Amazing Servo

[ozzie34231]

I was running a mill program yesterday witha slow feed and a very slow Z axis move, (spiral hole). I've had the Z axis servo get hot while doing this kind of move in the past, but I kind of forgot about it.
After running a while I smelled something, looked up and the servo was smoking. I shut down and blew compessed air on it for a while, then left the job for a bit.
After I returned I noticed the motor had gotten so hot it crinkled all its paint and the belt had started to melt at its edge. I powered up to see how bad things were, and it ran. I reprogrammed to do the job differently and ran for a half hour, finnishing the job. Nearly every time the motor reversed there was an ugly noise. I figured I'd fried a bearing.
I took it apart this morning. ALL EIGHT MAGNETS HAD COME LOOSE FROM THE HOUSING! As far as I can see everything is okay except that the encoder disc is warped. That servo did the job with floating magnets and a bent encoder disc!
Fortunately I have a twin motor and I'm back running with it.
Now a question.
I'd like to see if I can fix it. I'm thinking I'll JB Weld the mags in place.
My question is; how should the magnets be oriented. I assume they all should be aligned; all south pointing one way, north the other. Is that correct?
They are two rows of four.
All comments appreciated.
Ozzie

[Zappautomation]

The magnets are most likely de magnetized or partially de magnetized.
It is unlikely you will get the same performance from the motor when you assemble it again.
If you have four magnets, they should be N S N S if you have two they should be N S

Originally Posted by ozzie34231 I was running a mill program yesterday witha slow feed and a very slow Z axis move, (spiral hole). I've had the Z axis servo get hot while doing this kind of move in the past, but I kind of forgot about it. After running a while I smelled something, looked up and the servo was smoking. I shut down and blew compessed air on it for a while, then left the job for a bit. After I returned I noticed the motor had gotten so hot it crinkled all its paint and the belt had started to melt at its edge. I powered up to see how bad things were, and it ran. I reprogrammed to do the job differently and ran for a half hour, finnishing the job. Nearly every time the motor reversed there was an ugly noise. I figured I'd fried a bearing. I took it apart this morning. ALL EIGHT MAGNETS HAD COME LOOSE FROM THE HOUSING! As far as I can see everything is okay except that the encoder disc is warped. That servo did the job with floating magnets and a bent encoder disc! Fortunately I have a twin motor and I'm back running with it. Now a question. I'd like to see if I can fix it. I'm thinking I'll JB Weld the mags in place. My question is; how should the magnets be oriented. I assume they all should be aligned; all south pointing one way, north the other. Is that correct? They are two rows of four. All comments appreciated. Ozzie