I think the backlash involved in the carriage feed on most lathes would
result in some damage to the utting tool, or the closest end of the thread.
The operator would also need to back the cutting tool away (quickly) from
the workpiece when switching to reverse (at the same time, actually).

As Jim suggested, there probably aren't many good uses for rapid reverse on
a lathe (common, manual models).

--
WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Bruce L. Bergman" wrote in message
...

Threading toward a face is one of those - but IMO it would be both a
whole lot safer and easier to go the other way and go from the face to
off the open end. If your timing on hitting that Stop button isn't
dead-nuts perfect, you have a crash.

Or do it on a CNC machine that has a lot better reflexes than you
do, and should know precisely where the tool is at all times.

-- Bruce --