Couple of comments, but I have to admit I did not read all 98 replies so I apologize in advance.
Most old 3 Jaw chucks are still pretty good.? My original 5" Atlas chuck just had bell shaped jaws from wear and I ground the jaws in a few hours with a small router.? That included making a wooden router mount and blocks to pre-load the chuck jaws.? It was not hard and the results were extremely good.? For a bunch of different diameters I tested the runout was about 0.003" or less which is pretty much all you can expect from a typical 3-jaw chuck.? I bought a new Shars 6" chuck with removable jaws and I only use it when I have to.? I still prefer the 5" chuck.
Don't expect to remove and remount anything in a 3-jaw chuck without checking it carefully with an indicator unless you can live with the error.? Maybe you have the magic touch but I don't.? If I need to do this I use a collet if I can.
Mounting a 3-jaw chuck in a 4-jaw chuck might make the 3-jaw perfect but probably only at one diameter.? Also it puts you further from the head-stock and you're starting with a pretty big overhung load.? (If no one answered the stub spindle question, it's a short threaded shaft that matches the lathe's spindle that is long enough to screw into the 3-jaw chuck and still long enough to mount in your 4-jaw chuck.?? Of course if your 4-jaw chuck is big enough you could just mount the 3-jaw chuck body in the jaws of the 4-jaw.)
When I am done cutting a thread I clean it up in the lathe with a stainless steel wire brush.? It works wonders for getting rid of the small imperfections.? For a right-hand thread I generally run the lathe in reverse so the brush feeds itself off the thread,?? I do this on aluminum too with a soft stainless steel brush.? For a big thread you can clean it up with a triangular file if you have to.
That's it.? Take it or leave it.
?
Jim
