Re: [CAD_CAM_EDM_DRO] EMC Thread Cutting?

Ozzie@... wrote:

> Is it a practical possibility to use a closed loop EMC system to
> accurately cut threads by putting a rotary encoder on the lathe
> spindle and feeding that info to the X axis stepper motor controller.
> I would think that the feed rate and spindle speed should approximate
> that needed to cut the desired thread and then the exact calculated
> numbers loaded into the machine .ini; but then it should work; no?

This is done all the time on CNC turning centers. There is some
question whether
EMC has all the code set up to make multiple passes when threading, in
otherwords,
does it pick up the thread at the same point of rotation, by use of the
encoder index
pulse. It has to do this to take multiple passes while threading.

If EMC does not handle this at this time, it should be fairly
straightforward to
do this. Apparently a very old version of EMC that ran on an
experimental
(and not very successful) Windows NT platform did run a turning center,
and
did handle the threading. This feature hasn't been tested in a while,
from what
I can determine. The other thing that is nice, but not necessary at
first, is
constant surface speed. These are the two things that are not run into
on
milling machines.

Jon