Had an idea the other day. Uh oh Anyway, since a lot of what I do on the lathe involves chucking slightly irregular squarish pieces of plastic to turn up a roundness to rechuck with to further turn the piece to make a part (did that make any sense) I could really use a chuck where opposing jaws can be adjusted independently of the other opposing jaws. Each pair needs to work like a scroll chuck, in other words they slide in and out in unison as you turn a ring or something.

So, a chuck like this would have two separate adjustments, one for one pair of jaws, and another for the other pair. Opposing jaws do not ajdust independently as in a typical four jaw.

Is something like this made? Or will I have to design and build it myself- and any ideas for a design?

One thing I'm considering is to make it so it mounts in the three jaw. That way I can leave the three jaw mounted, then just clamp this 'adapter' into it when needed. They will both be used together, one after the other, so I don't really want to remove the three jaw and mount this thing each time. Three equally spaced holes in the back of it will allow it to be held firmly enough, and it won't need to be a precision device since all I'm doing is mounting somewhat irregular square or rectangular pieces of varying sizes into it to turn a proper stub so they can then be turned using the three jaw.

I doubt there is such a device, so the real question is how to I arrange to crank the jaws in and out as independent pairs?