George
You have some good answers here. I often turn a hollow form or a vase that
will not be held by my chuck to turn off the base. On the other hand I
seldom use a chuck but that is not germane to this discussion. I would in
your case attach a piece of wood to a face plate and face it off. Then turn
a tenon that just fits the opening of the bowl. This will center it
automatically. Bring up the tail stock to hold it in place and turn off the
bottom leaving a small tenon. Sand the bottom you can reach. Cut, do not
pull, off the tenon. Sand that area by hand. Sign, finish and admire.
--
God bless and safe turning
Darrell Feltmate
Truro, NS
http://aroundthewoods.com
http://roundopinions.blogspot.com