Universal Jam ChuckComments (0)
As any turner of bowls, plates, and vessels knows, you need a non-marring way to reverse-chuck your nearly completed work to remove any tenon, waste block, or excess material that was used to mount the piece by its bottom. Commercially available jumbo jaws and vacuum chucks will often do the job, but tend to be expensive, and may not fit your existing 4-jaw chuck. This is where shop-made jam chucks come to the rescue. Often made as a one-off single-purpose unit, a jam chuck mounts in the lathe headstock and provides a friction-fit cavity or surface that the turning can “jam” against. The tailstock is usually brought into play at the same time to press the work against the jam chuck.Of all the jam chucks I’ve used, there’s one type I reach for the most. Resembling a sort of doughnut-shaped bowl, this multi-use marvel is the closest thing I’ve ever seen to a “universal” jam chuck. Faced with neoprene rubber, its rounded rim will tuck inside larger bowls to grip them. The chuck’s concave center can be used to nestle the rounded top of a small vessel, or to cradle a sphere. It can even be used to drive plates and other flat pieces, using the crest of the chuck’s rim as the bearing surface. In short, this is one lathe workhorse you’re gonna love.
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