Another method I've used to cut threads was to put the tool on the far side of the part, upright, but running the lathe in reverse. You can see the tool more clearly than upside down.
Most often, I use a long travel dial indicator to cut threads to a shoulder. As the indicator hits the 0 mark, I retract the crosslide a full turn, simultaneously disengaging the carrige from the leadscrew. Sounds tougher than it is. I can make threads that look like the breakout is from a milled thread in this manner.
Last edited by Chuck H; 02/04/10 08:21 PM.