Author Topic: Mill motor question  (Read 863 times)

Offline awake

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Re: Mill motor question
« Reply #15 on: January 11, 2020, 05:04:39 PM »
One of your pictures shows an internal capacitor - or was that the picture from the internet that did not match your motor? There is a capacitor on the side, I take it; does it have the value indicated (μF)?

Describe the symptoms again: does it never really start (just crawl along), or does it start but not come up to full speed? Lots of induction motors use a single start capacitor which comes out of the circuit when the centrifugal switch releases. If the cap is completely bad, it likely wouldn't start; it would just hum. Same is true if the centrifugal switch did not close. However, if the centrifugal switch doesn't open when the motor starts to spin, I'm not sure what the symptoms would be (definitely overheating as mentioned above) but in any case it wouldn't run right. I'd take a close look at the centrifugal switch; I'd also look at finding a similar start cap and trying it in the circuit - if you know anyone who works in HVAC, you may be able to browse the scrap bin and have your pick of both run and start caps.
Andy

Offline galland

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Re: Mill motor question
« Reply #16 on: January 11, 2020, 06:06:27 PM »
The photo showing the internal capacitor and switch were just from the internet and is what I expected to find inside but mine has nothing but the armature with a bearing at each end. The external cap is a 20uf. I probably should buy one just to make sure that's not the problem. I stated I was making a light cut and the spindle slowed from 800 rpm to a crawl and I shut it down immediately and waited a couple hours and came back and tried it and the motor again crawled again at maybe 60 rpm. Motor spins free with no load and gear box is fine.   Gary

Offline Alyn Foundry

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Re: Mill motor question
« Reply #17 on: January 11, 2020, 06:33:53 PM »
Hi Gary.

You have a " Permanent-Split Capacitor Motor " fitted, quite uncommon !

Have a look here, useful information.   https://www.allaboutcircuits.com/textbook/alternating-current/chpt-13/single-phase-induction-motors/

Probably 99% capacitor faulty.

Cheers Graham.

Offline Admiral_dk

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Re: Mill motor question
« Reply #18 on: January 11, 2020, 08:15:49 PM »
Quote
You have a " Permanent-Split Capacitor Motor " fitted, quite uncommon !

Interesting as that is the most common older motortype here in Denmark, in the 200W to 1.5KW range .... all bigger ones used to be 3 phase, and really small ones the shadow pole type .... Now really many new ones are either DC or 3 phase run from an electronic speed/load controller and not directly from mains.

I have NEVER seen a motor with the centrifugal switch here - that is not to say that there isn't any here, but I haven't seen them.

Offline galland

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Re: Mill motor question
« Reply #19 on: January 19, 2020, 01:14:41 AM »
My new capacitor arrived today and it did the trick. Had to order one on ebay because all the shops in town that used to repair motors and carry parts have closed their doors.
Thanks for all the tips and thank you Graham for your valuable input.     Gary

Offline Jo

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Re: Mill motor question
« Reply #20 on: January 19, 2020, 07:48:30 AM »
Pleased to hear you are up and running again Gary  :ThumbsUp:

Jo
Enjoyment is more important than achievement.

Offline Alyn Foundry

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Re: Mill motor question
« Reply #21 on: January 19, 2020, 11:14:18 AM »
My new capacitor arrived today and it did the trick. Had to order one on ebay because all the shops in town that used to repair motors and carry parts have closed their doors.
Thanks for all the tips and thank you Graham for your valuable input.     Gary

Very pleased to read that the repair was successful Gary.  :)

Cheers Graham.