I have not tried setting as a spindle yet. i think i can get that working. I did try as a linear axis and that made no difference. I reset the eprom to factory settings and started over. That didn't make any difference either. Did a little more tuning and it is more responsive now but still only goes in one direction from mach3 even though i can see the dir. pin change from 5v to low. From Ultraware, it will do everything it is supposed to, for, rev, and rpm. This just keeps coming back to poor pulse stream from mach3. I finally got the oscilloscope function to work. Yeah the pulses don't resemble a square wave at all. Maybe you have good luck with these because of the smooth stepper outputting cleaner pulses?