PDA

View Full Version : Talking of keystock....



Timleech
03-21-2006, 01:30 PM
I had a real struggle a couple of weeks ago to pull a hardened gear off its shaft. It was supposed to be a press fit, but it came OK for about 1/8" & then took me half a day to get it the the remaining 4". There was an excrescence at the inner end of the keyway, I thought someone must have bodged a worn keyway with some sort of plastic metal. No, it turned out in the end, so far as I could deduce, that the keyway in the hardened gear was a bit tight & whoever last assembled it didn't check the fit, and the key had in effect extruded out at the end. There was a 3/16" step in the end of the key, where it had been pushed over the end of the shaft keyway, and a similar step at the outer end of the key from where I had been pulling it off.

Incidentally the manual for the gearbox (1930's) talks about 'feather keys', I'd seen the term before but not paid too much attention. This time I decided to look it up. It took a while to find a definition, but I discovered that originally a feather key was one secured (screwed) to the shaft such as might be used in sliding clutches etc. This wasn't of that type, and now the term seems to be used for any parallel key.

Tim

J Tiers
03-21-2006, 01:34 PM
Yeah, I've seen it used for any key either secured to the bore, as in a feed pickoff from a leadscrew, or secured to the shaft.

Noew it seems to be any longer than usual key, especially one that is long to allow for an alinement, as with a pulley. Been guilty of that usage myself.

As for tight ones..... I had a heck of a time getting one cutter off the arbor..... the key was awful tight...

Then when I did, I found the cutter had sheared halfway through it. That expanded it to fill the arbor keyway, and jammed it pretty good in the cutter also. Didn't want to turn back and come off, didn't want to slide out intact.



[This message has been edited by J Tiers (edited 03-21-2006).]