What's new
What's new

Loose pulley on motor shaft.

jklawton

Plastic
Joined
Oct 20, 2011
Location
Rochester, NY, USA
Is there any reasonable way to secure a pulley on a keyed shaft where both have been worn leaving a largest gap of about 0.035 inches. This is an old Powermatic table saw, 2 Hp motor and 3-belt sheave. The cast iron sheave is worn more than the motor shaft but is not available as a replacement part. I am currently considering turning down the motor shaft enough to get a consistent diameter (max wear is ~0.015"), then converting to a poly-V belt drive with new pulleys on the motor and arbor. New motor pulley will have to be purchased unbored or bored out to match reduced motor shaft. I suspect that this is the best option, but wondered if there was some other reasonable option that I am not aware of being a mostly self-taught home shop machinist. I was even thinking about something like pouring low-melting temp metal or Stycast in the gap. Would this be long-lasting and strong enough. How would one ensure concentricity...
I bought this saw new in 1977 and this is the first trouble I've had with it so can't complain too much. Thanks for any discussion. Jim
 
Pull the motor rotor and turn down to a consistent size....bore and bush the pulley down to the motor shaft size.
Obviously scotch key the bush ( bush being a press fit to pulley) to the pulley and rekey the internal to suit the motor shaft.
put two grubscrews in it one over the key and one at 90 degrees to the key that should stop it coming loose again when you tighten them.

The best option is to make a new motor shaft and bring back to the nominal size but may not be needed. later if something happens you have all good sizes but its going one step further and has added expense.
Welding up the shaft is not advisable as it can crack in the heat effected zone...
 
sometime in a situation like this, turning a worn shaft or whatever down a bit will allow it to finish at a standard mm size, where there may be standard mm bore sprockets or sheaves available. I have done this before in a pinch. It allows you to purchase off the shelf items.

Just a thought!

Stuart
 
I had a massively slogged out key and worn shaft/pully on a lathe. Turned down the shaft between centers and put a QD or whatever taper lock pully on the shaft. Better than new.
 
I'd turn down the motor shaft and bore & bush the pulley, if you have the equipment and ability to do that. If dealing with the pulley is too much trouble, then investing in a new pulley is well worth the modest cost.

As a pro woodworker, I prefer the first approach tho, good skills to have and maintain for the time there is no other choice. Has saved my ass multiple times!
 
TIG weld the shaft up and turn down 1/16" oversize. Bore original pulley to match and cut a new keyway.

I've often wished I knew how to weld for this and other situations. Is this a relatively easy thing to do, or does it require years of training and experience? I think I know the answer, but just thought I'd ask.
 
I have a 6 HP compressor motor that the shaft had worn and rusted bad. As I needed it back running ASAP, I thought a temporary repair would work until I could get another motor. So cleaned and roughed up the shaft and then JB weld. After JB weld was hard I turned it in the lathe.

I was hoping it would last a few days but three years later the JB weld repair is still working perfect.
 
Last edited:
I had a 6 HP compressor motor that the shaft had worn and rusted bad. As I needed it back running ASAP, I thought a temporary repair would work until I could get another motor. So cleaned and roughed up the shaft and then JB weld. After JB weld was hard I turned it in the lathe.

I was hoping it would last a few days but three years later the JB weld repair is still working perfect.

You do realize it's gonna give up the ghost after bragging on it.
 
You do realize it's gonna give up the ghost after bragging on it.

Yes my bragging is gonna make it fail! Except for the fact that the new motor is about 20 feet away from the repaired one so won't fail as long as I have the new motor. If I ever get rid of the new motor, the repaired one will die about 15 minutes later. Maybe if I keep a picture of the new motor on the wall it will also work the same as actually having it?
 
The OP should be able to turn the motor shaft ,then taper bore the pulley,and make a matching taper bush,with a split to include the keyway......taller key ,drive in the bush ,and the whole assembly will be solid as a rock forever.Done this many times,never a fail......but is it hard to remove if a bearing should fail?.....Replace the motor bearings at the same time,before installing the taper setup.
 
to Have you looked at McMaster-Carr? They have a wide variety of repair sleeves for sealing, as well as collars, keyed collars, bushings, etc. that you could probably turn down to make the repair.
 
Bushing a pulley with a key is a total PITA. TIG welding takes practice, but it's infinitely valuable in these kinds of situations. I've salvaged grooved shafts cut by hard seals, filled and recut wallowed and broken out keyways, rebuilt broken or chewed up gear teeth (soft gears, not hardened transmission gears), etc... one of those things very much worth the effort, and especially with modern low cost hobby grade inverter machines.
 
I once repaired a 1/2" shaft double ended buffing motor that had been either filed or attacked with an angle grinder to something close to 3/8". It was not at all round and had a fair amount of taper to it. The entire motor was placed between centers on the lathe and each end was turned to even them up. I then made bushings which were slipped over the shafts and silver soldered in place with care being taken not to let the heat migrate into the bearing area of the motor. The motor was then again place between centers and trued to to the 1/2" diameter.
 








 
Back
Top