Hello Francis,
The only two commercially available vacuum systems for solid spindles, with which I'm famaliar, are the Vicmarc Vacuum Plate (designed by Vic Wood) and the VaccuMaster Vacuum Chuck by Sierra Mold. The Vicmarc unit works quite well. The VacuuMaster I've never seen or had an opportunity to try, but I understand it works well.
To make a home made rig, I would consider buying the Vicmarc Vacuum Plate, remove the rubber seal from the plate and glue on or screw on a wooden plate. You can now cut grooves to accept pieces of PVC Pipe with rubber seals on one end similar to the Craft Supplies USA vacuum system. Since the plate is threaded onto the rest of the assembly, the part that mounts to your lathe and to your vacuum source, you should be able to turn bowls with thick bottoms and threads to fit on where the plate did. Put rubber on the rim of the bowl and you have a simple Oneway type cup. You could also use hot melt glue on the rim like Soren Berger to make a fairly decent seat. Warm the glue by light sanding before applying the piece to be held by the vacuum chuck.
Incidentally, you could use Petter Herod's method of inlaying epoxy into the wood to hold a good thread either cut with a threading jig or hand held chasers. Petter makes threaded boxes using colored epoxy for the threaded area. If would work in this case also.
I don't know whether this will help or not, but it is a few ideas to think about.
Fred Holder
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