So I have a motion control system with a P70360, UMI 7772, PXI 7332, and a NEMA 23 stepper motor with 380 oz-in. The purpose of the set up is to rotate horizontally a testing fixture and hold it in position (slowly). Previously the set up was using a motor with 180 oz-in but it was decided that it wasn't enough torque seeing as it wasn't able to fully rotate the fixture, also using a step resolution of 18000, current reduction is disabled, multistepping is enabled, dynamic smoothing is minimal, and load-inertia ratio is set to 0-1.
When the 380oz-in motor was plugged in it was still unable to rotate the platform completely but it wasn't even able to rotate it as far as the 180 oz-in which leads me to believe it was outputting less torque than it should have been. The only reasoning I could think of for this was that there was an issue with the settings somehow where it was limiting the power being fed into the motor for whatever reason. So I walked through the manual (http://www.ni.com/pdf/manuals/372324d.pdf) and it still wasn't giving enough torque.
I also read that decreasing the step size would increase the torque so I reduced it to 200 and it started making a grinding noise, which made everyone in the lab stare at me and start laughing... I immediately hit the kill motor button (I've been controlling it using NI MAX).
So far I can't seem to find anything that mentions the motor making a grinding noise or not pulling enough torque while using the P70360 so here I am asking the community. Why is the motor making the grinding noise (which also seems to become less the higher the step resolution is) and why isn't the motor putting out more torque?
Also of note, I'm an electrical engineer, meaning my understanding of mechanical terms is limited to the basics.
Thanks for any help you can give.