Jointer motor hums but won't turn

[Tom Porter]

I was running my jointer the other day. It was running fine for a while. I turned it off for a few minutes and when I turned it back on, the motor hummed but wouldn't turn. There is a reset button on the top of the motor but it doesn't seem to have been tripped (at least pushing the button doesn't do anything). The jointer is an AMT but the motor is a GE. I think I remember the guy I bought it from saying he had replaced the motor. In fact, he had ordered the motor and for some reason, he had received two. When he sold me the jointer, he gave me the second as well. So if the one in there has gone bad, I can swap it out with the other. But I'd like to avoid that if I can. I'm not very experienced with electrical issues, so I thought I'd ask if anyone has any idea if there is anything I could try before replacing the motor.

Cheers.

[Al Currano]

If it is a single phase motor it uses a capacitor to start the motor. If the capacitor is bad the motor won't start. Sounds like that could be your problem.

The capacitor is located inside a small enclosure that forms a hump on the side of the motor housing. If the capacitor case looks burned or swollen it is probably bad. If not, it may still be bad. You can check the capacitor with an ohmmeter for shorts and open or damaged plates. Google "motor start capacitor test" to find out how.

This is an easy fix, and capacitors are readily available, but make sure to replace it with the same size capacitor (usually printed on the capacitor case as some number of microfarads, a.k.a. uf or mf. This is an easy fix, though you have to know how to solder correctly.

[david brum]

The first thing I would check is the centrifugal switch on the motor shaft. You'll have to remove the fan cover from the motor and check to see if the collar that holds the switch onto the spindle has slipped. I've had this happen on jointers and lathes (both Asian). Easy fix.

The second thing I'd check is the start capacitor. It's under one of the bumps on the outside of the motor. It will probably have a popped cap with liquid gunk oozing out if it's failed. If it isn't either one, it might be easier to pop on the second motor.

I attached vague representations of both components

Oops, just saw that Al posted the same comment about the capacitor.

[Jerry Wright]

Centrifugal switches often get clogged with chips. Remove end caps and blow everything out.

[Carl Beckett]

First thing I would check is to be sure everything turns freely by hand...... Not bound up bearing or pulley or such

Then the switch. Then the cap.

[Steve Rost]

Wow, Every thread above is spot on. Responses don't get better than this.

[glenn bradley]

These boys are good ;-) If it is a cap and you don't have a local source (like I didn't), these guys (http://www.temcoindustrialpower.com/)are very helpful and reasonably priced.

[Lynn Floyd]

I just replaced the capacitor on a metal lathe. A setscrew on the centrifugal switch had come loose. This caused the capcitor to go, or at least that's what the guys at the rewind shop said. Make sure this thing turns as the motor shaft turns. Capacitors cost about $7. They usually attach to the 2 motor wires with stab locks or screws but may require solder. The motor should run with a hand start but I wouldn't do much of this as you may burn the windings. Three phase does not have this problem.

[Bill Bukovec]

Give it a smack with a mallet when it is humming.

This may cause the centrifugal switch to close, then start the motor.

If it starts, you know the switch is the problem.

I need to smack mine every once in a while.

Bill

[Tom Porter]

Thanks for all the advice, especially the mallet idea. That one is about my skill level. But failing that, I'll try the other ideas as well.

[Pat Barry]

If it was running and then you turned it off, and it was not overheated, then I would definitely suspect there is something jamming it up. Unplug it, and manually rotate the cutter, forward and back. Is it free and clear?

[Anthony Diodati]

well what was it?
Its nice to follow up!