On my last carve,
and a couple of times before,
the pulley on the top of the Z-motor (it’s a NEMA 23) has come loose,
allowing the motor shaft to spin while the belt stays more less in one place.
this is bad as you lose Z and start to cut at incorrect depths… like this:
so that sucked.
When this last happened I observed that one of the two nuts holding the pulley in place on the motor shaft was spinning freely when I tried to tighten it down: it would not ‘lock’ when completely tightened and I inferred from this that the threads inside the pulley were stripped and the pulley would need to be replaced.
so I bought a new pulley and today I am today trying to place it on the machine.
I have loosened the Z-MOTOR so I can rock the belt off of it.
I removed the belt carefully, so as not to score it.
I then took out the little nuts holding the pulley in place.
Finally, I reach over to pluck the old pulley off of the motor shaft so I could replace it with a new one.
Because nothing is ever simple, you can guess what happened next:
now the pulley is frozen on the shaft and no matter what I do I cannot get it off.
Have tried a variety of things involving leverage and force in the right directions,
but cannot get it off.
scared to force too much as I may damage the motor, shaft, etc and with them my hopes and dreams.
I have managed to score the old pulley and knock the top lip off of it, so I guess I am committed at this point to completing the activity but not entirely sure how?
Also trying with this new information to form a new theory of why the pulley was coming loose.
Wondering if the motor was heating the shaft enough (it was > 5 hours of continuous use) for the different materials to expand differentially and cause the pulley to slide free?
if true, would suggest maybe I should get a torch and heat the pulley (?) to get it off, but wonder if driving heat down the shaft would damage the motor. Also worried about creating the smell of melted wiring.
Any thoughts and advice on this will be gratefully considered.
Happy Independence Day