I'm having an issue with my stepper motor, while I am aware they should make a noise that is dependent on the current and speed of the stepping, the issue I'm having is the noise is changing. For example, if I tell it to take 5000 micro steps (1/16), 1 every 700 micro seconds, perhaps after 500 steps, the frequency of the sound changes for a brief period (perhaps 1/4 second) then returns to what it was.
The typical sound is a fairly high pitched whine, the "different" sound is a slightly lower pitched sound.
The reason I ask is that I am having accuracy issues with this stepper, it is attached to an axis and if I move it 5000 steps forward, then 5000 steps backward, in some cases (not all) it is not in precisely the same position.
The power supply used is just a regular computer PSU (I had one spare) and the connector is providing 12V at upto 40 amps, the manual on the PSU states that the current is regulated to within 5% and the volts may fluctuate by upto 120mv, could this fluctuation be causing the issue? If so, how can I rectify this?
I'm working with this stepper motor: https://www.sparkfun.com/products/13656 and this driver: http://www.robotshop.com/ca/en/pololu-single-bipolar-stepper-motor-driver.html