I am again asking a question re chuck jaws, my old Pratt chuck has som
wear in the jaws (slightly belled) I can grind them true again with toolpost grinder but are they completely hardened or case hardened? I case hardened i'd sooner not try as they wouldn't last too long havin ground the hard metal off. Davi
-- stereotyp
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Case hardened but it's quite thick. In any case it's not the end of the world if you grind through. I did on my 3 jaw to get it running right and it's made no difference to how well it works. Soft jaws are after all a very popular type of work holding system. If anything I think you get a higher coefficient of friction and better grip when the jaws are soft than hard.
I made a silly mistake in the setup when I tried to true my jaws many years ago and ended up taking a large amount off all of them, several times over in fact, before I got it right and then had to thin the sides again on a linisher so they could close down to a small diameter. If you just take a gnat's willy off the high ones you won't have the same problem. I'd like to think that with what I know now compared to back then when I was just starting out in machining I wouldn't be such a dick but we all learn by our mistakes.
Just out of interest, how will you tighten the jaws down on the scroll to achieve the bore that you will grind? How will you "flat" the jaw face to remove the radius?
Is it possible that the "belling" is due to wear on the jaw/chuck tenon which may vary over the clamp range?
I have just started monitoring this group and already notice some names from other groups that I post to. You all seem like a nice lot ;-)
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