Jet belt sander- motor gets way too hot, motor doesn't get hot... why?

did you check the top bearing in the sander?
edit: also did you check the belt tension? maybe too tight?
 
woodchucker said:
did you check the top bearing in the sander?
edit: also did you check the belt tension? maybe too tight?
Click to expand...
I was using the wire wheel when it was acting up, so I removed the belt to free up some power. The fault continued, so that eliminated that possibility. I just have to come to terms with tearing into it even though I have more important projects to work on right now. I sure don't want to be without it while I'm doing fab and auto resto work. I'll post what I find on Friday or Saturday. Thanks to all for the assists.
 
pontiac428 said:
I was using the wire wheel when it was acting up, so I removed the belt to free up some power. The fault continued, so that eliminated that possibility. I just have to come to terms with tearing into it even though I have more important projects to work on right now. I sure don't want to be without it while I'm doing fab and auto resto work. I'll post what I find on Friday or Saturday. Thanks to all for the assists.
Click to expand...
I have a Jet grinder. I have the same issue of getting SUPER hot. I can't touch it when I have been using it a long time. I did stop it from climbing non-stop, but it still gets too hot.
 
pontiac428 said:
I was using the wire wheel when it was acting up, so I removed the belt to free up some power. The fault continued, so that eliminated that possibility. I just have to come to terms with tearing into it even though I have more important projects to work on right now. I sure don't want to be without it while I'm doing fab and auto resto work. I'll post what I find on Friday or Saturday. Thanks to all for the assists.
Click to expand...
Projects begat projects :)
Tis the way of things.
 
If it has start and run winding there is likely a centrifugal switch to transfer to the run winding at speed. The trouble is likely there.
 
Okay, I've been going gangbusters on a project so I have only pulled the sander and moved it to a better spot to take it apart. Sorry to bring up a topic then not follow through. I would really like to have the wire wheel right now! Anyway, if I don't get to it this week, it will be two weeks before I can. I have a Tier 2 State pistol match this weekend to focus on, but after that I can see what is what. Thanks to all for the feedback so far.
 
I finally got the belt sander torn down (mostly because I really need my wire wheel). I accessed the capacitor and found two pairs of wires twisted together and weakly clamped by the pinch bolts on the power switch. That's not good, but probably a different problem. I ordered a new cap since I'm already here.

PXL_20220831_185537368.jpg

Next, I got busy tearing down the motor. First thing that happened after I got the bell ends off is the centrifugal switch springs hit the floor and rolled away. That's probably getting closer to the root cause, no? Luckily, I found my springs and got the switch reassembled and tuned up. The other end of the shaft was a melted plastic mess, and what was left of the fan impeller was not recognizable:

PXL_20220831_205342328.jpg
The bearings were also trashed. I bought some Timken replacements with 2zz shields, hopefully those hold up for another 30 years. I got hold of Jet's service department, and they sent me a pdf of the correct manual for this tool. The dude said he can source the parts, just to let him know what I needed. Fan impellers from Jet's current 1/2 hp grinder motor are around $15, so here's to hoping I don't choke on the price quote.
 
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