Bandsaw motor rebuild help please

[Superburban]

This worn shaft,



And this worn bearing,



Has allowed the rotor to contact this winding frame.



Resulting in a motor with no desire to go.

Even looks like the bearing on the working end is worn.



Just my 2 cents worth.

 

[lens42]

I tossed my 4x6 saw motor and got a 3-phase motor and VFD. I didn’t really need variable speed, but a 1/2 horse motor and VFD were about $150 bucks on eBay. Now my saw runs forever without breaking a sweat.


Sent from my iPhone using Tapatalk

 

[RobertB]

This worn shaft,

View attachment 307555

And this worn bearing,

View attachment 307556

Has allowed the rotor to contact this winding frame.

View attachment 307557

Resulting in a motor with no desire to go.

Even looks like the bearing on the working end is worn.

View attachment 307558

Just my 2 cents worth.

Shaft doesn't look worn to me, just has a few dings in it, as long as it's still snug in the bearing shouldn't be a problem.
I'm not sure how you can determine a ball bearing is bad by that photograph. If they don't feel bad they are probably fine.

If any of the above were the problem the motor would at least let out a hum and get warm very fast.

 

[Tinker2]

If you don't have any electrical test equipment, get yourself an inexpensive multimeter w/continuity.

https://www.electricalengineeringtoolbox.com/2015/12/how-to-test-and-check-single-phase.html
https://www.bing.com/videos/search?q=how+to+test+ac+motor+capacitor?&qpvt=how+to+test+ac+motor+capacitor?&FORM=VDRE
https://www.bing.com/videos/search?q=how+to+test+motor+winding?&qpvt=how+to+test+motor+winding?&FORM=VDRE

I recently bought a used 80 gal/5 HP air compressor for cheap. The prev owner said the motor just quit running. Didn't smoke; didn't smell; didn't spark; didn't hum. Just quit running. And the air pump wasn't siezed. He was pretty certain the motor would have to be replaced [$$$]. I wasn't so sure. Got it home. Did some online research. Checked the wiring w/ a multimeter. No shorts. All I found was a broken wire at the terminal to a capacitor. Fixed that and my $100 air compressor runs like new.

 

[Chris H]

Eureka! Thank you to all who posted! I certainly learned a good bit on this, and the information provided was helpful! The problem turned out to be the little breaker plate on the top cap of the motor (yeah, that's the technical term for it durnit!).

The shaft isn't really worn where the bearings are, just has some odd nicks on it, but they're not circumferential like from a lock up, and the bearings are okay. They have some small "bumps" in them, but you can only feel them turning the race by itself by hand, and are too small to notice when spinning the armature in the assembly. For this, I'm just going to let them run for now and see if any other issues pop up after I start using it to cut something tougher than air.

 

[RobertB]

Eureka! Thank you to all who posted! I certainly learned a good bit on this, and the information provided was helpful! The problem turned out to be the little breaker plate on the top cap of the motor (yeah, that's the technical term for it durnit!).

That is the contact portion of you centrifugal switch.

 

[Superburban]

The shaft isn't really worn where the bearings are, just has some odd nicks on it, but they're not circumferential like from a lock up, and the bearings are okay. They have some small "bumps" in them, but you can only feel them turning the race by itself by hand, and are too small to notice when spinning the armature in the assembly. For this, I'm just going to let them run for now and see if any other issues pop up after I start using it to cut something tougher than air.

Sorry, my bad. I do not recall seeing a shaft with a step. But I have repaired a couple that were worn and looked like that, due to frozen bearings.

 

[Chris H]

Sorry, my bad. I do not recall seeing a shaft with a step. But I have repaired a couple that were worn and looked like that, due to frozen bearings.

No worries at all! If I got mad every time an idea didn't work out, I'd stay pretty ****** at myself!

 

[Tim9]

I don’t want to insult OP.... but just to point out a common problem on these saws is the automatic cut off switch on the blade side of the saw on opposite end away from motor. Just a simple rocker switch which has a small metal bracket which pushes switch off after metal piece gets cut. I know my switch ended up broken after a move. Rocker broke totally off....MIA. JUST A NUB WAS LEFT.
Also...easy to temp hot wire a motor. And lots of YouTube videos on motors