Mashed shaft key

Carol Reed

In Memoriam
Coolidge, AZ
Got a little time and broke the old saw down further. Got to the arbor shaft assembly.

The belt pulley shaft end has a half moon key that is really mashed into its slot. I can't get it out. Being half moon shaped there is no exposed slot in the shaft end to drive in a wedge to pop it loose. It is slightly proud of the shaft and I've tried the bigger hammer approach but it ain't giving up. I don't want to damage the shaft. Any ideas?

Not a great picture, but...

shaft key.jpg

I want to get the shaft out of the housing to replace the stiff old bearings.

Follow up on the galled shaft.

galled shaft.jpg

Looks like what my friend thought. There is no play with a blade on it. What's the procedure here?
Diagonal side cutters, pinch the key and rock it out... you can drill and tap for a set screw or bolt etc and force it out...use a dremel tool with a cut off wheel and cut a slot down the length of the key and then pinch it to lift it out, this works great but use all safety devices on or heat<being careful not to damage the shaft...cold punch and a hammer...Hmmm what else git after it Gal :thumb:

Edit: since you say it's a half-moon type, secure the shaft with a block of wood and try tapping{lightly} on one end of the key which will hopefully raise the other along with breaking it's hold.
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PB Blaster, nothing else is as good, soak it in PB Blaster then do some tapping and banging like Ken suggested.

Heat, well if you heat up the shaft and make it expand it might pop loose but for that to really work you would have to keep the key cool, not easily done.

The halfmoon or Woodruff keys are usually softer metal than the shafts, IIRC, so you can use a sharp center punch and punch a divot on say four spots, then drill into the key itself, this might let the key shrink in size a bit and it might come out.

Great chance to use a TIG welder, just zap the key with the TIG a bit and the key and only the key will heat up a lot, then put some water on it to cool quickly (only the key will get hot, you won't heat up the shaft so the quick cooling will NOT damage the shaft) the big swings in temp should make it break loose.

Another approach is to put the shaft in the vice, bearing end down, close the vice until it is almost gripping the shaft, the one end of the key should now rest on the top of the inboard vice jaw, then with a sharp cold chisel tap on the top of the key, the part than is NOT sitting on the vice, this too could break the key loose. I'd wrap the shaft with a couple of layers of tape just to keep from damaging it if the key comes loose suddenly and the shaft drops.

Keep at it, it will come loose!
If the pb blaster fails heat up the whole thing a smidge and then hit the key with a shot of the stuff from a computer air blaster thing (hold the can upside down to get the liquid to shoot out. That should cause the key to contract and hopefully loosen it enough you can work it loose

Looks like the thread file ought to do it for the arbor. Nice that it wasn't too bad!
This is one of those "just thinking out loud (sortof)" things. If you have a bearing puller, maybe put the clamshell/splitter relatively tight on the shaft, snug it up against the key, and pull?
My surefire way of getting stuck woodruff keys out of a shaft is to take the shaft over to the bench vise, open the metal jaws just wide enough for the width of the key, lay the shaft down on top of the slighly opened jaws with the key set down between the jaws, tighten the vise on the sides of the key, then rock the shaft slowly up and down to lift it off of the key (held firmly in the vise jaws). It's about the best leverage you'll get, and doesn't present much of a chance at damaging the shaft.
Woodruff keys are cheap to replace if yours gets damaged.
Good luck with it