Table saw no power

EwokArcher · April 28, 2016, 09:51:00 AM

Hey guys, my father in law gave me what could be a very nice craftsman table saw, it's a big upgrade from what I have now if I can get it running.
It's issue: turn on the power and you can hear the motor kick on but only very minimal power is getting to the blade. The blade will barely start spinning without assistance, and never gets to cutting speeds. Where shold I start?
I could try to repair it, I could try to cannibalize my old table saw motor and use it on this much nicer craftsman table. I also have a bunch of electric motors ranging from 1/4 to 1/2 hp but I'm sure mounting would be a big issue there
Thanks for your help guys.

jess stuart · April 28, 2016, 11:12:00 AM

You could look into having the old motor rebuilt, that would take care of any mounting issues. Probably a little less cost than a new motor as well.

Bowjunkie · April 28, 2016, 11:16:00 AM

I'd get a direct replacement.

Incognito1 · April 28, 2016, 03:22:00 PM

Capacitor?

EwokArcher · April 28, 2016, 03:29:00 PM

I'll open it up today and see if there is anything obvious.

Incognito1 · April 28, 2016, 03:35:00 PM

Bad capacitors often have bulging areas or leakage.

fujimo · April 28, 2016, 05:25:00 PM

in the smaller motors i have found the new are the same price and sometimes cheaper than rewinds. but still worth making some enquiries.
but my first thought was the capacitor too- an easy, cheaper place to start.

does the motor( a lot of the older ones do) have grease nipples for greasing the bearings.
grease could either be old and dried up, or possibly been over greased.
i had a 5hp 3 phase motor refuse to spool up simply due to over greasing on the driven end- but bought a new motor first before i fuggered that one out :mad:

if you think you might have overgreased- take the bearings out flush with gas- replace- and lightly grease

passion for knowledge · April 28, 2016, 06:59:00 PM

Are you sure the motor is not producing power?

Could be that the power is getting lost before it gets to the blade.

As fujimo points out, lubrication could be the problem. Not sure about over-greasing.

Try oiling anything that moves.

EwokArcher · April 28, 2016, 10:42:00 PM

I can hear the motor engaging and it sounds like it is under a load, but I'm getting very minimal rotation at the blade. I can give the blade a little jump push and it will have just enough juice to maintain a very minor rotation of the blade.
From a stand still when I turn on the power the motor starts humming but I get 0 rotation.
I'll try to post a pic I took earlier. I'll have to look into the grease issue.

EwokArcher · April 28, 2016, 10:49:00 PM

This is not a very helpful image but it is the only one I have at this time. I'll look into the grease issue and see if I can tell anything about it tomorrow. I'm not sure what to be looking for on the capacitor, what would that look like on this unit?

fujimo · April 28, 2016, 11:59:00 PM

sounds more and more like the capacitor. can you find the capacitor?
get the numbers off it and get a new one- after cleaning all connections etc- especially if it has been sitting for a long time- as this one has.

mikkekeswick · April 29, 2016, 03:55:00 AM

Personally I'd buy a new motor. There are a few different configurations of mounting holes and plate shape but not many. Any place that sells motors will be able to help you out. I'd also go for a 1/2hp over what it runs now.

Bowjunkie · April 29, 2016, 06:38:00 AM

With the switch off, does the shaft spin free by hand?

It sounds like the capacitor may be bad. Do you have a volt/ohm meter and are you capable of discharging, troubleshooting and replacing the capacitor?

Is all the voltage getting there? Switch ok?

If you're not comfortable with such electrical repairs, it would probably be better to just replace the motor with a new one. There are some on the big auction site, not sure if they're compatible with yours but it may be worth a look.

EwokArcher · April 29, 2016, 11:21:00 AM

Is it possible this little motor does not have a capacitor? They are typically on the side of the outside of the motor correct?

The shafts does spin freely without power.

Also, I have all of these functioning electric motors I picked up at an auction for 2$ each. Guess there is nothing I can do with these.

EwokArcher · April 29, 2016, 12:27:00 PM

Thanks for the help guys, I'm gonna price around for a replacement.

Robertfishes · April 29, 2016, 12:39:00 PM

Try cleaning with compressed air..blow the saw dust out of motor..

Bowjunkie · April 29, 2016, 03:37:00 PM

All single phase 120 volt motors have a capacitor. Without a capacitor to 'give it a direction', it would just sit there and hum. It may be internal.

Incognito1 · April 29, 2016, 06:55:00 PM

I don't believe your saw has a capacitor. The thing next to the switch is a relay that has to be in the proper upright position or it will shut the saw down. I don't think that's it, but something to be aware of when testing. I'm thinking the start windings may be burned. I'd take the motor out, open it up and clean everything good then reassemble and test before buying a new one......if you can even find a replacement. If you take it out, look for carbon brushes and make sure they are making good contact. There is a possibility that you don't have carbon brushes on that saw either though. Also, take a good whiff of the motor and see if there is a burnt smell. Sorry I can't be more help. What is the model number of the saw?

kennym · April 29, 2016, 08:29:00 PM

I'm no electric guy but that switch looks suspect. I had a saw like that one and don't think that is original.

OK electric guys: Can the switch be wired wrong and make it do that? Or low voltage from something under that tape?

Bowjunkie · April 29, 2016, 09:19:00 PM

Ken, I didn't notice the switch. From what I can see in that wiring, it looks like, possibly, the original switch shorted (always on, whether in the on or off position), then the hot wire was cut that supplied power to either it or the motor, and a toggle switch was inserted to function as the off/on switch... not the way I would have done it, as you'd be relying on a failed switch to carry the current needed to run the saw. When the contacts in it fail, they can melt/stick together, but with burns, cinders, or other less conductive material between them, and yes, this can keep the motor from getting enough voltage to run properly. It could even eventually burn the motor up.

If they bypassed the old switch entirely, as far as the hot(black) wire goes, it's possible the toggle switch they added wasn't rated for the current and it failed.

Either way, it's possible replacing the switch(s) with an OEM/replacement version may solve the whole problem.

One with some electrical experience could bypass the hot wires of both switches and if the balance of the wiring and the motor and capacitor was ok, it would run normally, thus pinpointing the switch as the problem, and be replaced.