4 Jaw chuck wanted 12"-16"

I am in search of a 4 jaw chuck for my 17x80 Clausing lathe. I need a 4 JAW, I have a 3 jaw and a 6 jaw already. The 4 jaw that I got with the machine is...well.. weird. The chuck itself is a good chuck, made in England and all that jazz, the problem is that the chuck has a tapered thread socket for mounting and it is on an adapter plate. I think the adapter plate was modified by the "gentleman" that owned the machine (did I say owned?..sorry, I meant abused) the machine before I got it. The chuck is anything but straight to the spindle, and I have tried to take the chuck/plate assy apart before to try to get it to run properly. That didn't work and I am tired of trying to make this work, I am worried that running it at the RPM range I run it at is/will cause issues with the bearings.


So, I need a chuck at least 12" in diam but no bigger than 16", preferably with a D1-8 camlock or a plain back that will accept an adapter. The lathe spindle has a though bore of 3-1/8" so something close to that bore or bigger. Let me know what you have and what you are asking.

Can you mount the backplate without the chuck mounted and face it true.

If your chuck has any kind of Recessed hole in the back you can turn a step on the back plate to register with the hole in the chuck.

Make sure the temperature of the backplate and chuck are the same.

When I did mine the faceplate was hotter then the chuck so it gave a sloppy fit when cooled down.

Other then that, your looking for a INDEPENDENT 4 jaw chuck right, not a 4 jaw scroll chuck?

Edit: I see your chuck has a taper thread now, so your right that makes things very complicated.

So your threaded taper backplate is probably off center while the cam loc is centered.

Yep that’s a pain

Hey Homebrew, Yeah I tried to face the adapter plate with it in the camlocks I did everything I can possibly think to try. I really think the old man I bought this machine from cobbled together some material and made himself an adapter. It is not concentric with the centerline of the spindle so it's got some wobble to it, especially when I am up around 495 RPMs and above. I just want to get a independent 4 jaw and replace the damn thing, I am not going to put anymore time into it at this point. I tried more than once to make it work and I think it is beyond buying fixing, it is more of the buy a new adapter type of thing. I have other D1-8 cam lock adapter plates made for plain back chucks, I think it would be easier and cheaper to find a chuck than to mess with this convoluted mess.