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Pulley / woodruff key question

cj133

Aluminum
Joined
May 8, 2014
Location
New Jersey USA
Hi all,

I've got what may be a silly question, or, maybe it's important. :confused:

I have a 3/4" steel shaft with a 3/16" woodruff key in it. I'm installing a cast iron 9" diameter V belt pulley on the shaft and the setscrew lands on the woodruff key.

I've only used normal square keys. Is a woodruff key ok with a set screw on it or is this asking for a failure?
Oddly enough this pulley only has the 1 setscrew also, not the typical 2.


Expected torque on shaft and key is roughly 60ftlbs @ 1400 rpm.
 
On the back of the key is the best place for a set/grub screw to press, it saves tha shaft from being buggered up.

Ideally, Woodruff keys are only used for location, not torque. But that rule seems to be ignored more often than not.
 
The only possible problem I see is if the set screw cocks the woodruff key and makes the pulley hard to remove. Why not drill and tap for a new set screw or mill the shaft for a flat key.
 
It doesn't matter how you do it, the life won't be long. 3/4" shaft isn't nearly large enough for a 16hp load.
 
I do it frequently, learned the practice from a very old machine shop. Your results are fine, or at least better if you spot drill where the set screw will land.

Has been my experience anyway.

Set screws set against the shaft are spawn of the Devil.........Bob
 
Setscrews belong over the key. Otherwise the key wants to roll in the seat. The roll is not a problem with a woodruff, they just want to break out the side of the shaft.
 








 
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