Roger,
Now that you have high confidence in the threading may want to play around with the
different thread cutting feed methods. You may even be more surprised on the results of
your systems ability to do threads. Example; Alternating flank infeed to do a acme thread
with a single point threading tool. HP requirement is greatly reduced!
Just for info:
Back many years ago tried to get slaving of the spindle to the Z axis.
We had enough problems just fixing the Mach3 threading when it was broke.
So never happened.
Why the slaving? Because back manny years ago a DOS controller allowed that, and using an mpg
one could just move the Z at varing feedrate along the stock, back and forth, to do
threading. It was a model makers dream since you could easily do threads way smaller
than 0-80's.
Matters not how good a controlling device addresses threading. If all the other items
of the lathe system ( which includes the operator ) is not applied correctly for the
task success will not occur. The nut goes on has it's place, but, meeting design intent
and spec are the name of the game.
Have fun,
RICH