Ig,

I've come up with a potential application that would require me to
syncronize three rotary motions simultaneously. Similar to what you did
with rigid tapping, but with a non-milling machine.

However, it seems EMC^2 might be the tool to do it.

Would you be willing to share the code/system configs you used to sync your
spindle with Z for tapping?

Thanks,

LLoyd