Bill Rubenstein wrote:
I don't like cole jaws and such because... Even when the blank is dry,
the rim is never going to be 100% because of the release of tension in
the blank as wood is removed.

Unless you are looking for an absolutely concentric fixing, which
generally isn't necessary, I can't say I have ever found rim distortion
to be a real problem when using cole jaws.


That said, the best way of driving a reversed blank (IMHO) is jam chuck
it with a chuck made so that the driving force is applied pretty close
to the bottom of the bowl.

I'm gonna be pedantic about semantics here, and say that what you
describe is not a jam chuck, or at least it is contrary to my
understanding of the term.

I have always considered a jam chuck to be a piece of scrap wood turned
to exactly the right size such that a small bowl (or box etc) can be
jammed onto it and held securely in place without tailstock support. The
jam chuck may grip either inside or outside the turning. If the fit is a
little sloppy, a paper towel may be used between the jam chuck and the
turning.



--
Derek Andrews, woodturner

http://www.seafoamwoodturning.com
http://chipshop.blogspot.com - a blog for my customers
http://www.seafoamwoodturning.com/TheToolrest/ - a blog for woodturners