Brian I realize that this will not be rigid tapping. But the test will give me an indication of the realtionship of RT and Mach possibilities. Another company does rigid tapping with a VFD and encoder on the spindle we should be able to do it also or get extremely close so that a spring loaded /floating taphead will keep us out of trouble. All we should have to do is follow the spindle rotation with the z axis. We do this all the time with x/y/z. I know Mach does not have the z/spindle relationship, but we have to start looking somewhere/somtime to move on up.