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Drive Pulley has some play

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Boris Ludwig

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#1
The pulley on the motor shaft has a key way and a grub screw. The grub screw feels tight but over time the the pulley is able to rock on the shaft. It gets noisy and I have to loosen the screw and tighten it up again.

Is there anything I can put on the shaft and key to take up the slack between the pulley and shaft? Something that wont be a pain to disassemble when I need to make a change. Or should I get a new pulley?
 

Z2V

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#2
Have you thought about using shim stock? How much slack are you talking about? Does the key fit good and tight in the key ways? Just off the top of my head.
 

Boris Ludwig

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#3
Its only slight but enough to cause noise that bugs me. The key is tight on the shaft. It's the pulley that's a bit big. Slides on easily but no side play. It's just able to very slightly turn on the shaft. Key way in the pulley is just a tad big.
I haven't tried anything yet I just thought I'd ask first to save myself time.
 

markba633csi

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#5
You might try some removable Loctite (like 242) either on the setscrew or on the shaft itself, or both. Also, you might want to consider adding a second setscrew to the pulley if there is a suitable spot to drill and tap another hole. Sometimes putting two setscrews one on top of the other helps.
I had the same problem as you with my bandsaw motor pulley (no key, just a flat on the shaft) and adding a second setscrew on the next sheave worked for me.
Mark
 

whitmore

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#6
The pulley on the motor shaft has a key way and a grub screw. The grub screw feels tight but over time the the pulley is able to rock on the shaft.
I had such a problem, and the fix was to run a reamer down the pulley hole; it was slightly (out-of-round? conical?),
but after making it circular, the problem went away. No guarantees, but if you can't fit a shim in to tighten the
fit, it could be that the hole isn't round enough to achieve shaft contact.
 

BtoVin83

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#7
If the hub has enough material can you make your own version of a taper lock or QD hub?
 

chips&more

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#8
You might try some removable Loctite (like 242) either on the setscrew or on the shaft itself, or both. Also, you might want to consider adding a second setscrew to the pulley if there is a suitable spot to drill and tap another hole. Sometimes putting two setscrews one on top of the other helps.
I had the same problem as you with my bandsaw motor pulley (no key, just a flat on the shaft) and adding a second setscrew on the next sheave worked for me.
Mark
Hi Mark, you have the right manufacture but I think you want to try the 660 stuff. I used the Loctite shaft repair on a worn out table saw pulley/shaft and I was totally amazed!!!!!!! I could be wrong on the Loctite number? It was gray in color. I remember the instructions saying it was for a temporary fix until you got the replacement parts. But the stuff lasted for years and never failed. I will try and find the tube in my shop. And try looking up shaft repair products made by Loctite…Dave
 

markba633csi

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#9
242 is probably not the best choice but I've used it for all kinds of oddball repairs
It IS amazing stuff- how did we ever get by without it? :cool:
 

Cadillac

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#11
When you have a pulley mounted on a shaft with a key way. There should be two set screws. One directly over keyway to engage key to shaft. The other mostly is 90* from keyway. To lock pulley to shaft. If you put 180* from key it might want rock naturally because of the two pressure points. And red LocTite is always good insurance.
 

Boris Ludwig

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#13
I had such a problem, and the fix was to run a reamer down the pulley hole; it was slightly (out-of-round? conical?),
but after making it circular, the problem went away. No guarantees, but if you can't fit a shim in to tighten the
fit, it could be that the hole isn't round enough to achieve shaft contact.
The pulley hole is round but the key way in the pulley is I tad too wide so the pulley rotates on the shaft. When I just tighten it's ok but after a week or so it's back to noisy normal.
 

Boris Ludwig

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#14
When you have a pulley mounted on a shaft with a key way. There should be two set screws. One directly over keyway to engage key to shaft. The other mostly is 90* from keyway. To lock pulley to shaft. If you put 180* from key it might want rock naturally because of the two pressure points. And red LocTite is always good insurance.
In my case there is just one on top of the key.

The pulley rotation is only small but enough to be noisy and it probably increases wear which may mean eventual failure. Hey, I'm still new at this so I'm not sure.
 

dave_r_1

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#18
Maybe make a new key that wedges in the pulley a little closer, so it will have a little step between the where it goes in the motor shaft keyway and where it goes in the pulley keyway?
 

Cadillac

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#20
You won’t wanna keep running like that with a wobble. Eventually it’s gonna wear your motor shaft from rockin.
With all the things wrong with that pulley. Bore loose, keyway to big, only one setscrew. I would just make or buy a new one and stop pulling your hair out on this. That pulley should be easily sourced and really overall size can be changed for your speed request.
 

Boris Ludwig

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#21
You won’t wanna keep running like that with a wobble. Eventually it’s gonna wear your motor shaft from rockin.
With all the things wrong with that pulley. Bore loose, keyway to big, only one setscrew. I would just make or buy a new one and stop pulling your hair out on this. That pulley should be easily sourced and really overall size can be changed for your speed request.
You know it has no sideways play on the shaft just rotational as the key way in the pulley is a tad big so when the set screw comes loose as it does every month I pull out my hair.

But you're probably right, I probably ought to change it.
 

whitmore

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#23
You know it has no sideways play on the shaft just rotational as the key way in the pulley is a tad big so when the set screw comes loose as it does every month I pull out my hair.
There's an old variant of a key, a stepped key, that fits mismatched shaft/pulley keyways. It oughtn't
be impossible to make one, That'd be quicker than buying another pulley.

Another outlying possibility: could you put a blunt-point setscrew in, and maybe a bit of brass shim at its
tip, then maybe friction on the moving key wouldn't turn the setscrew (it's a bearing, kinda). At a
prior job, we had fits on a bunch of clamping screws that got loose in shipment: same thing,
minor slippage was enough to loosen our lockwashers as the truck went over a bump.
There's occasional torque during shipping jolts, like you're seeing when the pulley key
exercises its slack keyway...
 

francist

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#24
Stepped key is a great idea -- except I'm not seeing a matching key way in the shaft. In either of those shafts, actually. Could be a big part of the problem, it's just relying on the grub screw to limit rotation.

In the absence of a proper key way, at least put a flat on the shaft. Less opportunity for screw to wiggle back and forth.

-frank
 

whitmore

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#25
Stepped key is a great idea -- except I'm not seeing a matching key way in the shaft. In either of those shafts, actually. Could be a big part of the problem, it's just relying on the grub screw to limit rotation.
Ooh, good point; I assumed it was a simple key. There could be a Woodruff key, the shaft end
wouldn't show it. Don't think there's any tradition of W-key with a step, though.
Odd image shows up that might be something like that, here: <http://a.co/903nofJ> (or
the long form, <https://www.amazon.com/OES-Genuine-Camshaft-Woodruff-Mercedes-Benz/dp/B001G7EG4C> ).
 

francist

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#26
Agreed, could be a woodruff. Or even a stopped key way which wouldn't present from the end. However, I think either of those would be rare and unusual occurrence. Especially on something this small (as opposed to a hydraulic shaft or something).

I have cut in the occasional key way using a Dremel tool, but it's not a great way to do it and could easily make things worse.

-frank
 

Boris Ludwig

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#27
I'll take a few photos today with it pulled apart so you guys can see the key, keyway in the shaft and the pulley. I might make it all that much more clearer.
 

Boris Ludwig

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#28
20180526_111620.jpg

20180526_111656.jpg

Not sure this really shows much but I decided to put some brass shim between the key and the pulley keyway and its a bit tighter I hope it works. 20180526_111603.jpg
 
Last edited:

Boris Ludwig

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#29
If the hub has enough material can you make your own version of a taper lock or QD hub?
Sorry BtoVin, I missed this, now I'm going over this thread again in case I missed something. So I'm wondering what a QD hub is.
 

tq60

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#30
Google 2 part pulley hub and that should give an idea.

It consists of a hub that slides on shaft then pulley or body slide on.

2 screws pull it on and same screws used in different holes to remove.

Simple and elegant.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk
 
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