Carduino V2 Pinion with Set Screw

thingiverse

Because the pinion gear in the original Carduino design is just a friction-fit, it wears out fairly quickly as the motor heats up and spins inside the gear. To make it last longer, I decided to poke a hole between the gear threads for a set screw, which works in combination with filing a flat spot on the motor shaft. I am using an [M4 x 6mm set screw found at Home Depot](https://www.homedepot.com/p/Everbilt-M4-0-7-x-6-mm-Plain-Steel-Metric-Socket-Set-Screw-2-Piece-per-Pack-813778/204275887), but I'm including an STL for a 3mm set screw as well. The set screw will cut its own threads as it goes in, just be careful not to overtighten. To file a flat spot on the motor shaft, you will need a small flat file. To prevent the tiny metal filings from getting sucked in by the motor magnets, put the motor in plastic wrap or a baggie, and poke a hole through the plastic for the shaft. Put the bagged motor in a vise, and carefully file on one side until you have a decent flat spot down to about 1/2 to 2/3 of the length of the exposed shaft, then remove from the vise and carefully remove the plastic.