TS Motor stopping periodically.

Hi,
maybe someone could suggest what is going on with my TS lately. I have an older Beaver contractors table saw. which has a 3/4 110 v motor and a magnetic switch.
When I use the saw with a standard rip or combination blade it runs fine. But, if I use a dado blade after a while the motor shuts off. If I try to start it right away it won't start. If I wait a minute it will start and then shut down immediately. If I wait a few minutes it starts up again and then runs fine for a while and then the whole process repeats itself.
Is the motor overheating? I'm not doing a lot of cutting with it.
Thanks
Alex
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It could be, yes. More information would help, though: - is the motor open, or TEFC (totally enclosed fan-cooled)? - are your dado blades sharp? - how much wood are you trying to remove at once with the dados? - do you have the saw plugged directly into an outlet, or are you using an extension cord?
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Doug Miller (alphageek at milmac dot com)
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Hi,
I think it is TEFC but I'll check tonight. The blade is sharp and I'm removing about 1/8-1/4 at a time. Its plugging directly into a 20A outlet.
Thanks
Alex
On Jun 7, 9:28 am, snipped-for-privacy@milmac.com (Doug Miller) wrote:

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alex wrote:

...
Sounds like it -- the heavier load of the dado appears to be enough to trigger it. Try taking compressed air and blowing it out thoroughly, maybe if your lucky it's just not getting any ventilation from having gotten full of sawdust over the years.
If it's old, of course it's possible it's got a more serious problem. Could be capacitor, could be winding, might even have a failing bearing that is a contributor as well.
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A 3/4 HP motor is pretty small to be trying to cut dados with and it most likely has a temperature cutout switch imbedded in the windings to shut it off if it runs too hot. Clean out the motor with compressed air. Then make several shallower cuts with your dado blade. A 6 inch dado blade will work better than an 8 or 10 inch blade on an under powered saw as it will require less power. These older under-powered saws will do the job but you have to be much more patient with them. I suffered with one for years, but made a lot of good projects with it.
You might also be better off cutting your dados with a router, at least until you can afford a better table saw.
Charley

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I had a 1 hp motor and it was pretty low on power, I would imagine with 25% less than that you are pushing the motor too hard with the dado set. Make shallower passes.
I would guess that since the motor is some what predictable and you have recognized a pattern that it has an internal thermal switch that is self resetting. The switch could also have that thermal protection.
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Sounds like a thermal overload is opening & shutting down the motor until it cools. Is your mag switch a conventional NEMA style motor starter with heaters? Sometimes these loosen slightly and the added resistance of a bad connection heats them enough to open the circuit, even though they are not being overloaded. It is also possible, perhaps more likely with a 3/4 hp motor, that it has built-in thermal protection. For safe use in a tablesaw this should be of the manual reset rather than automatic reset type. You don't mention having to reset anything, so more info would be helpful here. Next time the saw stops running feel the motor with your hand and see if it is overly hot. Warm is OK but generally it should not get so hot that you cannot leave your hand on it. Let us know what you find.
`
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alex wrote:

Correct. The thermal overload protection inside the motor is shutting it down to protect it from overheating. That's perfectly typical operation.
The protection may be "taxed" or ie have been activated so often that it's physically changed in its characteristics and no longer fires at the right temperature. From your post, it sounds like that might be possible.
Or, it might be doing what it's supposed to do.
3/4HP is a little small for a table saw IMO but then you didn't say what size blade you're spinning. If it's a 10" blade the motor is almost certainly not powerful enough for long loads.
Operating time also affects how hot things get. Ripping is usually a long process where the heat inthe motor rises constantly as it continues to be loaded. Eventually it reaches the point where the protector shuts the motor down. Most of those type motors aren't meant for long-time run operations under load. The plate most likely indicates temp or intermittant duty. Most are like that.
Make sure there is plenty of air movement around the motor. Be sure the openings aren't clogged with dust & debris or something isn't preventing air flow to/from them.
I once had a motor that I dropped a bolt into. Luckily it only hit the fan on the shaft and broke off a blade. I broke off an opposite blade to rebalance it until I could replace it, and it ran fine. But ... it wasn't capable of the previous loads I had been able to use it for. It balanced "OK" to all appearances, but just wasn't moving enough air anymore. New fan part for it and all went back to fine. I know one guy keeps a DC pipe on his motor to help it stay cool for ripping long boards, but those are dimensional 2x's and green (Amish sourced).
HTH Pop`
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