Part of the fun of cutting threads is working up to the bolt head, and
stopping just before you crash! Usually people use a rear mounted tool and
run the lathe backwards if this is a big issue. Using an upside down tool
and running backwards will tend to lift the carriage off the ways, which is
bad. Often there are no gibs to hold the carriage down, just the normal
cutting force.

Center drill the bolt head for a live center in the tailstock, hold the
off-cut portion of the shank in the lathe chuck, thread normally from the
bolt head as far as you need and then chamfer and part off the bolt.

Brian


"Ben" wrote in message
om...
i just successfully threaded my first bolt, only to discover i was
threading left hand threads. aaargh!
how can i thread right hand threads while starting the thread at the
bolthead?
how can i hold the bolthead with the tailstock and center the end of
the bolt with a live centerin the spindle?
i'm thinking about grinding a tool to cut threads upside down.

xxxxxx
xxx
x
xxxxxxxxxx versus


xxxxxxxxxxxxx
x
xxxxxxxxxx