I've built some fast pinewood derby cars in the past but this year was just about looking good. I've always loved the way those lowriders bounce and thought it would be cool to make a derby car do that. Here's my version. A few more pictures and build details after the jump.
The body is a regular derby block with side panels added for the wheel wells.
I cut the side panels separately and then glued them on before sculpting the top.
The mechanism uses four tiny servo motors:
mounted in a 3d printed frame.
The servos are connected to the pinewood derby wheels and axles with a custom servo horn that I designed in FreeCAD.
The servos are driven with an Ardweeny
The ardweeny doesn't have any voltage control onboard so a friend showed me how to use an LM317 voltage regulator to step a 9V battery down to 5V.
The whole thing goes together like this. It's a pretty tight fit and you can see some white areas that I had to trip with a utility knife because the wheels were still rubbing.