Unisaw Motor Action

[jeff friedman]

I recently bought an older (70s) Unisaw. I immediately had to replace the blade shaft since the threads were messed up. Previous owner would add washers as spacers in from the blade because you could not spin the nut all the way to the blade. While i was replacing this, i went ahead and replaced the bearings and the 3 belts. When i run the blade and stop the motor i almost feels like there is a break that stops the blade quickly. I am not sure if this is just the way it is supposed to behave or if i have over tensioned the belt or have done something else wrong. I have attached a video. Let me know if this is normal action. it also sounds and feels like there is excessive vibration during start-up, never mind that ringing after the blade stops
I recently bought an older (70s) Unisaw. I immediately had to replace the blade shaft since the threads were messed up. Previous owner would add washers as spacers in from the blade because you could not spin the nut all the way to the blade. While i was replacing this, i went ahead and replaced the bearings and the 3 belts. When i run the blade and stop the motor i almost feels like there is a break that stops the blade quickly. I am not sure if this is just the way it is supposed to behave or if i have over tensioned the belt or have done something else wrong. I have attached a video. Let me know if this is normal action. it also sounds and feels like there is excessive vibration during start-up, never mind that ringing after the blade stops


https://www.youtube.com/watch?v=uEwZDIdA-BA

[Matt Day]

Can’t see the video. Uni’s are pretty straightforward. Unless there’s a brake installed it should take about 5-7 seconds to stop I’d guess.

[jeff friedman]

Trying pasting that link into your browser:
https://youtu.be/JQGOxMBLK3o

[Matt Day]

0-2. “The video is private.”

[Phil Gaudio]

Simple answer: no that is not normal.

[Bill Dufour]

Take off the belts and stop/start the motor by itself to see if it still happens.
Bill D

[jeff friedman]

ok, try now and tell me your thoughts:
https://youtu.be/JQGOxMBLK3o

[Bruce King]

Still says private.
unplug it and rotate blade by hand to see what it feels like. Should be smooth.

[jeff friedman]

Ok public now. I guess I am questioning how freely the blade should rotate. It’s connected by three belts to the motor at some tension greater than zero and should put some resistance on the motor. But is this excessive.

[Phil Gaudio]

Its odd that I can still here the motor winding down after the blade stops spinning: hope this is just a glitch with the video?

[Bruce King]

The arbor plate nearest the belts that the blade goes up against may be rubbing the arbor bracket. Try again with no blade, if it makes noise let it run for 15 seconds then unplug and feel for heat on that blade plate.

[jeff friedman]

I will take the table off tomorrow, remove the belts, and see how to motor sounds without anything attached. I will also ensure the arbor plate is positioned out far enough not to be rubbing. I think the whining or ringing you hear is a vibration in the blade itself ( super cheap) that continues after the motor has stopped. I am hopeful I have a good saw.

[Bruce King]

I would do some checking and looking with the blade off before going to all that trouble.

[Travis Conner]

I don't think it's supposed to stop that quick.

[Randall J Cox]

I have a 220v 3hp unisaw, bought in prob 97. Belts not tight, pretty loose actually compared to most belts on other machines. Have never adjusted them, all seems to work fine, never has ever stopped or slowed down no matter what i cut with it. Guess my only point here is don't go crazy on getting belts really tight. Especially with three belts. Probably takes 10-15 seconds to stop when turned off. This thing has been bullet proof since I bought it. Dead on and no issues whatsoever.... Randy

[Bruce King]

I agree, with three belts the weight of the motor is adequate force to tighten.

[jeff friedman]

OK I post two more videos. One showing the free rotation of the blade with the belts removed. And the other showing the power on of the motor without belts. Tell me what you think.

https://youtu.be/lev7Sf1JQGc

[jeff friedman]

https://youtu.be/XHhRBF-0dcg

[jeff friedman]

I found this article on motors that appear to be “braking” :https://www.finewoodworking.com/forum/noisy-brake-in-tablesaw-motor

[Bruce King]

Sounds bad, that triple pulley is just connected to the motor shaft so problem is in the motor, probably bearings. I would try to lube them if the saw has been sitting around unused.

After second look it might be the fan.

[jeff friedman]

No comments?

[Bruce King]

Pretty much waiting on you to take the end off the motor to see if anything is obvious.
Did you verify it’s getting the correct voltage?