Heat Issues

[racer]

I just replaced the router on my PR due to heat issues. I have also noticed some heat build-up at the motors and on the control box. There have not been any noticeable differences in ambient temperature due to weather change. The PR is about 8 months old and used for proto typing only with weekends being the days of most use. Any ideas out there? Also; should the motors be bolted somewhat tight or be able to swing freely. thanks

[richards]

Stepper motors can run hot. I don't know the model number for the motors that you have, but I'm assuming that they are the "Oriental" brand. The 29X series can have a heat rise of 170+ degrees (refer to the Oriental motor web site).

On my Alpha, I have the motors bolted loose enough that they can easily be held in contact with the rack by the Shopbot supplied springs.

[gerald_d]

Stepper motors get the hottest when they are holding a position - ie. standing still, but switched on. As Mike said, they are allowed to get very hot, hotter than the outside of a metal kettle with boiling water inside. But I would get nervous if I couldn't hold my hand on them for 5 seconds.

The control box should be a lot cooler than the motors - I don't know the spec. However, "feeling" a temperature and then deciding whether something is cold, cool, okay, warm, hot is very subjective. Especially when we have thermometers that we could leave inside the control box for 30 minutes and then take an accurate reading.

How tight must the bolts be? I would suggest that they are tight enough so that the motors don't swing under own weight when the springs are disconnected, but loose enough to push them into the rack by hand.