I am trying to run this stepper motor (XY42STH34-0354A), but I am encountering two odd issues with its performance: slowing of the motor in 1/32 microstep mode, and a "soft cap" of the RPM where the speed of the motor barely changes despite increasing the RPM parameter.
Here are the motor specs:
Rated voltage: 12V
Holding Torque: 20N-cm
I'm currently using a DRV8825 stepper motor driver with the motor using a 30V supply and am controlling it with an Arduino Mega, using this stepper library I found online. I believe that all my wiring is correct, and I've properly set the current limit on the DRV8825 to the rated current limit of 0.35A following the instructions on the Polulu website. The motor runs smoothly within a certain RPM range at all microstep settings.
When I use the 1/32 microstep mode of the DRV8825, it is noticably slower (~20%) than that of the other modes (1/16, 1/8, 1/4, 1/2, 1) for the same RPM setting, but other than that, works great (smooth, no rattling or other odd behavior). I think the motor may speed up slightly as the microstepping setting gets more coarse (towards fullstepping), but it's small enough that I really can't tell.
The second thing I noticed was that despite increasing the RPM setting, my motor hits a maximum of about 4-5rps. There is a range of RPM settings (300-900RPM) in which changing the RPM value won't result in any noticable difference in the speed of the motor, which is what I refer to when I say "soft cap". Exceeding that limit causes the motor to jitter.
Could anyone help me understand why the motors are behaving this way? Looking at some other NEMA17 stepper motors online, I see that they have a lot lower voltage ratings (2-3V) but much higher current/phase (1-2A). Could it be that the driver I chose isn't correct for my stepper's specs, or that the lower-voltage higher current types run faster or better? Thank you.