Author Topic: keyless pulley on a keyed shaft  (Read 1533 times)

Offline hartek451

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keyless pulley on a keyed shaft
« on: August 07, 2016, 09:16:29 PM »
I find myself replacing the motor on my 15yo drill press.   It has the old d-type shaft, where it is just flatted for most of the length.   The step pulley just has a set screw to secure it.
Of course, I could not find a new motor with that style shaft.  Everything uses a keyway.  I have looked into replacing the pulley as well, one with a keyway already broached, but the existing pulley has a 1.5" tall..  boss?  I am not sure of the term.  It looks like a shaft collar welded to the bottom of the pulley.  The setscrew is in the collar.  I have not been able to find a new pulley with anything near that height base.
So, I am looking for thoughts on how to mate these two parts.  I think I have the following choices..
1) ignore the shaft keyway, and just file a flat on the other side of the shaft and secure the pulley using the set screw.
2) find a key that just fills the keyway on the shaft, and use that as the flat for the set screw.
3) get a new pulley, and a shaft collar the right height, line up the keyways, and weld it on using a level of accuracy I don't have anymore :(
4) buy a broaching tool and bushing and cut a keyway in the existing pulley.. I think the problem with this is that the pulley is 3.5" high.  that is a long way to try to broach.  I have heard of a blind broach?  not sure if that is what it sounds like.  Plus cost-wise it isn't worth investing much more money in it..
5) send it out to a shop?  same cost issue..

In case it matters, 5/8 shaft, 1hp 1800rpm motor, 4 step pulley, 3 pulley gearing..
tnx..

inthesticks

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Re: keyless pulley on a keyed shaft
« Reply #1 on: August 07, 2016, 10:15:45 PM »
Line up your pullies to run true and snug down on the set screw in alignement with the keyway on the motor shaft if the keyway slot is larger in diameter than the set screw you can tighten it there using the bottom of the keyway as your flat. If the set screw is larger tighten just enough to mark the location, remove pulley, drill one size larger than the set screw to the bottom of the keyway and reinstall the pulley. Tighten set screw in drilled hole this will prevent damage to the set screw threads and keep work to a minimum on the motor shaft

Cheers
CB

Offline PekkaNF

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Re: keyless pulley on a keyed shaft
« Reply #2 on: August 08, 2016, 01:38:11 AM »
That is a big motor and some torque to be transmitied.

I could consider the set screw into key way approach...does a dog point set screw end fits into key way well?

Another way could be to find an componenet with a keyway and bore the boss to accomdate it. Can you do a taperlock mount and does it fits?
http://simplybearings.co.uk/shop/Engineering-Parts-Taper-Lock-Bushes-Imperial-Taper-Lock-Bushes/c4713_4743_5252/p552373/1008-5/8-Taperlock-Bush-with-5/8-inch-Bore/product_info.html

There are some low profile tapered sleeves, but they are intented plain shaft, bit like H205 with OD cylindrical.

Pekka


Offline Pete.

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Re: keyless pulley on a keyed shaft
« Reply #3 on: August 08, 2016, 01:59:55 AM »
I take it the pulley has a round hole, not a D-shaped hole since this is much harder to create.

In your position I would swap the set screws for dog point set screws and just screw them into the keyway. It's been fine all this time driving on the set screws so there's no reason it should not still be fine on a new motor.

If that option isn't viable I would simply file the shaft to match the old one.

Online mattinker

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Re: keyless pulley on a keyed shaft
« Reply #4 on: August 08, 2016, 03:16:47 AM »
Please post a photo or a drawing, it's difficult to see where your problem is without it!

Regards, Ma.tthew

Offline chipenter

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Re: keyless pulley on a keyed shaft
« Reply #5 on: August 08, 2016, 03:26:01 AM »
My milling machine has a 1hp motor with two 6mm set screws at 90 degrees and no keyway, not had any problems sins I put the second screw in , it worked loose with just one .
Jeff

Offline Will_D

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Re: keyless pulley on a keyed shaft
« Reply #6 on: August 09, 2016, 04:13:28 AM »
I have just received a brand new Crompton 0.55 kW motor for my ML7 upgrade to 3-phase.

It has a 19 mm spindle with a long 6mm key.

I can't just bore out the old motor pulley (as in I will have the pulley in the chuck and not on the motor :doh:)

No problem to make a new pulley but how do I remove the key? I dont really want to slot it by hand with the carriage.

It appears to be glued in place. I know I could grind it off but hey its a new motor!

My intention was to use two M8 grubs turned down to 6mm at the ends to engage the keyway.

Do they really glue in keys these days or does it just need a bit more persuassion?
Engineer and Chemist to the NHC.ie
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Offline John Stevenson

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Re: keyless pulley on a keyed shaft
« Reply #7 on: August 09, 2016, 04:22:33 AM »
Grab the end of the key with a pair of side cut pliers parallel to the shaft and lever up.
John Stevenson

Offline Will_D

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Re: keyless pulley on a keyed shaft
« Reply #8 on: August 09, 2016, 09:22:59 AM »
Thanks John for the info.

Its like pulling teeth - get the right tool and itrs easy.

Was a struggle but its out!
Engineer and Chemist to the NHC.ie
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