How to remove pulley key?

Hi, I couldn't find a small engines newsgroup so here I am. I just installed a pulley on a 5.5 HP Honda engine for a cement mixer. The drive shaft and pulley are "keyed" so they gave me a 3/16 square rod from which to cut the key.

I cut the key, slid on the pulley, pounded the key in with a hammer, and cut the key flush with the end of the shaft. There is no setscrew.

Then it occured to me: If I ever wanted to remove the pulley how in the hell would I remove that key? It's a really tight fit. How is this done normally?

--zeb

PS. There is maybe 1" clearence between the engine and the backside of the pulley.

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snipped-for-privacy@hotmail.com wrote:

You pull off the pulley and then pull the key straight out.

BTW those keys are normally filed to a nice fit. However, pounding yours in won't have hurt anything but it may have malformed the keyseat slot slightly.

GWE

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Grant Erwin wrote:

Geez, I though that was the whole point of the key-- to keep the pulley on. You didn't say how you would pull off the pulley, with some kind of hydraulic machine?

--zeb

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The job of the key is to prevent the pulley from rotating relative to the shaft. It is not the job of the key to prevent the pulley from being pulled off the shaft.

i

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The key prevents rotation, the pulley is secured to the shaft on a taper. To remove, a puller is used. Arms grip the pulley and a bolt is turned against the shaft.

Tapers are a common way to secure something to on in a shaft. An other common example would be how a drill chuck is fit into a lathe or a drill press.

--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.
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snipped-for-privacy@hotmail.com wrote:

On a small motor, pulleys are usually secured with a set screw, maybe two. The key just keeps the pulley from freewheeling on the shaft.

GWE

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snipped-for-privacy@hotmail.com wrote:

Also, you pull the pulleys with a puller. I bought a dirt cheap import set many years ago and they have served me well. Here's an example: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber@965

Grant

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Grant Erwin wrote:

Hey, thanks for the link.

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On 16 Nov 2006 07:33:59 -0800, snipped-for-privacy@hotmail.com wrote:

CRINGE!!!!!!!!!!!!!!!!!

Someday in the future..someone is gonna have a really bad day....

Gunner, machine tool mechanic

Rule #35 "That which does not kill you, has made a huge tactical error"

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Gunner wrote:

So how should I have done it?

The tech at the parts place said the keys are made to be tight, they will not just slide in by hand --unless he was handing me a bunch of BS. I just checked and the key rod is marked as 3/16" and the published specs of the key ways are each 3/16 x 3/32. I hand ground a slight taper on the end of the key just to get it started. Did I do something wrong?

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On 16 Nov 2006 09:31:26 -0800, snipped-for-privacy@hotmail.com wrote:

A "properly fitted" (YMMV) key, should be a snug slip fit in both the pulley and the shaft.

Lay a piece of 400 grit sand paper on a flat surface, and making figure 8s, gently "lap" the key until its a snug slip fit into the shaft.

Then slide on the pulley on. A bit of Dychem or even a quick wipe down with a magic marker will show if/where things are dragging.

Be sure to keep your orientation. Side to side fit in both the shaft and the pulley is far more important than top to bottom. Particularly if the set screw bears on the key. A key is to prevent rotary play between the shaft and the pulley. If play develops..it will deform the key and the key will either shear in half, or worse..beat the shit out of the loose part..either the shaft or the pulley.

I repaired a Clausing Variable speed drill press a couple weeks ago. The keyway in the pulley was perfect..however the keyway in the shaft extended 1/3 the way around the shaft. The key..looked like a fossilized turd.

The only thing I could do was pull the rotor, remachine a new keyway halfway around the shaft, fit up a new key (slip fit as described above) and put it back into service.

When you hammered the key in..you probably swoll up the keyway in the pulley, if it were softer than the shaft, or visa versa. You are probably ok, in your application, its not going to get used 24/7 in a production machine shop. But its really bad form to use a hammer for assembly <G>

Unless you are a carpenter or a black smith...

Gunner

Rule #35 "That which does not kill you, has made a huge tactical error"

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That's detailed reply. Thanks.

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You will find that admitting ignorance and then carefully considering replies around here will cause the most cranky old farts to soften and give you an explanation. I suspect that they just want to know you are listening to what they are saying. If they think you think you know it all, you are doomed.

--
Roger Shoaf
If you are not part of the solution, you are not dissolved in the solvent.
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