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View JimYoung's profile

Table Saw Motor Problem - No torque

by JimYoung
posted 12-20-2018 07:21 PM


11 replies so far

View Phil32's profile

Phil32

632 posts in 415 days


#1 posted 12-20-2018 07:43 PM

It sounds like you’re guessing about several parts of this problem. Exactly what motor are you dealing with? What is the exact load capacity of your electric panel and this circuit? How can anyone on this site give you good advice without knowing these answers? It sounds like you need a qualified electrician.

-- Phil Allin - There are mountain climbers and people who talk about climbing mountains. The climbers have "selfies" at the summit!

View JimYoung's profile

JimYoung

330 posts in 2098 days


#2 posted 12-20-2018 08:09 PM

The electrical panel is wired for 220V with two ganged 20A circuit breakers. Like I said, the motor had been running fine for at least year in this wiring configuration and with this power source, so I don’t think it is the electrical panel. I did double check to make sure both breakers were on.

I don’t have the exact motor model number, but according to the Powermatic manual I found online it is a 1 1/2 hp, 115V/208V, 1 phase motor, assuming it is the original motor.

From what I know about AC motors, a bad start capacitor will cause the motor to not start. My motor is starting, but just doesn’t have much power. I couldn’t find anything on this site with those symptoms, and thought someone might have some ideas where to start looking.

Again, any help is appreciated.

-- -Jim, "Nothing says poor craftsmanship more than wrinkles in your duck tape"

View Kazooman's profile

Kazooman

1359 posts in 2464 days


#3 posted 12-20-2018 08:15 PM

Note:Written while Jim was typing.

If the saw ran fine for a year on the 220 circuit and you have not recently added anything else to that circuit or a big draw on the overall panel you should probably check out a few things before calling an electrician. Since you were comfortable reworking the panel and wiring on the motor in the past, it seems like you would be comfortable with checking all of the connections to look for any obvious issues like loose wires or corrosion. You can use a simple meter to see just how much current the saw is drawing on start-up and when running. The easy way to check for an overloaded circuit is to just try another circuit to see if the problem persists. Since you presumably don’t have a second 220 circuit in the shop, you could swap the wires back to 110 and see if the problem persists on other circuits.

If the saw still balks, start checking out the obvious mechanical issues. Remove the belt and check to see that the arbor turns smoothly and do the same for the motor. The bearings in either could be shot and they would be a cheap and relatively easy fix. While the belt is off you could recheck the current draw with no mechanical load. Is the motor a totally enclosed type? If not then you can get a buildup of sawdust internally that can result in binding. Another easy (free) fix: open up the motor and blow out the inside. If you have gotten this far without solving the problem, then you can look to other mechanical or electrical issues in the motor itself. You can check capacitors with a meter and replacements are cheap. If you don’t want to really start pulling things apart (and I don’t blame you) you can take the motor to a shop for an overhaul.

As a final, last ditch solution, you can jack up the miter gauge and wheel a new SawStop under it. That should get you going in short order!

Good luck with your troubleshooting.

View CaptainKlutz's profile

CaptainKlutz

1892 posts in 2006 days


#4 posted 12-20-2018 11:22 PM

+1 Check motor. Doubt the power circuit suddenly when bad, when it worked for last year.
regardless,
- Check voltage to confirm circuit is ok during start and run.
- Check belts for signs of glazing and/or slipping, replace if needed
- Remove belts and check arbor and motor bearings to ensure they turn smooth.
- Remove back fan cover from motor and check centrifugal switch for debris. Clean and try again. If the switch is not switching off the start capacitor, can have low torque condition.
- If current draw is within spec’s, would anticipate loose/corroded connection, or a bad run capacitor assuming your saw has one.
If no run capacitor and no loose connections and new belt and working centrifugal switch, maybe time to let a motor shop test the motor on a bench.
Best Luck.

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View diverlloyd's profile

diverlloyd

3641 posts in 2369 days


#5 posted 12-21-2018 01:59 AM

I would start at the panel and check to see if you are getting power on both legs of the breaker. Then work out from there. It sounds like the motor isn’t getting the power that it is wired for.

View mrg's profile

mrg

860 posts in 3511 days


#6 posted 12-21-2018 05:37 AM

Reading your post, you said the belt would squeal when started from the torque. I would check bearings and pulley’s.

-- mrg

View jamsomito's profile

jamsomito

433 posts in 937 days


#7 posted 12-21-2018 06:00 AM

I just had the same issue (tripping breaker on start or under load), and I have the same saw as you (PM63). I made a troubleshooting thread – it is a bit long but lots of good info there: http://lumberjocks.com/topics/299889

For me, replacing the bearings in the motor did the trick. If your motor is original, it’s probably overdue for the same. Also check the capacitor, windings continuity, windings short to ground, arbor bearings, and belt. Not much else to look into other than that. Good luck.

View JimYoung's profile

JimYoung

330 posts in 2098 days


#8 posted 12-27-2018 05:53 PM

Hi Guys,

Thanks for the tips so far. I had some time to tinker with it today, and I haven’t been able to find anything out of the ordinary. Here is what I’ve checked so far:

1.) 220V outlet – 120V from each prong to ground and 240V across both prongs, so outlet is good.
2.) ON/OFF switch – all wiring is tight and continuity from plug to motor wiring.
3.) Starting Capacitor – Not leaking or bulging. With an Ohm meter the resistance starts at 0 Ohms and slowly increases, so cap is not shorted or open.
4.) Motor windings, Ohm meter shows about 1 Ohm on each winding, and about 2 Ohms across both when they are wired up. Windings are not shorted to the motor housing/ground
5.) I found some lose crimps in the motor wiring, so I tightened those up and double checked the wire order/connections.
6.) Removed end fan cover. A little dusty but the starting cap clutch is in good order and I hear it reset as the motor winds down.
7.) Motor spins freely, arbor spins freely, belt is in good shape.

I grabbed a piece of walnut, and can stop the blade if I feed it too quick. ) ^ :
It sounds like it is not spinning up to full speed like in the past. Just doesn’t have the same whirr off the blade.

Some photos of the motor and starting cap.

I’m at a bit of a loss. Anything else I can check?

-- -Jim, "Nothing says poor craftsmanship more than wrinkles in your duck tape"

View Alan72's profile

Alan72

221 posts in 2544 days


#9 posted 12-27-2018 06:08 PM

have you look to see if there is any electrical motor shops in the area, When I got my Sawstop my motor was toast right out of the box. I took it to the shop and the guy tested it for me free of charge. It’s alot cheaper to replace the motor then to buy a new saw.

View JimYoung's profile

JimYoung

330 posts in 2098 days


#10 posted 12-27-2018 06:13 PM

Doh! I double checked the belt, and the motor was at the end of the stops for tensioning the belt. I made a quick adjustment, and it cuts like a champ!

It is a link belt, so I’m not sure if I can remove a link or two, or just stick a crowbar in my wallet and buy a new one.

Thanks again for the help.

-- -Jim, "Nothing says poor craftsmanship more than wrinkles in your duck tape"

View Scap's profile

Scap

80 posts in 438 days


#11 posted 12-27-2018 06:29 PM



Doh! I double checked the belt, and the motor was at the end of the stops for tensioning the belt. I made a quick adjustment, and it cuts like a champ!

It is a link belt, so I m not sure if I can remove a link or two, or just stick a crowbar in my wallet and buy a new one.

Thanks again for the help.

- JimYoung

Shorten that belt a bit, sounds like you’ll be good to go after you get better belt tension.

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