Here it is, Vincent. The Grumbine chuck makes it possible to do a natural edge bowl, and is do-able......but, if a turner wants to do more than one or two of them, I can see where a vacuum setup would be much more problem free.....other than the overall expense, of course!
The orange rubber ball compresses into the interior of the bowl, and the foot area is exposed for turning the final version of the foot. These photos were taken just after I made this Grumbine chuck, and I have since used a leather strip between the outer plate and the bowl to prevent any marking on the bowl. The long screws make it possible to finish turn the foot on different heights of a bowl, and I believe the maximum width bowl that this chuck can accommodate is 12". A standard large 8" faceplate is used to mount the chuck to the lathe spindle.
The last photo is someone else's Grumbine chuck, and shows a bowl mounted within the chuck. This photo served as my "model" for making mine.
-o-
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