Cleaning up worn 3 jaw lathe chuck ?? - rec.crafts.metalworking

Message from discussion Cleaning up worn 3 jaw lathe chuck ??

e...@whidbey.com

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More options Jul 24, 8:28 pm

Newsgroups: rec.crafts.metalworking

From: e...@whidbey.com

Date: Thu, 24 Jul 2008 15:28:28 GMT

Local: Thurs, Jul 24 2008 8:28 pm

Subject: Re: Cleaning up worn 3 jaw lathe chuck ??

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On Thu, 24 Jul 2008 20:00:26 +0800, "Den" <Inva...@someemail.com>
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.

Greetings Den,
First take apart and thoroughly clean then lube and reassmble the
chuck. Make sure then scroll is clean and the scroll sectors in the
jaws are clean. To fix the inside jaws you will need to grip a spider
that loads the jaws the same way as gripping a part on the OD. If the
jaws are one piece then the only place you can really grip a spider is
at the bottom of the jaws. Once the jaws are closed on the spider with
normal clamping force the jaws can be ground. For the outside of the
jaws use a ring and expand the jaws against the ring. Now the jaws
will run true but only in the places where they were ground. Runout in
other positions may or may not run true depending on the wear.
Cheers,
Eric

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