Hi Tom,
I have just swapped my stepper motors to some with a lower current requirement as the original ones were causing thermal shutdown despite having large heatsinks attached.
The new ones have the following specs:
Manufacturer Part Number 17HM15-0904S
Motor Type Bipolar Stepper
Step Angle 0.9°
Holding Torque 36Ncm(50oz.in)
Rated Current/phase 0.9A
Phase Resistance 6.0ohms
Recommended Voltage 12-24V
Inductance 12.0mH±20%(1KHz)
I have set the current limit by measuring vref - set this to .42 volts, so the motors should be limited to a current within their specs. The driver chips barely get warm, however the motors get very warm - not too hot to touch, but about "cup of coffee" warm.... Is this OK? Don't want to damage the motors. Did notice that limiting the current to below the motors specs caused microstepping to become less smooth..
cheers
Gary