On Jul 10, 3:38*pm, "Dave August" wrote:
...
If you stop the work from turning while the tool bit is cutting, either by
turning off the motor or disengaging the clutch, you'll most likely break
the tip of the cutter. Typically you disengage the halfnut and leave the
work turning, and yes it leaves a ring at the end of your threads.
.....
IIRC his explanation was that the tool holder, tool and work piece DO
deflect and when you stop the work with the tool engaged the "spring back"
force drives the workpiece backwards against the tool and snaps the tip
off...
--.- Dave

Interesting. When there isn't room for an end groove I stop the lathe
short and pull the belt to finish the pass, then chisel and file out
the stack of chips at the end of the thread afterwards. Maybe the tip
never has broken because the cut is only 2-3 thousandths, or the old
South Bend 10L is -so- springy it doesn't have enough force to break
the tip. I keep the belt loose enough that the cutoff bit can jam
without breaking.

Jim Wilkins