table saw tripping

[Paul Saffold]

I have a Jet contractors saw bought new in late 1990s. The date on the motor is 1995, 3450 RMM, 18 amp (listed 1.5hp).

It is under powered. I knew that when I bought it, but that’s what I could afford at the time but it was a huge step up from a 9” sears saw.

I have always had to take shallow cuts when ripping 8/4 stock or the motor would trip. Any 8/4 stock - pine, oak, pressure treated.

The motor reset is tripping, not the circuit breaker in the panel.

Lately it seems to trip more. Recently I was ripping 3/4” plywood to make an adjustable router circle cutting jig and it tripped again.

It is on a 20 amp circuit.

I clean the blades regularly. I was using a 50 tooth combination Freud blade, reasonably sharp. New blade on order just in case.

So, what say you guys and gals with experience with this? Repairable? I’m pretty handy and fix things myself. Or?????

[Frank Pratt]

Check the pulley alignment. Perhaps one of them has wandered.

[Zachary Hoyt]

I had a DeWalt 733 planer that would trip the overload protection on the motor all the time. It was very annoying. Finally I decided that since I had bought it for $120 and already gotten that much use out of it I would just remove that part and connect the wires together. It ran like that for about another 10 years, and was much more useful. When I decided to replace it the motor was still good, but the belt had begun to jump off the pulleys and I didn't want to mess with it when I had a few hundred board feet of hardwood to plane. I would try bypassing the overload and see what happens. It sounds like it may have been defective from the start. You don't have much to lose, and may have much to gain, potentially.

[Doug Colombo]

I had an old sears ts that had the same issue. Bottom line was that the thermo breaker on the motor went bad and would trip under small loads that is handled in the past with no issue. You could try to use a thin kerf blade (if you haven’t done that yet) to reduce load on the motor. If it still trips, you can get the motor breaker replaced. My saw was from the early 50’s and the way and type of breaker that was used then, replacement was going to cost more than a new motor, so I just bought a new Lesson motor. Not sure which would be the most cost effective way to go with your motor but worth checking out the costs.

[Lee Schierer]

My saw is a 1980's craftsman with a 1 Hp motor. I can easily rip 2 x 4 lumber on my saw using a dedicated ripping blade without tripping the motor thermal protector. It isn't as fast of a cut as I would get on a 3 or 5 hp saw but it does the job. A few thoughts:

1. Does the saw have start and run capacitors? If so one or both could be bad.

2. Is the motor too hot to touch right after the motor reset trips? If not the thermal protector is probably bad.

3. When ripping try using a 40 tooth ripping blade instead of the combination blade. They do work better than combination blades particularly when making heavy rips in 8/4 lumber. Perhaps your combo blade is dull or dirty from accumulated sap.

[Bill Dufour]

Any small gauge extension cords will cause voltage drops and motor overheating as it draws more amps to make up for under voltage.
Bill D

[William Hodge]

I had a saw with a key way on the sheave on the arbor. The set screw on the keyway loosened, and the key slid out and was rubbing on a casting at 3450 rpm or however fast a saw blade spins. The casting has a nice groove worn in it now. The thing could have caught fire. I noticed, because the saw blade slowed down faster than normal when I shut the power off. I never tripped the breaker or reset on that saw.

I suggest opening up the saw and seeing if all the moving parts are moving as they should. I would take the motor out and screw it to a bench, and see how it runs. If you don't find anything, take the motor to an electric motor shop, and have it checked out.

As stated above, the power supply to the saw should be 12 gauge wire, short runs, in good condition. The outlet needs to be be the right voltage and amps.

[Cameron Wood]

+1 on Zachary Hoyt's approach- eliminate the thermal reset. Most motors don't have one.

[Warren Lake]

if you take the thermal overload out you will probably burn out the motor.

Sears had some bad thermal overloads, had a radial for cross cutting rough. Waste of time. Ended up using the skill saw and no more issues.

[Cameron Wood]

if you take the thermal overload out you will probably burn out the motor.

Sears had some bad thermal overloads, had a radial for cross cutting rough. Waste of time. Ended up using the skill saw and no more issues.



Of approximately 15 stationary motors in my shop, I think one has a thermal overload. None of them has burned out.

[Warren Lake]

His saw burned cause I took the thermal out. Thermal was there to protect it.

[Richard Coers]

Definitely something wrong with the overload switch. I don't think they would have that many cycles in them, so all those trips over the years may have been the culprit. If you consider how fast you can rip plywood with a hand held saw, that saw should fly through plywood. Do you have enough money now to upgrade? I'd say time for a real table saw.

[Zachary Hoyt]

Sears made some pretty poor quality motors too. I burned up 3 or 4 Craftsman table saw motors in older saws that I bought, and then I finally bought a used Delta contractor's saw and it was much better and lasted till I sold it after buying a Unisaw 10 years later. The OP has a Jet table saw so I would think the motor would be better quality. Might as well take the overload protector out of the circuit and see if it works better. If the motor does fail a new one can be bought, or a new saw, but there's no point replacing the saw until then unless the OP wants something different anyway.

[Ken Combs]

Another vote for a thermal overload issue. I wouldn't jumper it, but replace it with a new one. While in there be sure it isn't packed with dust, lots of them are and restricts the airflow.

Also, check the supply voltage under load just to be safe. 50T combo blade is not a good choice for 8/4 stock of any kind.
,
1.5 HP should be fine for most home use. I've used 1 and 1.5 for years with no issues like that. I have a ancient Unisaw with a 1hp bullet motor that is a beast, for a 1hp.

[Frank Pratt]

Of approximately 15 stationary motors in my shop, I think one has a thermal overload. None of them has burned out.
You sure about that? Many motors have overloads that are entirely internal and you can't see them from outside the motor. The kind of motors that are permitted to not OL protection are low power, low torque type that will just stall out without overheating. 3 phase motors do not have integral OL protection because the starter provides that. Some have a sensor embedded in the windings that connect to the starter coil for motor protection.

[William Hodge]

You sure about that? Many motors have overloads that are entirely internal and you can't see them from outside the motor. The kind of motors that are permitted to not OL protection are low power, low torque type that will just stall out without overheating. 3 phase motors do not have integral OL protection because the starter provides that. Some have a sensor embedded in the windings that connect to the starter coil for motor protection.

My good motors don't have thermal overload buttons visible. I saw a guy running a three phase 7 1/2 hp 14" saw rough cutting lifts of 8/4 cherry. The overload on the magnetic starter kept tripping, and he kept resetting it. Finally, the motor just shut down very hot. The next day the motor started up and ran. There must have been an internal thermal overload.

[Paul Saffold]

Frank, I liked your suggestion because it was the easiest to check but the pulleys are inline.

[Paul Saffold]

My saw is a 1980's craftsman with a 1 Hp motor. I can easily rip 2 x 4 lumber on my saw using a dedicated ripping blade without tripping the motor thermal protector. It isn't as fast of a cut as I would get on a 3 or 5 hp saw but it does the job. A few thoughts:

1. Does the saw have start and run capacitors? If so one or both could be bad.
I don't know.
2. Is the motor too hot to touch right after the motor reset trips? If not the thermal protector is probably bad.
No the motor has never been hot.
3. When ripping try using a 40 tooth ripping blade instead of the combination blade. They do work better than combination blades particularly when making heavy rips in 8/4 lumber. Perhaps your combo blade is dull or dirty from accumulated sap.
When I rip I use a 24 tooth thin kerf blade unless I only have a few cuts to make and the stock is 4/4 or less.

[Paul Saffold]

Any small gauge extension cords will cause voltage drops and motor overheating as it draws more amps to make up for under voltage.
Bill D

The saw is plugged into a 20 amp circuit without an extension cord.

[Paul Saffold]

So I opened up the saw . Everything looks normal. Ran the motor without the blade. Sounds normal.
Opened the case for the motor circuit protector. Clean no sawdust there. Blew out the fan end of the motor. Very little dust there either.

Looked online for a new thermal protector. $72 + tax + shipping. Special order. 3 weeks unless backordered, then longer.

So in the meantime how do I jump this thermal protector out? Looks to me like I should take the white wire off the screw terminal below the red/yellow wires (feeding the thermal protector), take the black wire off of the thermal protector and screw it to the terminal below the red/yellow wires.

498499

[Cameron Wood]

You sure about that? Many motors have overloads that are entirely internal and you can't see them from outside the motor. The kind of motors that are permitted to not OL protection are low power, low torque type that will just stall out without overheating. 3 phase motors do not have integral OL protection because the starter provides that. Some have a sensor embedded in the windings that connect to the starter coil for motor protection.

Well, I'm sure about the second part- none have burned out, and none have needed any reset.

[Paul Saffold]

found a second source for $60 +s&h. I will order one if bypassing the reset works which it sounds like it will.

Thanks for all the comments and suggestions.

[Bruce Wrenn]

Get a "KilloWatt meter and check actual current draw. I bought mine at HF. Or if you can make a short cord set that you can separate the conductors, use a clamp on amp meter to check current draw. If draw isn't more than name plate on motor, then overload is bad. Overloads are a generic item, and can be ordered from multiple sources. You could mount a new one in a 2X4 handy box thru which the line set passes.

[Cameron Wood]

So I opened up the saw . Everything looks normal. Ran the motor without the blade. Sounds normal.
Opened the case for the motor circuit protector. Clean no sawdust there. Blew out the fan end of the motor. Very little dust there either.

Looked online for a new thermal protector. $72 + tax + shipping. Special order. 3 weeks unless backordered, then longer.

So in the meantime how do I jump this thermal protector out? Looks to me like I should take the white wire off the screw terminal below the red/yellow wires (feeding the thermal protector), take the black wire off of the thermal protector and screw it to the terminal below the red/yellow wires.

498499


yes, or wire nut or butt splice the two wires together.

[Dave Sabo]

Lot of good suggestions and practices mentioned here but, this is your problem:


50 tooth combination Freud blade, reasonably sharp


Get a 20 to 30t dedicated rip blade for 8/4 stock. Thin kerf wouldn't hurt either, but that'd be dealers choice.


p.s. your blade isn't as sharp as you think it is either.

[Paul Saffold]

Lot of good suggestions and practices mentioned here but, this is your problem:




Get a 20 to 30t dedicated rip blade for 8/4 stock. Thin kerf wouldn't hurt either, but that'd be dealers choice.


p.s. your blade isn't as sharp as you think it is either.

Dave, apparently you missed my earlier post.

[Warren Lake]

ripping solid with a combo is brutal compared to a rip blade. Doesnt sound like the problem as you tripped on plywood but its one of them. Every one works a different speed or how they push a table saw. its easier to work with more powerful stuff.

[Lee Schierer]

So I opened up the saw . Everything looks normal. Ran the motor without the blade. Sounds normal.
Opened the case for the motor circuit protector. Clean no sawdust there. Blew out the fan end of the motor. Very little dust there either.

Looked online for a new thermal protector. $72 + tax + shipping. Special order. 3 weeks unless backordered, then longer.

So in the meantime how do I jump this thermal protector out? Looks to me like I should take the white wire off the screw terminal below the red/yellow wires (feeding the thermal protector), take the black wire off of the thermal protector and screw it to the terminal below the red/yellow wires.

498499

Can you post a photo of the connections diagram for the motor. It should be on the cover of that box.

[Paul Saffold]

498517498517

Rather than cutting the tab off the wire to jump out the switch, I'll leave it.. Then when the new switch comes in I can plug it in. I found another source and it should be here in a couple of days. I am more comfortable using the saw with the thermal protection in place.

[Jim Dwight]

I think you found your solution. You had already checked a lot of what I would start with. In other words, I agree the issue is likely the thermal overload. Bypassing it is not risking anything more than the motor. Bypassing it for a few minutes to see if the saw runs well is not risking anything.

I have used 110V table saws for about 50 years at this point. My current one is a PCS with the 1.75hp motor. I don't think it is "under powered" but it does not have power enough to let me use a blade that is quite dull, dirty, or not suited for the work I'm doing. The thermal overload on mine seems to be set too low and it trips quite easily. The last time I was ripping some 3 inch thick softwood for legs for a bunk bed and I kept trying different blades to get it to complete a cut. The kerf was closing up as tight as it could go on the riving knife and pinching the blade a little. I got the cuts done with a thin kerf ripping blade I had on hand that was not close to new but was still not terribly dull and was clean. I rip 2 inch thick hardwood any time I need to. Normally a 50 tooth combination blade is on the machine and I'll use it. But I have largely shifted to thin kerf blades. They are not miracle workers but seem to add a little margin which the saw can use.

[Dick Strauss]

18A motor on a 20A breaker? 125% of 18A is 22.5A. The cb should be at least this size (22.5A) with wire to match (the next size up is 25A but these can be hard to find for some panels so go preferably with a 30A cb with 10g wire).

[Lee Schierer]

18A motor on a 20A breaker? 125% of 18A is 22.5A. The cb should be at least this size (22.5A) with wire to match (the next size up is 25A but these can be hard to find for some panels so go preferably with a 30A cb with 10g wire).

A motor pulling 18 amps would be 2.5 HP not 1.5 unless Jet was listing motors with peak amperage like Craftsman used to do. If it was drawing that many amps while running it surely would have tripped a 20 amp breaker on start up.

[Dick Strauss]

Here's my logic on this saw...18A*120V*.70 (efficiency) leaves the motor at about 1500W (under 2hp max) so I assume the motor is rated at 1.5hp or the next usual step down.

[Rod Sheridan]

18A motor on a 20A breaker? 125% of 18A is 22.5A. The cb should be at least this size (22.5A) with wire to match (the next size up is 25A but these can be hard to find for some panels so go preferably with a 30A cb with 10g wire).

Hi Dick, that’s for continuously operated or thermostatically controlled loads, not an intermittent machine like a home saw.

20 ampere circuit is just fine for the saw in question……Regards, Rod.

[Paul Saffold]

The thermal switch was supposed to be delivered March 30, 2 days after ordering, then delivery on or before the 6th, then on or before April 10th....
So I called them and was told it ships from a 3rd party. I let them know how unhappy I was that they did not tell me it was backordered. I have not received any communication from them or the 3rd party vendor. I know of the change delivery dates because I check the website. globalindustrial.com

[Paul Saffold]

Update.
So the thermal switch came in and changed out. The saw has been working fine now. Ripping pressure treated 2x without any problems in my shop flooring upgrade.

[Curt Harms]

Get a "KilloWatt meter and check actual current draw. I bought mine at HF. Or if you can make a short cord set that you can separate the conductors, use a clamp on amp meter to check current draw. If draw isn't more than name plate on motor, then overload is bad. Overloads are a generic item, and can be ordered from multiple sources. You could mount a new one in a 2X4 handy box thru which the line set passes.

This would be my tack. I have an 'appliance' cord about 6' long - I guess intended for heavier 120 volt loads like window air conditioners or toaster ovens. I was able to split it so am able to clamp an ammeter around one conductor. The easiest way I know to check the actual amp draw of a machine or other load. If the overload is tripping while the saw is drawing substantially less than its rated amperage, that pretty much indicates your problem.

[Rich Engelhardt]

Update.
So the thermal switch came in and changed out. The saw has been working fine now. Ripping pressure treated 2x without any problems in my shop flooring upgrade.
So - it was the thermal switch after all.

Thanks for the update!