# Lathe motor problem



## Packhorse (Mar 27, 2010)

I am having an issue with my 240v single phase 1hp motor for my lathe.

The other day it was making arcing noises when I started it up.
Yesterday the arcing noise had gone but when I turn the motor on it would go very slow and I would have to give the chuck a spin by hand to get the motor running at normal speed.

Anyone got a clue what the problem is?

I am thinking it maybe the capacitors or it may be the bushes but I dont really have a clue. Im a 12v DC kind of guy.


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## gadget_lover (Mar 27, 2010)

It sure sounds like the capacitor. The fact that it runs normally once you get it moving is the clue... It could also be the starter circuit cut-out switch that has gone bad. I'd supect the capacitor first.

http://en.wikipedia.org/wiki/Induction_motor#Single_Phase

Daniel


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## precisionworks (Mar 27, 2010)

No brushes on an AC induction motor, so it's either the starting cap or the centrifugal switch. The cap is easy to test & replace but the switch is not.


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## 65535 (Mar 27, 2010)

If the cap is bad I bet you anything it has leaked, if that's the case they are quite cheap. If it's the switch new motor time.


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## Torque1st (Mar 28, 2010)

Hope for the best. Some digital meters have a capacitance measurement function. Remove the capacitor under the "bump" on the motor and check for the value written on the side. Test the capacitor with the proper meter. If the value is more than 20% off from the one marked, replace the capacitor. They are available from some electrical supply houses and motor repair businesses.


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## cmacclel (Mar 28, 2010)

I have gone through 3 start caps on my old HF 3 in 1 machine in the past 5 years. It sounds exactly like a start cap to me. I now have 2 spare's lying around. My motors have 2 each.

Mac


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## Packhorse (Mar 28, 2010)

Thanks guys.
I have 3 meters one being a Fluke scope meter and none have a capacitance meter.
I guess I will just try swapping out the parts which should be easy enough as they are external.


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## Torque1st (Mar 28, 2010)

I have two digital meters (not Fluke) and both of them have capacitance ranges. They even agree with each other. No scope-meter, but I do have an O-scope. Sounds like you need a fourth meter.


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## Packhorse (Mar 29, 2010)

Any excuse for a new toy...err tool.


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