Inconsistent step size with NEMA 17 motor and TIC T825

I’m using this stepper motor ( Stepper Motor: Bipolar, 200 Steps/Rev, 42×38mm, 2.8V, 1.7 A/Phase, part #2267) along with a TIC T825 over USB to achieve very fine control of focus on a telescope. When set to full step, the motor makes consistent steps all the way around. When set to 1/2 step, the motor alternates making one large step and one half step. When set to 1/4 step, I get one large step, three small steps, then another large step. This pattern continues all the way up to 1/32 step, where I get one large step followed by 31 small steps, etc. I’d like to be able to use 1/8 or 1/16 step for very fine focus movements, but the large step that occurs throws the focus way off. Is there any way to get consistent small steps without the large one repeating each cycle?
Thanks so much!


What you described sounds like normal microstepping behavior. Unfortunately, while microstepping is great for smoothing out motion, it is not typically very accurate or precise. Achieving very precise position control with a stepper motor usually requires using an integrated high-resolution encoder or a high reduction gearbox that has no backlash, or both.


Hello Brandon,
Thanks for the reply. This is good to know. I have a number of gears that I can use with full step increments to get precise control since each full step seems to be the same size throughout the range of travel.
Much appreciated,