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I have a Delta 36-650 table saw that's about 10 years old. Just recently the reset button started kicking off the motor. The blade is sharp. I've blown out the dust from the motor. There are no signs that the motor is hot---no smell or noticeable heat. Suggestions appreciated.
When does it happen? When cutting wood only?
Possibly the Bearings going bad or a failing Capacitor?
Only happens when cutting wood----no change in sound----arbor turns freely and smoothly without the belt. I was also thinking capacitor. There are two on the top of the motor.
You didn't mention it but, has anything changed in the electrical service? A longer cord, some other device on the same circuit leg? Just tossing ideas out there.
It sounds like the run capacitor may be bad and the motor isn't spinning up fast enough to trip the centrifugal switch to turn off the start windings. Any motor shop can check them.Quote:
Originally Posted by Tim Passmore
Thanks guys for all of your insight.
On my Grizzly I had the centrifugal switch get saw dust build up , which was causing the capasator to burn up.
I had some good photo bucket photo's of the switch , which of course are now hard to post . But I bet if you've been blowing out the motor , and it's similar to my Grizzly you really are NOT blowing out those contacts.
You need to remove the cover on the end of the motor , which will allow you to really get to the centrifugal switch.
I really suggest you pull that sort of fake cover , so you can blow out the switch.
My switch was sticking , so it ruined the capasator twice.
If there's no oil leaking out of the capacitor cover , the centrifugal switch could be the problem.
Thanks-------neither capacitor shows any damage to the naked eye. I did take off the end cover when I blew out the motor, however I think I will repeat that. Could it be the brushes?
Quote:
Originally Posted by Tim Passmore
An induction motor such as the one on your saw doesn't have brushes, although there are electrical contacts that are opened and closed by the centrifugal switch when the motor is started and stopped. The centrifugal switch can become caked with dust or the contacts corroded from arcing. This would be unusual but not out of the question for a 10-year-old saw that sees typical hobbyist usage. Getting access to it requires partial disassembly of the motor, beyond simply removing the shroud on the end that's held on by a few screws.
I would still be thoroughly investigating the capacitors. There isn't necessarily physical evidence that one of them has failed. Disconnect each one from the motor, ensure it's discharged, and test it with a multimeter on the ohmmeter setting. A good capacitor would show zero ohms to begin with, followed by a rise toward infinity.
If both capacitors indicate good, it's time to check the C-switch and/or the thermal reset switch.
Tim,
A motor that size in that saw won't have brushes, but if it is a single phase motor it will have a centrifugal start switch in the non shaft end cover. Check the switch contacts to see if they are burned or possibly stuck together. You can clean up the contacts by dragging a folded piece of 150 grit sandpaper (emery cloth of similar grit works better) folded so as to clean both contacts at the same time. Several passes between the contacts should be sufficient. Also check the springs and flyweight assembly on the end of the motor shaft. They move a plastic collar toward the shaft end as the motor spins up. This collar pushes on the switch that you just cleaned, to open the switch contacts and disconnect the starting capacitor and the start winding. What can happen is that the shaft gets dirty or rusty where this plastic collar needs to slide, preventing it from sliding. You can clean that area of the shaft with the sandpaper and then wipe a very thin layer of light weight oil on this area of the shaft. You don't want to leave any drips behind. just a thin coat, or it will fly off as the motor spins. Since you have the motor out and apart, I would replace both capacitors (in the cylindrical bumps on the side of the motor - be sure to replace with the same physical size as well as electrical rating). They aren't that expensive and you will have peace of mind if you change both. They last about 10 years on the average, so the one that isn't bad now, will likely fail soon. Grainger, an electric motor repair shop, or similar places are possible sources for them. Take the old ones with you to match them up. Again, they need to be the same mechanical size as well as electrical size.
If it is a 3 phase motor, you have likely lost one phase from the power source to the motor. Dirty contacts in the motor starter contactor (the relay in the big electrical box on the side of the saw) is the most likely problem. Each of the 3 sets of contacts need to be in good shape and making good electrical connection when the contactor operates. These can also be cleaned with sandpaper. Also closely inspect the wiring connections in this box, the motor, and the power cord for any evidence of damage and make a correction, if you find anything.
Charley
Quote:
Originally Posted by Tim Passmore
There's the outer cover and a inner cover on my saw that has to be removed .