What diameter and material are you threading? Maybe you're asking for more than what the spindle motor can provide. IRC it's only got a 3/4hp motor. If you're cutting a large diameter at high RPM, you might not have enough juice to push a constant RPM when more of the cutter is engaged.
You may have to compromise by stepping down to a higher torque setting if you're threading a large diameter. It's too bad, but it seems that Mach3 uses the index flag only to start the threading pass instead of using it to adjust the feed based on the instantaneous spindle rpm at each flag pass. |