Hi Derek

The vacuum chuck was covered by the etc., G I do have the setup but
don't use it very much.
You have the same problems with the vacuum as you have with any setup,
chuck etc, like holes and warping and size, especially small and
warped, as the surface area is small and the holding per square area,
1kg per cm2 or 15lbs per inch2 does not add up to much.
As for cost it does not have to be that high, a good little compressor
or vacuum pump does not have to cost very much,(Bill Noble has always
had some nice pumps for sale and also some of the accessories etc) and
the hardware if you don't have any lying around should not add up much
either, the vacuum chucks you can easily turn yourself.
I do use the jumbo jaws on my Oneway stronghold a lot, and with the 8
buttons very often there are only 4 holding because of the warping of
the bowl/platter shape, but you would be surpriced to see how close one
can get the turning to center, by pushing and shifting while tightening
up.
Then some tape wrapped around or as some use the plastic klingwrap you
can get a good hold on a piece, but again as you also know there are
limits to shape and size you can hold.
Couple of pics. in this album show my vacuum setup, it's just visual
though.

http://homepage.mac.com/l.vanderloo/PhotoAlbum25.html

Have fun and take care
Leo Van Der Loo