N20 Motor Quick Test Stand

thingiverse

This stand is designed for testing the common N20 gearmotors found on eBay and AliExpress. Multiple gear ratios can make these motors hard to tell apart, but this stand makes it easy to go through them all and measure each one with a non-contact tachometer like the one shown: https://www.amazon.com/Digital-Photo-Laser-Tachometer-Contact/dp/B001N4QY66/. You'll need two M3x12mm socket cap hex screws, two M3 nuts, two alligator clips and a 9v battery (optional). The nuts fit inside the stand and the screws go in from underneath. Attach the alligator clips to the screw heads, making sure the nuts are at even height. To get the nuts in place, try dropping them into position and using an N20 motor to hold them steady while you tighten the screws. The test wheel part is optional. The tachometer will measure off the flat of the motor shaft, but if you need to, you can print a test wheel and stick the reflective tape sticker from your tachometer onto it for more accurate measurements. A 9v battery is also optional - using a 12v power supply instead makes things easier, especially with motors that require higher voltage like mine do.