On Sun, 19 May 2013 15:53:42 -0500, Tim Wescott
wrote:

On Sun, 19 May 2013 10:27:01 -0500, 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?

This is an interesting thread, 'cuz I learned from someplace (which I
cannot now remember!) that you just don't trust 3-jaw chucks to not have
runout -- if you want precision without runout you use a collet set, or
you use a 4-jaw chuck and spend the time to dial it in each time you
mount the piece.

By "run true" do you mean that a round piece has runout, or that it's
tilted?


Years ago an apprentice was taught that a three jawed chuck was never
expected to hold a work piece exactly "true" and one always started
with a slightly oversized piece of stock and when the O.D. was turned
to size it was, of course, "true".

The standard rule was that one never removed the work piece from the
chuck until it was finished. One could however, usually remove the
entire chuck with work piece from the lathe and reinstall it without
problems

--
Cheers,

John B.