Question about 3/4hp Baldor motor

[Alex Shanku]

Last night my bandsaw, which has had no electrical problems to date, started making a loud "BRRMMMM" noise upon start up and the whole saw vibrated loudly. I shut it down immediately and tried again...same thing. The motor spins when this occurs, but stops almost immediately upon powering down. Not the gradual slowing that normally occurs. So today I removed it, checked the connections, opened the case and blew it out. Nothing looked out of the ordinary. Although, the ground from the cord connected to the grounding bolt on the motor was a tiny bit loose. I tightened and test it out. Spun great. No more problems. After about 5 minutes of usage today, the same problem occurred as I described above.

Any ideas?

Thanks guys,


Al

[Steve Clardy]

Older motor? Does it have oiler holes?
Bad bearing maybe?
After it quits, shuts down, remove the belt and see if it spins freely by hand.

[Mike Canaris]

You should run the motor with no load for aboot a minute to see if it still doing the same thing...so just remove the belt and see.Also turn the wheels by hand while the belt is off to see if everything is smooth.

[Cliff Rohrabacher]

R U sure its the motor??
Could be a slipping pully or bad bearing

[Pete Bradley]

Did you change something recently? New band or belt? As others have suggested, you need to do a process of elimination.
1. Slip off the belt and see if the motor runs smoothly and quietly (I suspect it will). A "tickatickaticka" sound just before it stops spinning is ok. A scraping or screeching sound indicates a bad bearing.
2. Turn the wheels by hand and see if the band binds or catches on something, and whether the wheels turn smoothly.
3. Check the guides, especially that the thrust bearings aren't too far back and the blocks aren't too close.
4. If you don't find a problem with 1-3, tension the band, check the tracking, attach the belt and start up the machine. If the problem disappears, it was probably tension-related.
5. Check for flutter, especially on the back side (the part of the band that goes up). If the band is a blur, you're fluttering.
6. Check to see if the belts are vibrating and/or whacking against a guard and the pulleys aren't wobbling.

Pete

[Alex Shanku]

OK guys, just got home. Thanks for the advice so far.

1) I havent changed/adjusted anything. It just "happened"

2) With or without the belt on, the same thing happens.

3) The saw / motor worked and sounded fine after I removed the motor. But problem returned again

4) Everything spins freely and smoothly.

5) Perhaps I never noticed this before, but when I switch the motor on, the lights dim a little.

6) I dont think the motor is that old, it looks very new and is very clean.

7) When rotating the motor's shaft by hand I notice no grinding/difficulty rotating.

[Jeff Horton]

I'm betting on a bad bearing once it get warm to hot.

[Alex Shanku]

Jeff, I would prefer to change them myself, providing this is the problem. Is this a difficult process? It looks like the bearing on the fan side of the motor is pressed onto the shaft. What would a motor repair shop charge?

[Steve Clardy]

Unless you have a press, bearing holder, etc, mission impossible usually.
Take it and get an estimate. Sometimes you may get a new motor for what it takes to repair one.

[Alex Shanku]

Steve, I will probably do that tomorrow.

Update:: I just went into the shop and turned it on, with blade tensioned and belt on. Loud noise and vibration occured. I took the motor's shaft and was able to push it in about 1/4 inch. Turned it on again, and worked a lot better, just slightly more vibration than normal.

BUT!! Normally the saw make a loud BRRMMM when the power is shut off. It spins for about 5 seconds and makes a rough stop. This time, it didnt do that and just spun smoothly until it stopped...

This sucks!! lol

Off to the motor shop tomorrow to see whats up. Thanks for all the help, and any ideas are greatly welcomed.