Stepper Calibration Dial ( 28BYJ-48 )

A quick and dirty snap-on calibration meter for the cheap 28BYJ-48 stepper motors. It seems that different batches of these motors have slightly different final gear ratios. Reading online and in my experience, they use anywhere from 4075 - 4100 steps per full rotation of the axle. (in half-step mode, 360 degrees.)

This disc has indexes every 10 degrees, and secondary marks at 45 degree increments.

There is a little bit of lash in the gearbox, so these motors are not perfect, but by running three motors through 20 full rotations simultaneously, I was able to get a very accurate calibration for my lot of motors. (4096 steps in my case.) I also ran each motor through a series of back and forth movements to test for skipped steps, etc... all returning to zero position at the end. (Stepper Calibration Dance Video)