# Radial Arm Saw Motor Problem



## Napes1 (Mar 22, 2011)

I have a 1997 Sears Craftsman Radial Arm Saw 113.197150 that's virtually new. I bought it from a fellow that got it as a gift and never put it together. It sat in the box in his garage for a decade. Well, I bought it, assembled it and plugged it in. It worked, but only for three cuts! It only hums when I turn it on. It also trips the breaker on my power strip. Thinking I could take the motor to the local Sears Store for repair was laughable. First they told me they could only accept the whole saw for repair (this while I was standing there with motor in hand). Then they gave me a number to call for service. It took 20 minutes for the customer service operator to understand that a Radial Arm Saw was not a lawn mower! When he finally found the model in his database he scheduled a home visit by a repair technician.

He came today. Now, that was a joke! This guy had never worked on a saw motor and didn't know the first thing about trouble shooting it. He spent the hour he was here on the phone to his "guy who knows this stuff" while I was showing him how to crack the case to access the capacitor for testing. He fumbled with his testing gear and pronounced the capacitor bad. But, it could be the centrifugal switch. He wasn't sure. Of course, he wasn't carrying any parts. Would I like to order them for installation at an additional labor charge? For this "service call" I paid $96 and sent him on his way.

A capacitor costs a mere $4, Sears Parts has the switch for $21. The local Grainger Store had the correct capacitor in stock so I took the old one with me to test and buy a new one. Their testing equipment showed the old capacitor functioning at just under spec, but I bought a new one anyway. They couldn't find an appropriate centrifugal switch. After installing the new capacitor I still get only a hum. I even tried by-passing the power strip and plugging straight into an outlet. No luck.

My question for all you experts out there is; how likely is the problem to be a centrifugal switch? Am I throwing good money after bad? The whole motor and assembly can be purchased from Sears for $159 and if I take it to my local repair shop it will cost another $100 with no guarantee of success. I'm already past half way there!

Napes


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## cabinetman (Jul 5, 2007)

If you have a meter, check the voltage at the switch, and at the motor. You don't need a blade mounted to do this test.












 







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## Napes1 (Mar 22, 2011)

Thanks for the tip, cabinetman. The voltage reads 123 going into the switch and 108 going out to the motor. The fuse tripped while I was testing the motor. Something sinister is going on inside the motor, could smell burning after the test.


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## rrbrown (Feb 15, 2009)

First off the centrifugal switch should not stop it from starting like that. That switch is hooked to the start capacitor and windings after the motor starts, the switch opens breaking the circuit. Now if the contacts at that switch were bad you could have a loss of current causing the hum. 

The burn smell is a concern. Either there is a short between the start and run windings which would trip a breaker and give a burn smell. The other issue could be the arbor is froze or jammed. I would unplug the saw and try to spin the blade. a bad bearing could cause drag on the motor and make it over amp. a foreign object inside the motor (less likely) could also be keeping the motor arbor from spinning. Both situations could cause over amping which trips a breaker and will give a burn smell.

The bad news is that if there is a short between the motor windings, that motor is probably made in china and not able to be rebuilt. That is a problem with some china motors, the coating they put on the winding wires is not as good or as well done as American and Taiwan made motors but they are getting better. 
I hope this helps


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## RetiredLE (Jan 20, 2011)

I had the same problem with an older model Craftsman table saw that I purchased recently.

The motor wouldn't come up to speed in the seller's small shop but when I got it home and plugged it in, the motor ran fine. Wonder if the problem might be in your wall circuit and not the motor........


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## woodnthings (Jan 24, 2009)

*Hot wire it!*



Napes1 said:


> Thanks for the tip, cabinetman. The voltage reads 123 going into the switch and 108 going out to the motor. The fuse tripped while I was testing the motor. Something sinister is going on inside the motor, could smell burning after the test.


Bypass the switch to see if that's the issue. Of course wire all connections, first...then plug it in...no power strip either...just direct to wall out let.....too many variables...reduce to the least no of potential problem sources.
Measure voltage at the wall and the hot wires, it should be the same. 150 V or 230 V with a double pole switch? :blink: bill


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## firemedic (Dec 26, 2010)

Napes1 said:


> Thanks for the tip, cabinetman. The voltage reads 123 going into the switch and 108 going out to the motor. The fuse tripped while I was testing the motor. Something sinister is going on inside the motor, could smell burning after the test.


I don't remember the wiring schematic all that well... Where in-line is the thermal overload? Before or after the capacitor?

108v is not enough of a drop to keep the motor from starting. If the saw can be wired for either 110v or 220v I suggest looking over the wiring diagram (inside the capacitor cover I think) and make sure that checks out. Otherwise if nothing electrical wrong... Only thing left is physical.... So as above see if it free spins...

My 2 cents...

~tom


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## Napes1 (Mar 22, 2011)

Thanks for all the tips.

The motor is free to turn, so nothing's jammed.
I bypassed my power strip to go directly into a 110V wall socket (it still tripped the breaker switch in the main terminal box after about 20 seconds).
I checked to make sure it is set to run on 115V not 230V.
The motor is from 1997, so I don't think it's Chinese (the original capacitor was made in the USA).
I even took a 400 grit paper to the contacts between the switch and the plate.

:thumbdown:


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## rrbrown (Feb 15, 2009)

Napes1 said:


> Thanks for all the tips.
> 
> The motor is free to turn, so nothing's jammed.
> I bypassed my power strip to go directly into a 110V wall socket (it still tripped the breaker switch in the main terminal box after about 20 seconds).
> ...


Sounds like it could be the windings. Looks up electric motor service it would be the best bet. You can bring it to them. There not Sears.


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## Napes1 (Mar 22, 2011)

Just to wrap up this discussion. I bailed out on fixing the motor. Just installed a new one from Sears Direct. Cost $159 and works great.


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## rrbrown (Feb 15, 2009)

Thanks for posting. :thumbsup:


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