How to save this pulley.

[FTlatheworks]

I had a custom clutch I bought for a project. It came with a 1/2 inch v pulley. I decided I would turn my own 5/8 pulley. I should have done it between centers, but I dint have an arbor, arbor press, or lathe dogs that will go around 2 inch stock.

I had a couple of mess ups, but the part is salvageable. I unchucked 2 times and had to do all kinds of wacky things to make sure I was still concentric. My problem now is, I need to be able to bore a 1.372 size bore, with a small 1 inch lip, then another 1.372 bore. This all has to be done from the same side. What’s the best way?

I can take the part off and finagle back to concentricity, but I think boring it from where it’s at is best.

 

[MrWhoopee]

Assuming that 1.372 bore is close tolerance, I would bore the thru dia and counterbore then turn the part around. Not that hard to indicate back in and MUCH easier to measure the counterbore.

 

[extropic]

I don't know what you mean by "small 1 inch lip".

I suspect you should have started with the bores, then turn the outside.

A sketch would help get better answers.

 

[toprecyler]

You should be able to make your first bore. Then if understand you correctly, you want a small section that is 1” diameter, then back to 1.372” diameter. You can do this with a grooving type boring bar.

But it gets harder to hold tolerance because the bar has to be small enough, with the tool stickout far enough to make the 1.372” diameter bore, all going thru the 1” diameter hole, and has to stick out as far as needed to go thru the pulley.

The boring bar will flex a lot, will need to take light cuts and several spring passes.

Hardest part will be measuring the bore with spring calipers, that might have to have modified bent tips to be able to measure 1.372” thru the 1” hole.

Or you can turn the pulley around and chuck on the flange. I have a selection of wear bands from hydraulic cylinders that I use to help hold thin parts in chucks, that are hard to hold with the vee cuts in the chuck jaws. You may be able to wrap a piece of thin shim stock around the pulley to help itself hood in the chuck jaws.


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[jwmay]

Step one seems to be: Put the four jaw chuck on. A three jaw is not the tool for finagling. You can…but it’s much easier with a 4 jaw. Lacking that, I guess I’d make a one off collet to hold that pulley so you can flip it with good registration.

 

[Eddyde]

An expanding mandrel would work. You can turn down the diameter fit you bore, then flip the part around and mount it on the mandrel it will be concentric and you can then machine the second bore accurately.

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You can also make such mandrels fairly easily.

 

[FTlatheworks]

An expanding mandrel would work. You can turn down the diameter fit you bore, then flip the part around and mount it on the mandrel it will be concentric and you can then machine the second bore accurately.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

You can also make such mandrels fairly easily.

Good idea. Just like an arbor?

 

[FTlatheworks]

Step one seems to be: Put the four jaw chuck on. A three jaw is not the tool for finagling. You can…but it’s much easier with a 4 jaw. Lacking that, I guess I’d make a one off collet to hold that pulley so you can flip it with good registration.

I’ll try the four jaw tonight. There’s just not a lot of material to grab on the v pulley side.

 

[FTlatheworks]

Assuming that 1.372 bore is close tolerance, I would bore the thru dia and counterbore then turn the part around. Not that hard to indicate back in and MUCH easier to measure the counterbore.

I did bore the thru diameter for the 1 inch bore. Now I just need to make the 1.372.

I’m copying the part I’m holding, but with a 5/8 v

 

[Eddyde]

Good idea. Just like an arbor?

Yes, they expand by tightening the screw. If you turn them true or indicate them true in a 4 jaw, they are very accurate. You can also buy them in sets, they come in handy a lot for me.