"Steve" wrote in message
om...
"Martin Whybrow" wrote in message
...
"Steve" wrote in message
m...

I've got the same problem with my 4" 3 jaw (Crown) chuck, it runs true
on
the spindle but a precision ground 1" rod chucked in it runs out between
.002" and .020". I dismantled the chuck; the scroll wouldn't budge at
first,
but I used a plastic drift through the jaw slots to knock it down ; you
have
to do this gently moving around the 3 slots as you go so as not to skew
it
as it is a precise fit in the body. Once I had the scroll out, I
refitted
the jaws and found that I had .0015" of lift in the no. 1 jaw which
explained the poor repeatability. I don't know where to get spares for
this
chuck, so it's destined for the rubbish bin eventually.
Martin.

What do you mean by "Lift"? Thanks, Steve

Sorry, that's the best description I could come up with at the time. What I
meant was play at 90 degrees to the chuck body face; imagine the chuck
laying on a bench on its backplate, then the play meant the jaw could lift
upwards.
Martin.