Re: Further testing needed ...

"Snag"  wrote in message news:vcnitb$1p0o6$1@dont-email.me...
   I don't think this chuck has much wear . All the jaws look "new" but
that doesn't always mean much . I was told the original owner was into
woodworking , which doesn't necessarily require the precision needed for
metal working . By tightening all 3 pinions I have gotten it down to
average .004" , which is pretty close to my original equipment 5" chuck
. I can live with that ...
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I've considered using a bearing press disk set to measure the jaw inner face runout at several diameters, to see if it varied due to wear or errors in the scroll or was a constant error of the jaw faces, which might be corrected on a surface grinder. A 3-jaw will grip evenly if the disk isn't quite round.
For a 6-jaw that won't a stepped cone of plastic or a trued lawnmower blade balancer could have enough flex to allow all jaws to clamp tightly, then measure runout on the outer jaw surfaces and subtract their thicknesses, a job for a spreadsheet.
I haven't tried this because I have 5C collets for precise work, a Set-Tru, and lower cost 3 and 6 jaw chucks on 5C mounts that can be moved between lathe and mill without unclamping the workpiece. Since I design what I make some surface can usually be sized to fit a collet or mandrel for second operations or later mods.
It appears that tubing thin and flexible enough to need a 6-jaw is also flexible enough to fit a shaft despite jaw runout, for instance bearing spacer rings. I haven't yet had a job that would require fitted pie jaws or a pot collet.
jsw