Saturday, December 15, 2012

Guitar Finished

The 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.

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.

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.

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.

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.

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.

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.

Here's my list of pros and cons for the final product.

-Sounds better than my other guitars. (probably the nice pickups, but it might be the solid aluminum construction)
-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)
-The neck feels really nice. The 3D profile machined ridges make a really neat texture.

-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.

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.

Sunday, December 2, 2012

New Project (finished too) - "Anti-Gravity" Robot

We 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.

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?

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.

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.

Here's what the robot looked like without all of its hardware. It's kind of cute!

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.

We also made a pretty sweet dorm Christmas photo without the need for Photoshop!

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!

-Fun to play with
-Loud (it sounds menacing)
-Quick to make
-Won the Awesome Things Competition

-Loud (We got noise complaints when testing it at 3am)
-Under-powered drivetrain (it's neither fast nor able to push stuff)
-Cludgey electronics (we had to be careful not to short wires or have it fall apart)

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.