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champion 10-inch chuck adapter

brassjacket

Plastic
Joined
Apr 21, 2019
My newly acquired champion 10" has a 1.25"-8tpi spindle nose. As near as I can tell there's a slight taper to the threads. I bought a 1.25" chuck backplate on amazon, thinking I could just spin it on, but it only goes on a few turns and stops.

Before I go down the do-it-yourself rabbit hole by trying to modify the backplate....
Is there any place I can get a 1.25"-8tpi adapter that will allow me to use the more modern chucks out on the market?
should I try getting or making a bushing to go from 1.25" to 1.5"? would that bushing be too thin?

on the one hand I'm new to this and not afraid to dive in and learn the hard way, but on the other hand it's best to get guidance from someone that knows what they are doing.
 
Are you sure about that thread? I can find reference to 1.5x8 and 1 7/16x12 but nothing for 1.25x8??

EDIT- is this Champion Machine of Cinti,OH or Champion Blower and Forge of Lancaster,PA???
 
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this is the one from Cincinnati, OH. yeah it's an oddball. I'm guessing some customization was done on it somewhere in its lifetime. I've attached pics.
champion.jpg


spindle.jpg
 
If you have a chuck that fits the spindle now, just chuck up the new back plate and pick up the treads and open them up some. After you take a pass or two, unscrew the old chuck with the new plate still attached and try the plate on the spindle and repeat until the new plate fits the spindle.
 
If you have a chuck that fits the spindle now, just chuck up the new back plate and pick up the treads and open them up some. After you take a pass or two, unscrew the old chuck with the new plate still attached and try the plate on the spindle and repeat until the new plate fits the spindle.


OK, I'll give it a try, carefully. Thanks so much for your input and advice.
 
I find it hard to believe that the thread is tapered. It may be that you just have one or two tight spots on
the thread that need attention with a thread file. I would examine the threads carefully with a good light
and a magnifying glass before I started cutting them on the lathe. Sometimes you only have to remove a
small amount of material to make the thread too loose...
 
Lots of old American lathes have a slightly tapered thread on the spindle nose, so that the tooling tightens up as its screwed on. I don't believe that the corresponding back plate threads are usually tapered, though.

Andy
 
The threads can be a little loose and it wont hurt anything. The register on the spindle gives you the center and the shoulder on the spindle keeps the chuck square.
 








 
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