHuzHofogC7Liq4NclNYNIf89PpRbjmg2yAY1cbHZt3IV_yhaESTYsMZrq2cBPjA-YomYwWmpVzDpyA/s320/IMG_20130407_164547_774.jpg" width="320" /></a></div>
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This shows how the parts interlock. The hammer is locked by geometry to the arm plates. This ensures the bolts don't need to take the shear force from the impacts. The 7075 of the arm corroded some which is why it is so much darker than the 7075 used in the tie rod blocks above the hammer.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSoJ3SAq9KB6NTND3thMn96zeUuRMbeILedAK3qzSGudrJT59p9ScKbCs6UKKMp9AbJre5HqcgQFCWWz62sP7lp-St7OTzxD7vOCHd_GDo2NdGcz_baIAouuYq46iYYym_MI-NXQ8ww0s/s1600/IMG_20130412_223456_205.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSoJ3SAq9KB6NTND3thMn96zeUuRMbeILedAK3qzSGudrJT59p9ScKbCs6UKKMp9AbJre5HqcgQFCWWz62sP7lp-St7OTzxD7vOCHd_GDo2NdGcz_baIAouuYq46iYYym_MI-NXQ8ww0s/s320/IMG_20130412_223456_205.jpg" width="320" /></a></div>
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I cut the protective lexan shields for the electronics using the CNC router. It was surprisingly easy considering some of the troubles I have had with the router in the past (my longboard).<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDzrq4o23YzYC19jAliZ0CFJT9X2XKvYY8IUMlhJj0u8zBYGaji36lkSf-ovMNbjMu1dS0zuedZmNJ0vZY0N-nUB8HZgSZC33GNNJ6f5N4T25Mc74zIAi-H1raJiUgjytRmu3NbSKqj94/s1600/IMG_20130413_044017_609.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDzrq4o23YzYC19jAliZ0CFJT9X2XKvYY8IUMlhJj0u8zBYGaji36lkSf-ovMNbjMu1dS0zuedZmNJ0vZY0N-nUB8HZgSZC33GNNJ6f5N4T25Mc74zIAi-H1raJiUgjytRmu3NbSKqj94/s320/IMG_20130413_044017_609.jpg" width="320" /></a></div>
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Carbon Fiber tie rods. These parts connect each of the arms to improve the overall strength. We knew carbon fiber might be a mistake, but we used it anyways because it was light and we had it. It was a mistake, but we didn't find out until competition.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJWbFwK-5azaHtg8PRp9ZNenEQ-HZ266ly7mYMKONHGiKc8W7aKqYkCW9u3KJdlJj4IzZubi_I24kcQWbS3Dv7Y8kDcFjkmXijLLCbx0X_FLQzOStA4MA3neBl_pbh67k_dGfahzOq968/s1600/IMG_20130413_044842_467.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJWbFwK-5azaHtg8PRp9ZNenEQ-HZ266ly7mYMKONHGiKc8W7aKqYkCW9u3KJdlJj4IzZubi_I24kcQWbS3Dv7Y8kDcFjkmXijLLCbx0X_FLQzOStA4MA3neBl_pbh67k_dGfahzOq968/s320/IMG_20130413_044842_467.jpg" width="320" /></a></div>
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The spinner looks really awesome... mostly because its shiny. This weekend was a major push because testing was scheduled for that Sunday. We got access to a gravel pit across from the school to ensure we could be a safe distance from the robot.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg34XbE2sDquIEau5KU507Pz6KLgIU8THGMiPvmHXgtjaI8-ycmXFbngJrVTIDgSTXu7r4h1SFWg516vfxYFkjSJd6fwJPkpT5PGoGWnDDhDPPuow6BqeYfrOJ5MI46csF5RLRyjySv3hQ/s1600/IMG_20130413_060601_988.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg34XbE2sDquIEau5KU507Pz6KLgIU8THGMiPvmHXgtjaI8-ycmXFbngJrVTIDgSTXu7r4h1SFWg516vfxYFkjSJd6fwJPkpT5PGoGWnDDhDPPuow6BqeYfrOJ5MI46csF5RLRyjySv3hQ/s320/IMG_20130413_060601_988.jpg" width="320" /></a></div>
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Remember the idea of adding neodymium magnets that I talked about at the top of this post?<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEisZlIAcBJsuzJ5HQfSBD4FQFYtxj5M0-WE7ZEXFQ0kUzpPck0Ec5o5ol3OEScaeOH3VAy_pzNJJAwTas7bhL4tY0v6ol0oBkfbgVptaXhECqD3CmvntRKk3wLqwv2ezaZCKb-LCHYf7k4/s1600/IMG_20130413_145757_081.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEisZlIAcBJsuzJ5HQfSBD4FQFYtxj5M0-WE7ZEXFQ0kUzpPck0Ec5o5ol3OEScaeOH3VAy_pzNJJAwTas7bhL4tY0v6ol0oBkfbgVptaXhECqD3CmvntRKk3wLqwv2ezaZCKb-LCHYf7k4/s320/IMG_20130413_145757_081.jpg" width="240" /></a></div>
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Yeah they work... We were able to jump on the chassis and not have it fall from the thin sheet metal door. (The concept of adding additional down force led us to design the "anti-gravity" robot)</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgr1wDH6XaPtPb5wBQRUEAKD85UqED3_eWdXYRTFP7U8B26PIw9UjlEwSKDhCvVdyCv0XgrX36Jh6horRflN__nCpTYEM47pvwH2SAPwUDvVHe05kw-WYNIXY946bJ8JF47XkhRHQEqG10/s1600/IMG_20130413_151713_380.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgr1wDH6XaPtPb5wBQRUEAKD85UqED3_eWdXYRTFP7U8B26PIw9UjlEwSKDhCvVdyCv0XgrX36Jh6horRflN__nCpTYEM47pvwH2SAPwUDvVHe05kw-WYNIXY946bJ8JF47XkhRHQEqG10/s320/IMG_20130413_151713_380.jpg" width="320" /></a></div>
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We also tested it on top of 1" thick steel plate at the school construction site to make sure it could drive with the additional couple hundred pounds of down force. It didn't really seem to notice the extra force, but we had trouble removing it from the ground.</div>
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Greasing the spinner bearings... YUMMY<br />
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We finally made the S7 tool steel blades.<br />
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And heat treated them too... (had to pull 4 all nighters in a week to get to this point because the robot had to be finished for testing the following day)</div>
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We also have a robot name!</div>
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Considering this was the first combat robot any of us had ever built, we needed to test it. We needed a safe place to test it where we could control who was going to be near the robot. In addition we wanted no property near it just in case there was flying debris or a catastrophic spinner disintegration. We got permission to use the gravel pit next to the school. It's a giant gravel pit that takes up a few square blocks. No debris could escape.</div>
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The tool steel blades look pretty scary. The mac was broken, so it was cool to smash. You can imagine what shape the mac was in after the impact.</div>
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The mac was eaten up pretty quickly.</div>
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I like how the CD drive ejected. It isn't visible in the pictures, but there were a number of IC chips that flew off the board. The impact G's were so high the surface mount components flew off the boards! That's pretty cool.</div>
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Needless to say, the microwave didn't stand a chance.<br />
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The microwave got smashed in one solid hit.<br />
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The tool steel spikes seem to do their intended job pretty well.</div>
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Testing was a great way to prepare for competition, mostly because it was fun.<br />
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I'll summarize the competition in another post</div>
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JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-11727969365775459302012-12-15T16:37:00.000-08:002013-05-14T15:15:17.400-07:00Guitar FinishedThe guitar is finally done! It has been more than 2 years since the first line was drawn on my computer, which isn't bad considering it was originally an exercise to see what I could CAD. The finishing parts I made since the last post were the pick guard, the and the potentiometer knobs.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzmRD3wmbW2YHrCju7HIqjE3vuJz0WqrMDKWQ_BiJplbJmpXZxnFth6gQrVzGpN5WAnwfdt-xc-gjZocQQaL7D7QzlAcxYPkl9reJF1qDMRtGmnVtUAbS2slmmeUAnZVbLsp5OFll1NT4/s1600/2012-11-16_17-40-37_205.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzmRD3wmbW2YHrCju7HIqjE3vuJz0WqrMDKWQ_BiJplbJmpXZxnFth6gQrVzGpN5WAnwfdt-xc-gjZocQQaL7D7QzlAcxYPkl9reJF1qDMRtGmnVtUAbS2slmmeUAnZVbLsp5OFll1NT4/s320/2012-11-16_17-40-37_205.jpg" width="320" /></a></div>
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The pick guard was pretty straight forward to machine. I had to use a fixture plate to hold it because my stock was the same thickness as the part. I also used a countersink to add a really clean chamfer around the part. It took a little longer to machine, but makes it much more friendly to handle. I would prefer not to injure myself when rocking out.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoD3SIlEURtVOnZ8qSxzUKqyOPilluIjzb5Nl7Tm2dFTJCTHqVpS1C6zJJsHhDna9oRB9O1u1PSwF51QFOF-PrKJbI-CsrwmVsMH3yqpRdO9X-63aOnyjqvaejnGz5J4qVFbyETKrHCEQ/s1600/2012-12-14_13-33-16_461.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoD3SIlEURtVOnZ8qSxzUKqyOPilluIjzb5Nl7Tm2dFTJCTHqVpS1C6zJJsHhDna9oRB9O1u1PSwF51QFOF-PrKJbI-CsrwmVsMH3yqpRdO9X-63aOnyjqvaejnGz5J4qVFbyETKrHCEQ/s400/2012-12-14_13-33-16_461.jpg" width="400" /></a></div>
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The knobs were pretty fun to machine. I used my boring bar for all of the lathe work so there wouldn't be a need to zero the tool more than once on the manual machine. I also needed to turn tapers for the custom collets inside the knobs. Using the same tool for both the internal and external taper without changing the compound tool post position ensured perfect grip.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSQ1BH6i7g6Pc4l37bmjkDenZhEW-mqB2mQnvMFGuTFrNos7EyHVGfiSHVzURYjvDszq66l-WV3z58Z0EjGTgU6hgtP3AEL2yabHpKWOusrpLJBmhatm6_yOyT_8hLFcr1NVwD6xTgwWM/s1600/IMG_20130513_204502_395.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSQ1BH6i7g6Pc4l37bmjkDenZhEW-mqB2mQnvMFGuTFrNos7EyHVGfiSHVzURYjvDszq66l-WV3z58Z0EjGTgU6hgtP3AEL2yabHpKWOusrpLJBmhatm6_yOyT_8hLFcr1NVwD6xTgwWM/s320/IMG_20130513_204502_395.jpg" width="240" /></a></div>
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The collet potentiometer knobs are much better than the lame setscrew or press fit types. The bolt circle on the top also looks really cool.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBls5bXXx19m0qoO6fMTm2Ztyr4Di0OQQZ6EK61d19rDX_CL5N4SmppaZ5JTsFbEydx6_3oI4k2LWIz_a3dIzeJY02hK4nqtKzUf72vSx97aF72YxX0v0UJfq8cbGd4G6SxcKPEmZITbs/s1600/IMG_20130513_204533_012.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBls5bXXx19m0qoO6fMTm2Ztyr4Di0OQQZ6EK61d19rDX_CL5N4SmppaZ5JTsFbEydx6_3oI4k2LWIz_a3dIzeJY02hK4nqtKzUf72vSx97aF72YxX0v0UJfq8cbGd4G6SxcKPEmZITbs/s320/IMG_20130513_204533_012.jpg" width="320" /></a></div>
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All of the polished parts look really great. The bridge is probably my favorite part of the guitar. Everything fit together perfectly and the screws fit in seamlessly with the different components.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1wbtJ_iSeRrJjt1tGBcNmL_CR-mP8HYlsgwUbXQexYnXn6kXGWWBXPBEFEqdoic3g3DDividssLrI4Af-emh_SDxC-a1Q4H52uhjnp-VCQ5vGZI5DDD81I7lzlgfbDYq2yD2mGjl2PrM/s1600/IMG_20130513_204615_040.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1wbtJ_iSeRrJjt1tGBcNmL_CR-mP8HYlsgwUbXQexYnXn6kXGWWBXPBEFEqdoic3g3DDividssLrI4Af-emh_SDxC-a1Q4H52uhjnp-VCQ5vGZI5DDD81I7lzlgfbDYq2yD2mGjl2PrM/s320/IMG_20130513_204615_040.jpg" width="320" /></a></div>
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The pickups fit nicely with the pick guard. The only thing missing is the addition of my symbol to the center. Once I get a proper sized endmill I'll add it onto the part.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-dt-dapq49q9YlvPB-i31oJ3CyKSecED4JG2j3MiJ7Rkx8S-7vCMIe1auuMfloshzQlJkJ0wFiHHgiS8t5nvVqQvULZ-II0Px2tb9KmhzpvNFGFHjPAn50akFAjWsczk0wE70vpT9-yA/s1600/IMG_20130513_211416_189.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-dt-dapq49q9YlvPB-i31oJ3CyKSecED4JG2j3MiJ7Rkx8S-7vCMIe1auuMfloshzQlJkJ0wFiHHgiS8t5nvVqQvULZ-II0Px2tb9KmhzpvNFGFHjPAn50akFAjWsczk0wE70vpT9-yA/s640/IMG_20130513_211416_189.jpg" width="640" /></a></div>
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The completed assembly is pretty classy looking. It turned out very different from the original sketches I made as part of the CAD exercise, but I really like the way it looks now.<br />
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Here's my list of pros and cons for the final product.<br />
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Pros<br />
-Sounds better than my other guitars. (probably the nice pickups, but it might be the solid aluminum construction)<br />
-Don't need to worry bout breaking it (I don't have a case yet, but wrapping it in a towel to protect from scratches seems to be totally adequate)<br />
-The neck feels really nice. The 3D profile machined ridges make a really neat texture.<br />
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Cons<br />
-The weight balance is pretty bad. The body is well pocketed out, but the neck and head are fairly solid. Even with the extended body shape, the neck still tends to tip down when playing with a strap.<br />
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I could only come up with one con. That's pretty good! Since the side plates are easily replaceable, I can always quickly readjust the balance with a set of shiny new plates.JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com1tag:blogger.com,1999:blog-4585776524802028435.post-84947664068969469712012-12-02T22:13:00.000-08:002013-08-17T18:17:23.675-07:00New Project (finished too) - "Anti-Gravity" RobotWe have a fun little competition at school called the Awesome Things Competition. There aren't really any rules, you just have to make something cool and it gets arbitrarily judged by a few professors who volunteer to see all of the cool projects. If you enter you get $100 to make your project. You can spend more if you want, but most people try to keep it within that budget in the spirit of competition. The winner collects another $100.<br />
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My roommate and I were brainstorming ideas for another project we are working on, and we had a funny idea. Could a fan be used to let a robot drive up walls and on ceilings?<br />
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We started our design by doing some simple math: addition and subtraction! We added up the weights of the components we wanted on the robot (motors, fan, batteries, chassis, wheels, etc..) and subtracted the thrust from the fan. If our number was negative we were good! We figured the thrust from the fan had to provide the normal force for the robot to drive. We figured any suction effects from the fan would add to a factor of safety to ensure the robot wouldn't drop.<br />
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We wanted the project to be super fast to make, so we laser cut all the custom parts from acrylic and used glue to hold them together. We reused transmissions, motors, wheels, and electronics from a robot used in a freshman engineering elective we both took. We only purchased the acrylic sheet, radio, batteries, and fan. Lots of blue tape was used to hold the thing together.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgMenvqqpphKy-ia5q0tHH1DWJSX-s0iRHHLVvF0dcaLnl1kgFU9WmqNZKer1D81uweO4HWuVN2-ry5afi_LQwcR1BZMcnFmSsbr2NsRhfZCuKwM6tKUY7JmNIdZtvZLWz3_rUWrMR1Rs/s1600/2012-11-16_13-42-43_457.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgMenvqqpphKy-ia5q0tHH1DWJSX-s0iRHHLVvF0dcaLnl1kgFU9WmqNZKer1D81uweO4HWuVN2-ry5afi_LQwcR1BZMcnFmSsbr2NsRhfZCuKwM6tKUY7JmNIdZtvZLWz3_rUWrMR1Rs/s320/2012-11-16_13-42-43_457.jpg" width="320" /></a></div>
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Here's what the robot looked like without all of its hardware. It's kind of cute!<br />
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The robot easily held onto the ceiling as 20% throttle when we added some cardboard skirts to create essentially a fancy suction cup. Our dorm room had some silly Christmas decorations because we like to stick things to our ceiling.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsPQ4MaT097PDb5XpsxHldnjGAqPaCORe3LrUXgSLkmuekOPB1GpBKlI0LnP6stJLGrol57_XsKJPv5nohskHAGbcMwFyfcT-QtABDHLhT1KtEQnIbK7ofU1fqyuCOeBqG2WZ4LeqcT80/s1600/2012-12-02_19-39-56_651.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsPQ4MaT097PDb5XpsxHldnjGAqPaCORe3LrUXgSLkmuekOPB1GpBKlI0LnP6stJLGrol57_XsKJPv5nohskHAGbcMwFyfcT-QtABDHLhT1KtEQnIbK7ofU1fqyuCOeBqG2WZ4LeqcT80/s320/2012-12-02_19-39-56_651.jpg" width="320" /></a></div>
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We also made a pretty sweet dorm Christmas photo without the need for Photoshop!<br />
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The robot ended up "blowing away" the competition. One thing that came up during the project descriptions was how many amps the project drew. It started with one project drawing 2 amps. The next project drew 6 amps and had to have a very interesting power supply to use the small voltage regulators. Then ours came up which could draw 60 amps! This little robot was fun to drive around and led us to victory!<br />
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PROS<br />
-Fun to play with<br />
-Loud (it sounds menacing)<br />
-Cheap<br />
-Quick to make<br />
-Won the Awesome Things Competition<br />
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CONS<br />
-Loud (We got noise complaints when testing it at 3am)<br />
-Under-powered drivetrain (it's neither fast nor able to push stuff)<br />
-Cludgey electronics (we had to be careful not to short wires or have it fall apart)<br />
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Overall this robot was awesome... you might even say the most awesome. At some point if I have free time I'll rebuild it with proper electronics and a nice drivetrain so it moves better.JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0tag:blogger.com,1999:blog-4585776524802028435.post-15129888918245465922012-10-22T17:40:00.000-07:002012-10-22T17:40:36.281-07:00Guitar and Desk Lamp UpdatesI haven't concentrated on either the guitar or desk lamp. I really only get time to work on Friday nights after dinner until the school shop closes. The other days are reserved for homework or club activities (New combat robot club at school). The guitar only has the pickup cover plate and the potentiometer knobs left. The only new parts for the lamp are half of the base and the electronics.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFMfA54OaRTvfkRD30N07Z_Za5OHE9F8p-DJ46zHcdRPodAJMPuUtfDCVpB9PvZaC5gmVNvBfYlHja9aN2yaVqqLmpxuC8rTmydDTTOqi9mwhFqLTXVCqbcFLx5cvqoeiVym9pKdBHWUg/s1600/Guitar+concept+1.6+assembly+render+5.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="225" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFMfA54OaRTvfkRD30N07Z_Za5OHE9F8p-DJ46zHcdRPodAJMPuUtfDCVpB9PvZaC5gmVNvBfYlHja9aN2yaVqqLmpxuC8rTmydDTTOqi9mwhFqLTXVCqbcFLx5cvqoeiVym9pKdBHWUg/s400/Guitar+concept+1.6+assembly+render+5.JPG" width="400" /></a></div>
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I had to redesign the side plates of the guitar... I was looking over the CAD again and realized the center of gravity was over the fret board. This is very different from a normal guitar because the body is usually heavier than the neck. I modified the top plate to reach out far enough to ensure the center of gravity is between the two strap positions. I know its still not centered between the strap connections, so it will still want to rotate down, but I should be able to play it with the current design. After playing the guitar for the past few months I noticed the best way to play it because of its "unique" center of gravity placement was to place the point at the bottom of the guitar under one leg. That's why the top doesn't have a leg thing sticking out.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_s6UUKOD9lXAO8Y-qMj_lgJQL5NiWIFDqWjq9-BgDMWt3r3MNvUfjkDZsiqNGuYAQqig9y821puKDO9jlNGuu78Lfo1HfJlnPcCaCCEVVDVcEbNg_OQazKjkMEIgv7-0KSxLp7PZ12cM/s1600/2012-10-12_23-13-21_678.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_s6UUKOD9lXAO8Y-qMj_lgJQL5NiWIFDqWjq9-BgDMWt3r3MNvUfjkDZsiqNGuYAQqig9y821puKDO9jlNGuu78Lfo1HfJlnPcCaCCEVVDVcEbNg_OQazKjkMEIgv7-0KSxLp7PZ12cM/s400/2012-10-12_23-13-21_678.jpg" width="400" /></a></div>
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Machining the side plates was fairly straight forward. I didn't quite have the right clamps, so I used washers, which worked great. Some needed support on their opposite sides, so I stacked a few screwdriver bits to be 1/2" tall. The parts came out perfectly and the clamps didn't slip.<br />
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Putting the holes in the edges of side plates was a little more difficult. I had to align them in the vises. The hole positions aren't very accurate relative to the part, but they're perfect relative to each other. The only tolerance that really mattered was the spacing on the holes, not their absolute locations.<br />
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I still haven't done the pickup cover plate, so I still need to use blue tape to hold it in. I finally switched to the chrome plated Gibson pickups. They sound better than the used beaten-up one I was temporarily using. I also need to polish the side plates, but that's fairly time consuming, so I'll put that off for a while.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgo5Vl9yDsERPTIyKlZN0AlsG6lyMzEQ0a00FlcQKxzzTs_X4M8VZWQRJ9WTgspFpu8VgKaW9ly9zL8To10yEpAXt3gwKca3kacwsixY0d9SJI_l2bGInqIm7DBzGZsWMOprwy-07vJ8FM/s1600/2012-10-22_17-01-53_436.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgo5Vl9yDsERPTIyKlZN0AlsG6lyMzEQ0a00FlcQKxzzTs_X4M8VZWQRJ9WTgspFpu8VgKaW9ly9zL8To10yEpAXt3gwKca3kacwsixY0d9SJI_l2bGInqIm7DBzGZsWMOprwy-07vJ8FM/s400/2012-10-22_17-01-53_436.jpg" width="300" /></a></div>
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I also finished the body, so the guitar now has a legitimate jack. Its nice not having to zip-tie and solder the cable to the pickup now. The volume potentiometers are mounted, but I haven't wired them in yet. I still need to machine their shafts down for the knobs to fit properly.<br />
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The guitar is getting close to matching up with its render. I added a wooden thing to the render so it wasn't laying in a strange orientation. I will not be making that part.</div>
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As for the lamp, I got to try out my new indexable end mill. The original block was 20 lbs of aluminum. I think it was 6061, but I'm not really sure because I bought it from a metal recycling place. It was less than 1/4 the price of a new piece, so I figured it was worth the risk on a part that's essentially an aesthetically pleasing paper weight. I brought the part down to around 12 pounds. If I had a coolant system to clear the chips I'm sure I could have cut alot faster. My cuts were 1/4" deep and 1" wide. The machine was pretty much silent while slotting. I was really impressed with the endmill's quality.</div>
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For size reference the base is 8" in diameter and the endmill is 1" in diameter. I was glad I thought ahead and assumed the endmill's edges weren't perfectly square. It left ridges as I cut deeper, so I was forced to surface the outside with a 6 flute HSS endmill. I've heard its a common problem with these types of endmills, but It's also possible it was my fault for buying the inserts from a different supplier than where I purchased the holder. I think I understand the carbide insert codes that determine their dimensions and tolerances. I may buy the more expensive aluminum specific inserts if I have another large amount of material to remove.<br />
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The hardest part about machining this was cleaning up the chips. 8 lbs of chips thrown all over the mill and floor is painful to clean up. That's the biggest reason I've put off machining the top side. I'm probably going to finish the guitar before the lamp because it is a lot closer to completion, but I might do the lamp first. It all depends on what machines are available for use.</div>
<br />JBhttp://www.blogger.com/profile/12777804612856896625noreply@blogger.com0