tablesaw motor going?


A long While ago, my craftsman TS motor (about 2 years old at the time), it's a 1 1/2 hp 13 amp induction motor started showing the following symptoms: When I turned the machine on, the motor would not turn over, but would hum and only threaten to start, i.e. the blade would move only slightly, then, it would either finally start spinning on its own, or with a careful push with a block of wood, it would finally kick in. The motor was obviously drawing some extra amps in the process, as my lights would dim until it started spinning. Fortunately, the problem stopped for about a year or so, but it is happening again lately. Is the motor on its last legs?
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Doug wrote:

Sounds like you need either a new starting capacitor or the centrifugal switch that controls it.
BTW, it is a common problem.
Once you get it corrected, consider rewiring and operate at 240VAC rather than 120VAC.
Lew
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As it slows down, listen carefully for a click that indicates that the centrifugal switch is resetting. Could be full of dust or has a broken spring and is not resetting to the start circuit.

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Doug wrote:

No. That is typical when the start mechanism is malfunctioning. Might just be some saw dust between the contacts, burned contacts, or the centrifugal mechanism is gummy. I would start with blowing the beejeebers out of the motor with an air hose (compressor). If that doesn't work, you may need to take the end caps off the motor to directly check the start mechanism.
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I had a similar problem a couple of years ago.
http://groups-beta.google.com/group/rec.woodworking/browse_frm/thread/523ba50d7d21580b/8362d2d7a665e80e?lnk=st&q=motor+group:rec.woodworking+author:watson&rnum=7&hl=en#8362d2d7a665e80e
The final fix was to blow out the caps and then hit the end of the shaft with a ball peen hammer to knock the gunk off the contacts.
I know it sounds brutal, but, in my case, it did the trick.
Tom Watson - WoodDorker tjwatson1ATcomcastDOTnet (email) http://home.comcast.net/~tjwatson1/ (website)
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Tom Watson wrote:

If it is a sleeve bearing motor, NBD; however, if a ball bearing unit, there is a distinct chance of brinelling the ball bearing races unless there is an adequate thrust bearing.
If you brinell the bearings, you will know it in a hurry.
(Bearings start to chatter)
Lew
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On Sun, 31 Jul 2005 22:54:22 GMT, Lew Hodgett

I think that you chimed in on my fix, Lew.
I was faced with a motor that would hum but not turn, even after blowing everything out.
It was a case of a few judicious hits with the BP, or laying out $300.00 +.
I was fortunate enough to knock off the crispiness without creating further problems, and the bad boy is still running just real good.
I think it has something to do with getting to a point where you understand what is going on inside the mess, and then whacking things while you're seeing the mess in your head.
Tom Watson - WoodDorker tjwatson1ATcomcastDOTnet (email) http://home.comcast.net/~tjwatson1/ (website)
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<snip>

The key phrase there is "seeing the mess in your head." An ignorant whack with a bfh costs $300 most of the time. Or more.
What's the quote? "Anyone who thinks education is expensive should try ignorance?"
Patriarch, leaving the hammer be...
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Patriarch wrote:

Right on! Whacking a hammer with a hammer is right up there with wrenching every nut to 120 ft-lbs, which works wonders on 1/4" bolts.
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Tom Watson wrote:

I think you limited your options. You left out the option that a really cheap person always takes. That is, remove the end caps and check everything out. Sometimes the contacts are burned and just whacking the endplate won't fix burned contacts. You have to file and burnish the contacts or replace them.
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Could be arbor bearing which will create similar symptoms. Remove the belt and see if the blade spins freely.
A starting capacitor would produce similar results.
Doug wrote:

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