Bob Engelhardt wrote:

This just for my curiosity, I'm not about to go CNC.

I assume that the lead screw is controlled independently of the spindle,
with its own motor, not through a spindle-linked gearbox. Or, is it
linked & the gear selection computer controlled?

If a separate motor, there is a huge range of speeds required: feed from
.0025 to .250 is 100:1 & that's multiplied by the spindle speed range,
say 200 to 2000 is 10:1. 1000:1 total. How do they do that?

If not a separate motor ... never mind.

Thanks,
Bob


The spindle is most times electronically linked to the feed screw
drives. This is needed for threading but not general turning. The
encoder on the spindle has three outputs, A B and Z. the Z is the
reference pulse and comes on once in every rotation. This pulse is used
to indicate the angular position of the spindle. When threading, this
pulse starts the feed axis in the same position for each cut of the
thread. The thread pitch is programmed into the control so that it feeds
as a function of the spindle rotation.


John