Before you scrap that 3-jaw, take it apart and clean it meticulously
and then check the scroll's bore for looseness. I recently read an article
that claimed that scrolls wear in their central bore, and that the wear is
usually uniform, and that this wear can be taken up by one shim wrapped
around the ID of the scroll's bore. Clean it, blow it out, check the scroll
play as I described, and *then* measure the eccentricity. I had a 10" 3-jaw
that went from .020" to .004" by cleaning and shimming.

GWE

shedfull wrote:

Thanks to all who replied,

That chuck was, uh m TIGHT

Its off now, got the taper cleaned up and sorted the gap piece out.
I think that chuck hadn't been off for 20 years, (could explain the
unused F/plate, catch plate and little used 4 jaw ?)
The 3 jaw sc chuck was a mile out,
I was thinking of swappng it for the 4 jaw independant I have and
investigating the 3 jaw.

Many thanks again.