Will this locating scheme work?

I want to locate a pulley on a shaft. The timing of the pulley is
critical. Once the pulley is located on the shaft the timing location
will be set. Then the pulley will need to come off and be replaced in
the exact position many times. I was thinking that maybe a tapered key
would would work. I would make a key with a large enough taper that it
wouldn't be self locking. I would be depending on the narrow faces of
the key to do the locating. Opinions? I welcome even critical ones.
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Snug-fitting keys are probably the most common way. Another common way is with a roll pin and a diametral hole through hub and shaft.
If you have an odd number of teeth on the pulley, and if you pinned it, I'd use a tapered pin and taper the hole so it only goes on one way. If the tooth count is even, it doesn't matter.
Reply to
Lloyd E. Sponenburgh
How accurate does the location have to be? I'm wondering if a standard taper bush and keyway would provide the location you require.
Reply to
David Billington
Is the location fussy enough that you feel you need the taper to remove all play? It oughta work, though kind of a pain to make.
If you can tolerate a minimal amount of play, what about a radial pin thru the shaft and a mating slot in the pulley's hub?
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If the torque requirement is modest, I suppose you could make the pin slightly larger than the slot and push the pulley against the pin with a threaded knob. That'd eliminate any play, but heavy torque would tend to cam the pin out of the slot.
Or the slot could be tapered slightly to accept the full dia of the pin, but provide some interference when it bottoms.
Reply to
Ned Simmons
Maybe use a standard taper-lock but instead of using the tapped holes = as-provided, drill and tap your own
Reply to
Woodruff key.
Broach the pulley's key slot on the centerline of a pulley step so it can go on either way. You could locate the pulley initially with a pointed setscrew to mark the position on the shaft. For fine adjustments later you could machine a custom offset or wider key from drill rod. I've made several stepped straight keys for non-matching pulley and shaft slot widths and had no problems with them.
Reply to
Jim Wilkins
Hey Eric,
How often is "many times"? Would a sliding fit on the shaft to mate with a fixed dog-clutch or something similar work?
Brian Lawson.
Reply to
Brian Lawson
I thought I was the only one to use that method.
Reply to
Your description is too vague for us to suggest several good possibilities. How much torque does the pulley withstand, how accurately must it be positioned, will it be readjusted later, can tools be used to remove it?
I'd consider mounting the pulley on a keyed bushing with a nut or snap ring to retain it, and then timing the bushing's position.
Here is a quick one-hand locking device:
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A safety-wired nut is pretty quick and simple, and less work to make.
Reply to
Jim Wilkins

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