Replies

1. 
   john_c2 | May 06, 2022 04:14pm | #1

   I never had luck with them. They don't hold well, and bowls kept flying off. I made a donut chuck, and think it's far better. But I'm not a great turner, either.

2. 
   EdWeber | May 06, 2022 05:36pm | #2

   IMO, Longworth chucks are the worst in terms of effectiveness and flexibility.
   Cole Jaws (jumbo jaws), Donut chuck or a Vacuum system are all more effective option for reverse turning. They hold more securely and are capable of securing objects other than round

3. 
   rob_ss | May 07, 2022 03:57am | #3

   Another vote for cole jaws.
   There is nothing inherently wrong with Longworth chucks, and they are incredibly cleverly designed, but as will all compromise solutions what you gain in one area, you lose in another.
   The infinite variability of grip and the easy setup come at the price of firmness of grip.
   The spiral grooves in the chuck mechanism are of necessity quite gently inclined away from the radius. The steeper you make them, the firmer the grip, but also the more stress is placed on the connection point at the hub, resulting in a tendency to distortion - that extra gripping force has to go somewhere after all, and the longer the groove, the less solid material you have as the groove of course takes up space.
   I am sure it should be possible to make one that works better and provides a more positive grip, but it would require narrower grooves in metal of significant thickness. A high cost for only very small benefit compared with the cheaper option.
   The time taken to change the position of the grips on cole jaws is such a small fraction of the time required to make a Longworth chuck that they are all but pointless to construct to have the convenience of a quick clamp down.
   That having been said, you still need the tailstock in as much as possible when reverse chucking to limit the risk of stuff going flying...