"Ken Moon" wrote: (clip) Also, I've considered trying to build a wooden
version of the Escoulen chuck to experiment with. (clip)
^^^^^^^^^^^^^^^
I have built a coupl;e of vacuum chucks that simulate the action of the
Escoulen chuck. Turn a wooden, faceplate-mounted piece of wood to a
spherical shape, and feed your vacuum through the spindle. Turn a sort of
flat bowl to stick to the spherical surface by vacuum. Attach your work
piece to this. You will be able to slide this off axis and hold it in
various positions, much as Escoulen does. To fully simulate Escoulen's
chuck, the spherical surface should be convex.

However, I prefer to use a concave spherical surface, which results in
having the work spin with the unsupported end on axis. This has some
advantages:
1.) It is less hazardous.
2.) It permits you to use tailstock support.
3.) Cuts that are made on the end of the piece, where it is weakest, are
made on axis--interrupted cutting (cutting air) is minimized, so there is
much less danger of catching and breaking the piece.