Chuck question

[rockyrude]

I picked up a 6" three jaw chuck with a 1-3/4" thread, my lathe is 1-1/2, can I just bore it out for an insert and rethread the insert?

 

[benmychree]

That would be a thin insert, I don't think it would work; are the chucks made with a removable backplate?, if so, a new backplate would be the way to go.

 

[rockyrude]

The back plate is 4-1/2 diameter, can't seem to find one that size. I am thinking boring to 2"which I think would be enough " meat"

 

[benmychree]

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The back plate is 4-1/2 diameter, can't seem to find one that size. I am thinking boring to 2"which I think would be enough " meat"
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I would buy a rough cast or semi finished backplate and machine it to fit. Or I might make a pattern and have some cast by a iron foundry.

 

[pacifica]

I picked up a 6" three jaw chuck with a 1-3/4" thread, my lathe is 1-1/2, can I just bore it out for an insert and rethread the insert?

might be easier to find a 6" 3 jaw with 1 1/2 thread

 

[mksj]

The question would be what size back plate can be used on it, if it requires a 4 1/2" then get a semi-finished 5 or 6" and turn it down to the spec you need and drill/tap for the chuck. Using a double threaded adapter/spacer is most likely going to introduce a lot worse TIR at the end of the day.

5" 1-1/2"-8 Threaded Back Plates

<!-- <ul><li>Thread size: 1-1/2 - 8<br /></li><li>Diameter A: 5.079"</li><li>B: .709"</li><li>C: .826"</li><li>D: 2.677</li></ul> -->

www.shars.com

6" 1-1/2" x 8 TPI Back Plate

<h1>SB1388 6" 1-1/2" x 8 TPI Back Plate</h1> <p>For lathes with 1-1/2” x 8” and 2-1/4” x 8” threaded spindles, the SB1388 6" Blank Plates allow you to make modifications to fit your lathe chuck.</p> <p>Simply mount to your lathe, true up the face and turn down the ledge to fit your chuck.</p>...

www.grizzly.com