After making Thing-O-Fun's functional differential gear system and playing with it for a while I realized that this thing just had to be motorized. I had a Solarbotics GM9 gear motor lying around and it was a perfect fit. All that was needed was a modified input shaft to match up with the shaft on the gear motor and a base to hold the batteries and power switch.
I included the scad file so that you can easily change the switch opening to fit your switch.
Watch it in motion at http://youtu.be/bFceF0CeGFk
- Make the functional differential gear system (you can skip the shaft and one of the handles, as they are not needed with the motorized version.
- Print the base and the input shaft.
- Put the Input Shaft on the Input Pinion and assemble the gear system.
- Line up the GM9 shaft with the Input Shaft and hole it in place.
- Solder wires ~3 inches long onto the GM9 terminals.
- Drill two holes about 2.8mm into the stand, using the holes in the GM9 body as a guide. Use the M3x22 screws to mount the motor.
- Solvent weld the gear system to the base.
- Glue in the battery holder, install the switch, and hook it all up.