Stepper motor tune-up aid

thingiverse

I encountered an issue with 3DBenchy. The cabin walls developed diagonal stripes with 0.1 & 0.05 mm accuracy. This phenomenon is known as 'Zebra stripes' or 'Moire'. The problem arises because our stepper motors aren't rotating full steps, but instead electronically create fractions of the steps (microsteps), such as 1/16. These microsteps are not accurate, especially near the motor's full step area, and their accuracy depends on the current feeding into the motor. This phenomenon is visible when the motor needs to make precise movements. The surface at a low angle towards the axis makes these steps noticeable. I created a test piece to demonstrate this issue. The X-axis (ends) and Y-axis (middle two) surfaces are 5 and 10 degrees off from the ideal angles. During printing, I adjusted the motor drivers' current to find the optimal settings for both axes. On the left is my original setting, while on the right is the optimized result. When the current goes too low or high, steps are missed - resulting in gaps in the picture. I strongly advise exercising caution when handling live electronics! Use a non-conductive screwdriver when adjusting trimmers (or have a very steady hand). Also, avoid static electricity by not wearing synthetic clothing and earth yourself before working. The Z-axis shouldn't be an issue. For instance, M8 thread has 1.25 mm progress per rotation (pitch), while the Nima17 motor has 200 steps per rotation - resulting in 0.2 layer height with 32 full steps or 0.5 giving 8 steps. These are good and don't involve microstepping. However, if you want to use a 1/100 inch layer height, you'll get a rotation of 6 1/4 steps, which might cause problems.