Milling machine motor temperature

[ChrisBoon]

Hi

I had my milling machine motor overheated to the extent that the fan totally melted (my own fault I think). It is a new machine that I have net even used for 6 hours. It was in storage for 4 months since I bought it. The shop whom I bought it from will not repair/replace it under warranty as the motor is only under warranty for 3 months.
OK so it is what it is. The running capacitor leaked out a lot of wax. I tested the capacitor, and it seems OK, but I will replace this. The motor seems to be running fine but is heating up. After working for about half an hour, at normal milling conditions, I can only hold my hand on the motor for a few seconds because of the heat. I have replaced the fan. Unfortunately, I do not know how warm the motor ran before. How hot can the motor get before it burns out? I will replace the motor but would first like to spend my money on some much-needed tools. I just bought a DRO for the mill. I will buy a higher temperature thermometer if I have to.
Is it wise to use the machine in the meantime? Well, if it packs up so be it. Maybe it will keep on running for a long time.
Any advice will be appreciated.
Thank You
Chris

 

[den-den]

Is this a capacitor start, capacitor run motor? If a capacitor has leaked, it is almost certainly bad. A bad run capacitor would make the motor overheat. Some motors run fairly hot anyway, depends on the insulation class how hot it can run without failure. Do you have an amp meter to check how much current it is pulling? If so compare that to the motor nameplate. Check the insulation class rating also.

 

[ChrisBoon]

Is this a capacitor start, capacitor run motor? If a capacitor has leaked, it is almost certainly bad. A bad run capacitor would make the motor overheat. Some motors run fairly hot anyway, depends on the insulation class how hot it can run without failure. Do you have an amp meter to check how much current it is pulling? If so compare that to the motor nameplate. Check the insulation class rating also.

It is a dual capacitor motor. I have several multimeters, but I think none them can measure above 10 AMPS. I will check in the morning.
Thank for the feedback.

 

[markba633csi]

Is the voltage there 220 volts AC? Is the motor wired correctly for the voltage? Motors shouldn't run so hot you can't touch them. Running on the wrong voltage can cause overheating. Definitely replace the run capacitor; it has the smaller microfarad value of the two.
If the capacitors are OK then another possibility is a partial short in the windings which unfortunately isn't a fixable issue- new motor time

Very seldom a problem is encountered with the centrifugal start switch inside the motor being stuck closed or bypassed by incorrect wiring; this would also cause overheating but usually would fail the start capacitor in a short period of time as well-

Post a picture of the motor terminal connections if you are not sure of the hookup

 

[Huub Buis]

Your motor fan needs a minimum RPM to work. When running at low RPM, select the "low gear" option (if your milling machine has one) to increase motor RPM.