Removing pulley from a motor spindle

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I agree that "the final" option is cutting off the pulley. Carefully drilling the hub next to the keyway - radially out from the keyway ( maybe only 1 or 2 x 1/8" holes?) - after drilling the key with as large a hole as to think safe before risking damage to the shaft - should release stress in the hub when the hub cracks open. Thus enabling it to be pulled-off the undamaged shaft. If cast, the pulley will be scrap. It otherwise you may be able to recover it by welding (depends on your skill) with some finish machining. But I understand you want to fit a different pulley?
The pulley is cast so may well end up as scrap - but yes, my intention is to replace the pulley for a different diameter one. For the next few days I will just be adding penetrating oil in, to try and ensure rust is broken up as much as possible, then I will tackle attempting to remove it following all the helpful advice given here!
However you manage to do it, you need to preserve the shaft and bearings.
A damaged shaft may make the motor unusable for fitting the new pulley, a damaged bearing (e.g. from a too-heavy bash with a hammer) - can indicate the shock that has been enough to cause hidden damage to the windings. You won't find out "till it blows!".
The other thing that may loosen a tapered gib key is to drive the pulley onto the shaft a little further. That will loosen the taper on the key. Of course, grub screw will need removed first. If all else fails, a left hand drill bit is my go-to. You run the drill in reverse and the LH drill bit often grabs the screw and unscrews it as you drill.
Whatever you do, do not put a regular claw puller on there with the claws gripping the outer perimeter of the thin pulley flange. It will crack lumps out of the pulley almost every time. Heed earlier advice about drilling and tapping holes into the pulley hub area to pull on, or putting a split bearing puller plate behind the pulley and attache your puller to that.
Just to back up what K2 said - I once used a sliding hammer on a stubborn pulley and although I succeeded, I found out that the stator laminations had shifted apart and torn into the windings - I pushed the stator back together with a hydraulic press and rewound the motor. The point is that impact damage can occur throughout whatever it is you are working on. The stator was not "in the line of fire" and was damaged by inertial shock loads - Newton's second law an'all.

Also those tapered gib type keys are typically used on drives for things like crushers, vibrators, grizzlies and such - applications where most other methods fail - again the point is they are not meant to work loose under the most arduous of conditions and are therefore always going to be an SOB to remove.
More so after years of corrosion.

Regards, Ken I
Lots of great advice here about how to go about removing your pulley from the motor. I would like to say there are different penetrating oils and some do work better than others. I prefer Kroil with PB Blaster being a close second choice. I have heard of a homemade version of a solvent and transmission fluid but don't know the exact specifics. I think I read on the internet somewhere there was a test that showed which ones penetrated than the others and I seem to remember that the homemade one was the best, though you can't believe everything you read on the internet.

The screw has to come out first or be removed, probably hardened so be careful with what drill bit you're using.
If you can solidly support the opposite side of the shaft of the grub crew so hitting the screw with a correct size straight hex shaft to jar it slightly while trying to turn it with vise grips or pliers might help. Similar to the old Impact driver that you hit with a hammer and it turned a bit with each hit. The shaft needs to be supported so the shock is not transmitted to the bearings of the motor.

Speaking of vise grip pliers, is there enough of the key hanging from the end to grip? If so, can you grip it and use a pry bar of sorts to get in and pry it out? Maybe a slide hammer attached to vise grips to pull it out?

Hopefully this makes sense and good luck.


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