On Jul 24, 6:00*am, "Den" wrote:
I looking for some advice on how to improve my lathes 3 jaw chuck.

Without going out to the workshop to measure it, it's about 7" or 8"
diameter. The jaws are worn *and when small diameter work is fitted it is a
off centre by ~0.020". Looking at the jaws I can see where they are flogged
out a little, particulary the outermost 10mm or so.

I occaisionally stick a drill bit or endmill cutter in the chuck and clamp
some work in a vertical mounted vice on the cross slide. I dont know if
gripping the hardened tools has contributed to the jaw wear.

What's the best way to clean them up. The chuck jaws allow external/outside
edge clamping - can I wind the jaws out and fit a ring and then run a boring
bar across the inside clamping surfaces of the jaws as someone here
mentioned a week or so back?

Cheers.

I did this, once, cleaned out the crud in the scroll, relubed, then
made a ring and and a cross-slide rig for a die grinder to grind out
the divots in the jaws. If you do this, you can get it pretty good,
at that one spot. If you've got hardened jaws, some form of grinding
may be your only way of cleaning up the faces.

Best bet is to learn how to use a 4-jaw chuck, 99% of what I do is
done with a 4-jaw. It's only when I need to chuck up hex stock that
the 3-jaw gets put back on the machine. It really doesn't take that
long to chuck up something to within a half-thou using a good
indicator.

Stan