How Strict is the Max Vsupply Calculation for Steppers?

[Neale]

One possible reason for different temperatures for the two motors on your Y axis is whether or not you have "half current when stationary" selected on both. A lot of stepper drivers have this option available - it cuts motor current to half normal value if the motor is just holding position and not moving. I'm only guessing here - I would expect the DIP switches on both Y drivers to be set identically.

[routercnc]

My thoughts would be to unplug both Y motors from the drivers (power off!) and do a simple check of the resistance through the pairs of windings in both motors. They should all be about the same, around a few ohms.

If you are de-rating one of the steppers on a dual stepper axis just go easy on the feeds to avoid stalling one out before the other (assuming they are just slaved in software)

[mattnedgus]

I would expect the DIP switches on both Y drivers to be set identically.

Hi Neale, yeah all DIP switches are the same.

My thoughts would be to unplug both Y motors from the drivers (power off!) and do a simple check of the resistance through the pairs of windings in both motors. They should all be about the same, around a few ohms.

If you are de-rating one of the steppers on a dual stepper axis just go easy on the feeds to avoid stalling one out before the other (assuming they are just slaved in software)

I may check the resistances in the future but once the current setting was lowered again the difference in temperature wasn’t anywhere near as bad - maybe 5-7degreesC.

I’m not sure I understand what you mean by de-rating one of the steppers? Both are set the same to half step and a lower current (I think this might be what you mean by de-rating?) to manage the heating. I spoke to Gary at Zapp who set me straight on matching/setting to the the Peak current on the motor driver to the current rating of the motor but still remain confused, especially when I’ve read Leadshines advice is to match/set to the RMS column.

I’ve run the motors fine by setting the motor drivers Peak current value to match the specified motor current for a few years but I’d hoped to better understand why it’s done this way.

All I can figure is that I can either have higher voltages for more torque at faster speeds, but I have to set a lower current (match the motor current to the Peak value on the driver) to manage the heating OR I can set the drivers to match the RMS value to the motors rating and have a lower voltage, again to manage the heating - I ‘suppose’ then I’d get higher lower speed torque, but lower top speeds/top-end torque due to the lower (thus slower) voltage changes?

I could do with a good reference text!