"Arch" wrote: (clip) I cobbled up a cheap 'n dirty version of the too
expensive Escoulen chuck using a trailer hitch ball and pipe nipple & cap
welded to a faceplate. (clip)
^^^^^^^^^^^^^^^
Arch, let me tell you about the chuck I cobbled up afterI saw Escauen demo
his chuck. I starts with vacuum chuck setup, using a large, thick wooden
disk, mounted on the spindle. Turn the face of this wooden disk to a
concave spherical surface, of (maybe) 10 or 12" radius*. Mount your work on
a circular bowl shape chunk which can be stuck to the large spherical
surface, being held on by vacuum. You can offset the axis by any amount
that still covers the central vacuum port, and here's the beauty of it:

Unlike the Escaulen chuck, this one orbits the part of the wood closest to
the headstock, while the other end stays on axis, because every radius of
the spherical surface describes a cone whose tip is 10 or 12" from the
vacuum chuck*, and on the lathe centerline. This has the following
advantages:

1.) The part of the wood that is farthest off axis is firmly held by the
chuck.

2.) The part of the wood that is farthest from the chuck is spinning on
axis, so it does not take much of a beating as it is being turned, and you
are not "cutting air."

3. If you are careful to match the size of the work to the radius of the
spherical vacuum chuck*, you can use the tailstock for additional support.

4. There is very little chance of having the whirling end of the work whack
your fingers, or catch the lathe tool.

*If you want to take the trouble, it is possible to make chucks of various
radii, to match the requirements of different jobs.