Hi George,
lathe threading is largely enacted by the motion controller, not Mach.
I have been using Mach4 and an Ethernet Smooth Stepper for a year and its still not quite capable of lathe threading. The issue is not Mach4 but the
Smooth Stepper, the plugin is not capable of it yet. Large chunks of the code to get it to thread are written and in place but there is a bug. The expectation
is that the bug will be fixed over the next month or so.
To my knowledge only Vital Systems Hicon board is currently capable of lathe threading. I may be proven wrong and other manufacturers have got it working.
Still, the upshot is that the plugins required for Mach4 operation are still developing and lathe threading is at the leading edge of that development.
Mach4 will not advance your ability to thread with a lathe....yet.
Craig