Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Old April 28th 19, 08:18 PM posted to rec.crafts.metalworking
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Default Bench grinder motor stalling

replying to Wild Bill, Confused wrote:
Hi I have a bench grinder that I converted for polishing. Recently the thing
has lost power when I push against the polishing mop and I can even stop it
rotating if I grab hold, can anyone loll me what’s up. I’ve opened it up
and had a look, no debris or broken parts, no bearing wobble. Is it the
capacitor or is it toast?

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Old April 30th 19, 03:57 AM posted to rec.crafts.metalworking
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Default Bench grinder motor stalling

On 2019-04-28, Confused wrote:
replying to Wild Bill, Confused wrote:
Hi I have a bench grinder that I converted for polishing. Recently the thing
has lost power when I push against the polishing mop and I can even stop it
rotating if I grab hold, can anyone loll me what’s up. I’ve opened it up
and had a look, no debris or broken parts, no bearing wobble. Is it the
capacitor or is it toast?


Almost certainly the capacitor. And they are cheap, so get a
replacement and swap it in.

You probably cooked the capacitor when pushing too hard against
the mop and stalling it, which results in the start centrifugal switch
closing, and applying power to the capacitor for too long. They can
only take a very short application of the AC which drives the motor.

Get several spare caps, as you will probably be killing more of
them in this application.

Better if you have a three-phase motor and a VFD to drive it.
That can take the extra load a lot better than a cap-start motor.

Good Luck,
DoN.

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Old May 1st 19, 07:01 AM posted to rec.crafts.metalworking
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Default Bench grinder motor stalling

On Sun, 28 Apr 2019 19:18:02 GMT, Confused
wrote:

replying to Wild Bill, Confused wrote:
Hi I have a bench grinder that I converted for polishing. Recently the thing
has lost power when I push against the polishing mop and I can even stop it
rotating if I grab hold, can anyone loll me what’s up. I’ve opened it up
and had a look, no debris or broken parts, no bearing wobble. Is it the
capacitor or is it toast?


It could..could be the capacitor..which typically is only used for
starting if there is a single cap. Clean up the contacts and check the
movement of your centrifugal starting switch..which it may..may have.

If both are ok..you have a bad winding.

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