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David Billington David Billington is offline
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Default Dangerous chuck mounting? 12" South Bend chuck

Ignoramus11200 wrote:
Look at this pictu

This is a 12" lathe chuck for South Bend lathes.

My question is that the mounting seems to be a simple thread. There is
no "lock" like there is on L type mounts, or on camlock chucks etc.

So, it could happen that the big chuck would unscrew itself during
stopping if RPM was too high, the brake was applied too vigorously, or
something broke inside the gearbox. The chuck weighs about 100 lbs, so
having it bounce around the shop would not necessarily be a great

Am I missing anything?


One of the guys I was in high school metal shop enjoyed spinning up the
chucks on small Southbends and putting the lathe in reverse, causing the
chuck to unwind and drop off and roll across the floor at speed. After a
few occasions he was warned and didn't do it again. Would have seemed a
good idea to not provide reversing on a threaded spindle lathe for novices.

When in Wichita I recall the lecturers mentioning an occasion when a
student had a chuck come loose and roll down between all the subsequent
lathes, causing the students to jump out of the way. All the lathes were
in line and the chuck rolled down the line until it hit the far wall
IIRC. Those lathes were Rockwells, not highly regarded by the
instructors IIRC, but not fitted with threaded spindle either.