I have an old (15 yrs) Delta Super 10 table saw. Blade mounts on the motor shaft. Decent saw. But I have been having problems with it not starting properly When you flip the switch, it starts up, then starts vibrating badly, then shuts off. Does so even with no blade.
The circuit consists of a switch, start relay, run capacitor and start capacitor. A couple of years ago I replaced the capacitors when it was having problems, and it went back to normal ops. Now it’s doing it again. I don’t remembwer if I changed the relay.
Question: why do I need the relay and capacitors? It’s not a big motor. Why can’t I just go with the on-off switch and the motor?
Whenever you are asked if you can do a job, tell’em “Certainly, I can!” Then get busy and find out how to do it. T. Roosevelt
Replies
It need the capacitors because it is a single phase induction motor.
The caps are used to turn single phase power into 2 phase power. Typically they only have the single start cap, but some higher efficent motors (and I think to get more power per pound) also have a run cap.
When you say that it "shuts off" exactly what do you mean? Does it trip the overload?
I am think that this is more a mechanical problem. Broken mount, broken motor end cap. Bad bearings.
Could be the centrifical switch in the motor. Pull the motoer off and test it on the bench.
Dave
It sounds like it's overheating and the overtemp is cutting out, probably because the centrifugal switch isn't opening up, the relay's stuck, or one of the caps is shorted. In some cases there is no switch and the relay is time-delay or current-sensing.
A common fault is the centrifugal switch fails to disconnect the start coils once the RPMs come up the motor will overheat in a minute or two. Sometime faster. A quick and dirty way around this, if it works, is to give the motor a sharp bash or two. Best to use a block of wood and a hammer. No need to try to harelip the Pope swinging but don't be timid.
Often this will jar the contacts loose or otherwise free up the mechanism. No guarantee this 'repair will last but I have seen motors keep operating a long time after a 'correction'. A more detailed examination and repair can get things going sometimes. No loss if it doesn't. Other times it is best to, if you have a devil-may-care attitude, disconnect the start coils and 'flip' start the motor by hand.
The capacitor going bad or a shorted winding are also possible causes of this behavior.
Where is the centrifigual switch located? I don't mind using a little kinetic energy, but no point in applying it to the wrong end of the motor.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
the side away from the arbor IIRC.
blow it all out real good with an air hose too.
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
When a motor starts up "normally" you'll see a spark come from the area just as the motor gets up to speed. If you look inside the unit with the motor stopped you'll see a gizmo consisting of several pieces of stamped sheet metal surrounding the shaft on that end.
Try just giving it a whack first. The impact will often free stuff up enough to work. Even if it only works for a few cycles it tells you where to look. The contacts sticking or the mechanism binding after setting up, a bit of corrosion, for a time is pretty common. Removing the rust, cleaning contacts and a little lube can often get these beast running again.
Of course it still could be a bad capacitor or a wiring fault. Checking the motor for shorts or grounds to the case is quick and easy. A good motor shop can often rewind the motor for less than the cost of a new one. A good option for harder to replace units.
"Where is the centrifigual switch located?"
Ed,
As Sphere said, the non-shaft end. I've experienced the same problem from time to time. Open up the inspection cover at the end of the motor, and move the switch inward along the shaft in .020" increments till it works right. That should do the trick.
Jon
Gee thanks. My tape has black diamonds, but no decimals ... another tool to buy ...
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt