Noisy Brake in Tablesaw Motor
measure2wicecut1ns
| Posted in Power Tools and Machinery on
I picked up a used Rockwell tablesaw. Although I tested it prior to purchasing, I now notice that the brake is really loud when the motor spins down. Although it is a bit noisy, the motor seems to run smoothly and it cuts wood just fine while under power, but it would be nice to have a motor that doesn’t make a loud clunking noise after it is turned off. If I bought a new motor, or had it repaired, I’d probably be at a price point close to a brand new tablesaw. Is there a fix for this that it not too complicated for a mildly mechanically-retarded person such as myself?
Replies
"M2" Are you sure it has a brake? The noise is probably the starting switch. It cuts out after the motor gets up to speed and drops back in as the motor slows. It could be malfunctioning or you are just not used to the noise. Some motors are a bit noisier then others when everything is OK If you feel comfortable pulling the rear bell off of the motor you might see the problem. Just make sure it is unloaded, ugh unplugged I mean. There are centrifugical weights and springs, these can get out of wack and are sometimes repairable and/or parts could be available. Yogi
Yogi, it sounds like that might be the problem. It only makes the noise as the motor starts to spin down. I guess one other solution would be to sell the saw and try to get what I just paid for it. Thank you for your input, everyone.
It would help if you post the motor manufacturer - if it's a Delta or Rockwell badged motor, the manufacturer will be shown in small print at the bottom of the motor's nameplate. What kind of saw is it?
As others have said, some motors are rather noisy when the centrifugal switch closes on shutdown, but it could be perfectly normal. Such a noise is subjective, and impossible to expain so someone else - one man's 'noisy' is another's 'normal'.
Take the belt(s) off, and listen to it run. If it runs quietly at speed, and only makes some noise when down to about half-speed on shutdown, I wouldn't worry about it, and certainly wouldn't get rid of a good saw because of it.
Since you thought it had a brake, I'm guessing it's a Baldor. They supplied many of Delta's motors during the 60's and/or 70's, including during the Rockwell Int. peace-sign logo era, if memory serves.Be seeing you...
TK, You are correct. Its a Baldor, mounted on a Rockwell 34-410. It makes one loud "clunk" as it starts to spin down, then it spins down a little more quickly. That's why I thought it was a brake, but then someone else on here told me tablesaw motors don't have brakes. The saw works fine under power, it vibrates some, but alot less than the tablesaw I just replaced. I'd hate to get rid of it. It was a hassle getting it to my house, and I'd hate to go through all of that again.
Well, if it makes you feel better, I have an assortment of Baldor single-phase motors laying around here, from 1200 to 3600 rpm, made over a wide range of decades, and every single one of them makes a noticeable scraping sound as they spin down, though what I call noticeable would be difficult to define. All of them also slow down rapidly once the centrifugal switch closes, due to regeneration, which makes the windings sort of fight each other, in a manner of speaking.
There is a way to make them stop regenerating, and Delta even sold a low-voltage control at one time that could be configured to do that, but it's nothing to worry about. Baldor is the only brand of single-phase motor I've ever run across that does that, by the way. But there is definitely no brake in there, and if the motor runs smoothly, I would use the saw in good health.
If your motor is TEFC (totally-enclosed, fan-cooled), so much the better. Even if it's from the Rockwell International era (peace-sign logo on blue field), when Rockwell was working hard to cut costs, I think the saw is likely better made than many (most?) of the current crop of import contractor saws, and that's also true for the motor. In my humble opinion, at least.Be seeing you...
TKanzler.
Actually, these motors do have a "brake." It's not a mechanical brake. It's electrical.
The "regeneration" phase is the application of opposing magnetic fields, bringing the motor to a stop very quickly vs "freewheeling" down to a stop by just removing power, as in most other single phase motors.
Rich
If you are talking about a standard type of contractor saw with a standard motor they don't have a brake. It might be the fan rattling around.
I would check the sheaves(Pulleys) to be sure they are on the shaft tight.
Work Safe, Count to 10 when your done for the day !!
Bruce S.
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