How Strict is the Max Vsupply Calculation for Steppers?

[mattnedgus]

Different motor manufactures give the maximum temperature as either 70 or 80 C

Best advice is generally to start with the driver current setting set to the nominal motor current as per spec sheet, then check the motor temperature after it has been running for a little while. If it's a bit too hot to hold for any length of time, drop the current setting by one step. If it's much cooler than that, increase the motor current setting. That equates to a motor surface temperature of about 60degC at which point the internal motor temp shouldn't be too high.

Thanks for your replies. Ive just gotten around to cutting today after being away.

It turns out I have been running the motors 2 settings below the desired current setting for the last (nearly) 4 years!

I’ve corrected the setting today and I’m getting 70-75degC surface temp on one Y motor and 90-95degC on the other, after 30 minutes running in 27-29degC ambient. I’ll measure the voltage from the two psu’s tomorrow to see if that’s causing the difference, otherwise I suspect something is wrong with one of the motors. The X motor was also about 70-75degC and Z was so low I didn’t bother measuring much. I’ll have to drop the current a level (at least!), as Neale suggests, to be comfortable with the motor that is running extra hot for now, until I can swap it or figure out it’s cause.

Any ideas what else might cause one motor to run so much hotter than another using the same drives and psu voltages? The motors are labelled the same, from the same source.