Well, that vacuum rig should be good to go, I got the "Sealed" bearing today, so I set about making up some new vacuum chucks.
Attachment 18895 Attachment 18896
OK, here are the pieces, I have four sizes of PVC pipe connectors for the bodies of the chucks, four threaded blocks and four chunks of of MDF for the backer boards of the chucks.
EDIT: I would NOT use MDF for the backer boards again, they leak BADLY and needed a LOT of CA glue to seal them. Use some good quality high grade plywood instead.
I pre-drill the threaded blocks, and countersink the holes.
I draw lines from each corner, on the MDF, and then line up the threaded block, and drill one hole, and drive one screw...
...and then drill the other three holes.
Once the dust is cleaned off, I spread the glue evenly on the two surfaces....
...and then drive the four screws to hold the block in place on the MDF backer board.
Now I have four backer boards ready to go on the lathe, once the glue dries.
I had two round boards from when I made the mini cyclone for the shopvac, so I used them, but the other two boards are square, so they had to be rounded off. Turning the MDF is MESSY, I use the DC and I wear the Triton Power Air Cleaner Helmet, and it is still NOT much fun
Once the piece is rounded, I then use the dividers to mark the outer size of the vacuum chuck body.....
and using the parting tool, I cut a groove in the backer board, to fit the vacuum chuck body. A good fit is needed, it should be snug, but not tight.....