Ignoramus17710 wrote:

I am trying to finish up some unfinished business with my Clausing
6913 lathe. This is my question #2. I have a three jaw chuck on it,
and while the outside of the chuck is relatively true (as seen with a
dial indicator), the parts held in the chuck run anything but
true. From previous discussions and my searches, I could try to
regrind or re-cut the jaws, right? And if so, which way is better? Can
I do it with a carbide insert and auto feed?

You put a toolpost grinder, die grinder, Dremel or whatever you
have on the toolpost. You can use rings and pins or putty or
rubber bands to pull the jaws outward against the scroll, just
as it would be when gripping a part. Then you use the carriage
to run the grinder in and out across the jaws. I usually do this
a few passes with the carriage handwheel, then start the lathe
running and make a few passes with the power feed. You then
disassemble the chuck to remove the grit that has sprayed all
over the insides. Protect the lathe bed with wet towels (the
water helps trap the flying grit.) We paper towels on cardboard
work well, too.

This fixes bell-mouthing, ie. excessive wear at the tips of the
jaws. The bell-mouthing allows work to wobble in the jaws
while turning, and you get out-of-round work, generally with 3 lobes.
If the scroll is damaged or not constrained to center by the chuck
body, regrinding the jaws will not help. You may be able to
insert a rolled brass shim to constrain the scroll to the
chuck center.

I suppose you can do it with a carbide inset, but I've always
ground them.

Jon