Thread: Pulley Modification

Hi Bob,

What about a standard taper bushing?

Regards
Ray

Hi Bob,

What you are about to attempt is a common practice. I would look up a limit of fit chart and make the bush a light press in fit though.
Then it can be scotch keyed for peace of mind.
Do you need to broach a new keyway?

Your 1"/25mm should be fine.
I wouldnt worry about using LocTite,I would give a .001/.0015 interferance on the bore to bush.
I would Scotch Dowel it with either a Selock pin (roll pin,spring pin) or dowel.
The pulley would need to be Heated and Shrunk on your bush.
If you were going to Broach the Keyway after installing the Bush I would be inclined to make the Bore around 1 1/2" 38mm,this will allow a bit more meat to be incontact with the bottom of the Arbor press when Broaching.
I would also be inclined to Finish the Bore in the Bush after it has been installed in the Pully.

Thank you for the advice Tankstand, Ray And Pipeclay.

My rebore of 1" is looking overly optimistic, I measured the diameter at the bottom of the pulley groove and I have 1.300". I'll have another look tomorrow.

Rather than a bush made from cast iron , what about 1214? Still a shrink fit and Scotch keyed.

ive done something very similar for my mates drill press. it had a straight key for positive drive.
after pressing the plug in i marked out the position of the key way and drilled it. with a slightly smaller drill than the width of the key way. then drilled and bored the hole out to required size and then
filled the keyway square. it worked spot on. i used loctight strong bearing retainer on the pulley bush before pressing. it in. hope that makes sense.

I bored out the cast iron pulley to 0.930", a comfortable compromise, and made a sleeve from 1214 and heeded Pipeclay's advice by making it longer to ensure trouble-free broaching.

I pressed the 0.0015" oversized sleeve into the pulley after heating the pulley and freezing the sleeve. Even then I had to finish the pressing in my vise because I could not exert enough pressure with the arbor press.

I then finish bored the sleeve and broached the 3/16" wide keyway. I had to make up a guide for the keyway broach. I have a selection of smallish Dumont broaches and it's funny that each time I've used them, I've had to make another guide. None of the guides are a standard size except for this latest one.

After extending the tapped grubscrew hole, I fitted the pulley on the motor shaft.

I have not fitted a Scotch key. There is not a lot of metal either side of the junction between the sleeve and the small pulley groove. At the most, I reckon I could only fit a 1/8" dowel pin.

Do I go ahead and install the pin and if so, in what position in relation to the keyway?

Bob.

For what you are using it for the interference would probably be enough to hold the bush without the pin,but if you wish to use a pin the location really dosent matter.

Did you by any chance recheck your bore prior to broaching?

Is it only a 1 tonne arbor press?

Couldnt you fit a M4 grub screw from the side of the large pully and only go halfway through?

Came up good Bob, I always get a good felling getting a press fit right the first time
If you have a grub screw running through that will be plenty to keep it their.

Dave

Hi Bob,

If it's a tight press fit, then I suspect the belt would slip long before the bushing slips.

Nice job.

Regards
Ray

I agree that there is very little chance of slippage but to add my 2 cents worth drill and tap suitable holes centered on the join between sleeve and pulley on the big pulley end and fit grub screws secured with loctite. Common practice to have 4 grub scews holding a pulley on a centre boss to enable replacement, size change etc.

Dean

Thanks for the responses, fellas.

Pipeclay, when I initially turned up the sleeve I left the bore undersize, on your advice, and after pressing it in place, bored it out to 5/8''. I carefully positioned the pulley in a 4 jaw and checked that the runout on both the face of the pulley and the bottom of the vee groove was no more than a few tenths, prior to boring.

My arbor press is a nice one ton Reeve 51P. What didn't help me was that the thing was sitting on the shed floor during the pressing operation. A bit shabby!
I used to have it rigidly clamped to the the table of an old Elliott Progress pedestal drill. I chucked the drill press out to make room for my Swiss mill. I did clamp the arbor press to my wooden bench for the broaching operation.

The idea of a couple of socket set screws is appealing, and easy.

Bob.

I found a pair of 3/16''W x 1/2'' screws. I drilled and tapped the fat side of the pulley. Put a small dab of Loctite 262 on the threads, screwed 'em home and that's it, finished.

Bob.

Wait, is that a speck of grime I see? You're slipping Bob. Have to lift your game.