Longworth chuck

Greetings,

Thank you very much for an excellent set of pictures and and instructions. They have answered some questions I have had for years.

Sincerely, Bill Thomas

I also made a Longworth chuck but when I looked at the basic design it seemed to have one possible drawback. On the inside of work the chuck needs to grip on expansion but, on the outside it must grip on compression. This seemed to suggest a need for two chucks :-( Due to the normal lathe rotation, depending on how the disks were assembled, it either gripped the work harder or tended to loosen. (If the work was gripped on the inside (of a bowl) or on the outside). It occurred to me that if the centre boss was made to protrude to both sides of one disk and the other disk has a hole a neat fit over the boss, the second disk could be fitted on either side of the first disk and the operation of the chuck could now be made to "self tighten" in the normal lathe turning direction, irrespective of whether it was gripping the inside or outside of the bowl or platter. In my case I made the centre hub/boss out of steel and use the 'spare unused hub' section, to go into my normal scroll chuck for easy mounting. I realize that this may be a bit hard to visualize but think of one disk having a hub (say 2" dia.) on both sides of it, long enough to suit the thickness of the second disk. The second disk is a copy of the first, except that instead of a hub in the centre it has a hole to suit the hub on the other disk. This makes it possible to mount the second disk to either side of the first, therefore changing the locking rotation of the Longworth chuck. To make it easier to use I colour coded the four disk sides, so red together is one position and yellow together is the other. If anyone is interested I can supply pictures of my version. Cheers,

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