acceptable motor temperatures after upgrade?

[alan025 0]

I've upgraded my X and Y stepper motors to the larger ones sold by Ultimachine. Printing appears to be smoother when there are rough spots in the blue tape or the previous print layer . However, I'm a little concerned about the motor temperatures during longer prints. Using a thermocouple on my multimeter, the bottom case of the motors seem to stabilize at 120 F (49 C). Is that too hot? The extruder motor (original part from June 2011) only runs about 90 F (33 C). (All temperatures measured when ambient temperature was 68 F, 20 C).

If 120 F is too hot, any suggestions on how to reduce the temperature? I can think of two that could be quickly done - lubricate the x/y rods and dial down the stepper currents (I think that's what it's called). I have been lubricating the x/y rods with a white lithium grease, but a thinner machine oil may be more appropriate, I don't know. Any thoughts?

Finally, if anyone can suggest a good reference for learning the in's and out's of stepper motors (voltage, current, torque, speed, temperature) I would be eternally grateful. Old dog, new tricks, and all that!

[IRobertI 521]

I wouldn't worry about the heat. Steppers do tend to get a bit hot but IIRC it's perfectly safe to run them up to about 80C or so. It might've even been higher than that but I'm not quite sure, someone else will have to verify. If you're still worried about it you could attach a few small heatsinks to it to help dissipate the heat or you could try turning down the drive current.

[cyclone 0]

You can reduce the heat by turning down the pots on the x and y stepper drivers.

I can't seem to locate the page on the wiki but turning them counter clockwise turns down the voltage, clockwise turns up the voltage. You want them as low as works without skipping steps.

-b