On 02/05/2021 11:03 AM, John Dammeyer wrote:
Hi Gene,
But it's also been reported that with LinuxCNC it's possible to stop the
spindle while still in Threading Mode and then turn the spindle by hand and the
carriage will follow. This is of course on a lathe. Not something you'd do on
a mill I think.
I did this YEARS ago when testing out the first versions
that supported rigid tapping and lathe threading. Of
course, it might not create the most perfect threads, but it
did seem to reliably follow the thread that was cut before.
If you get multiple threads when making multiple passes, it
may indicate the spindle index has noise on it. If it ever
gets a pulse at a different spindle angle, you will have
this issue, and it has nothing to do with speed.
Now, at least on older versions of LinuxCNC (and EMC2) it
was customary to run the trajectory planner at some
sub-multiple of the servo thread rate. Since the T.P. does
the spindle synch, that would cause the Z position to lag
the spindle. So, you want to make sure the T.P. is running
at the
full servo thread frequency.
Jon
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