On Apr 12, 1:19 pm, tww wrote:
This is an FYI for anyone who does not get American Woodturning and is
thinking of getting Coles jaws to hold bowls or looking for perhaps a
better way to finish the bottoms of your bowls so I'm not expecting
any replies.

The Spring 2008 American Woodturner (you can order a copy from the
American Association of Woodturners web site if you are not a member)
has an interesting article on the Straka chuck. It is used for
reverse chucking. I wish this article had appeared a few years back.
Rather than buy a second chuck and jaws to hold bowls up to 8", I
would have made one of these chucks instead and been able to hold
bowls up to 12" (I have a 15" lathe). It is also a cheaper way to
go.

The chuck has a faceplate connected to two plywood disks (glued
together) potentially as big as your lathe can hold. Next, it has a
plywood ring held by bolts to the first disks. Finally there is a bowl
sandwiched in between the disks and the ring if you can picture all
that. The article has pretty good directions on how to make the
chuck.

I was bothered by that article, which gave someone credit for
inventing this chuck that has been called a Donut chuck for many
years. A fellow near where I live, Vernon Librant, has been using this
form of chuck to turn the bottoms of his very large bowls for many
years. Vernon uses rings made of unbreakable plastic and for the most
part uses only two bolts to hold the bowl to a flat board of about 8"
width. He cuts a groove in the board to fit the bowl rim then mounts
the bowl and holds it in place with one of his plastic disks with a
hole in the middle for the bowl bottom and two bolts to hold the plate
to the backing board. He turns some very large bowls this way.

I have personally used the process a number of years ago before I got
some chucks that hold bowls well enough to suit me and I don't have to
mess with the bolting on of a donut disk. The vacuum chuck, the
Longworth Chuck, the Rim chuck by Richard Benham are all in my
inventory for holding the bowl to turn the foot. Actually the Rim
Chuck has become one of my favorites for this operation. However, all
of these methods, I'm describing still need the tailstock most of the
time while turning the foot. The Donut chuck does not need the
tailstock to hold the bowl on to the chuck.

Fred Holder
http://www.morewoodturning.net