Im trying to understand how its possible to cut threads without stopping the spindle.

The x feed rate and spindle rpm must be related and then you just pull out of the cut
go back to start, feed in a little bit more and your good to go?
How do you know your starting the next run at the same place the thread started.

Right now, Im doing a controlled number of  revolutions stop the spindle  reverse and retract out the same way.
Feed in some more and redo.

Thanks

JOHN,
Mach's CNC threading cycle is described in Threading On  the Lathe  which can be found in Members Docs.

RICH

Single point threading with a CNC lathe is just like threading with a manual lathe in the respect that the spindle doesnt stop  between passes, there is no need as the only thing that needs to be in sync is the Z axis to the spindle speed. On a conventional lathe that is achieved by mechanical gearing and engaging the half nut at the correct time at the start of each pass. On a CNC lathe the controller does that by watching the Index pulse and starting the Z axis at the correct time.
Hood