CNC tapping 1

[mielke]

if you tap a hole in a cnc vertical mill about half way down and for some reason have to replace the tap and put a new one in the tool holder.

Would anyone try to finish the hole in the mill even if you try to align the new tap with the orientation of the old one. or would you have to take it out and hand tap it to finish?

 

[BrianE22]

I'd finish with hand tapping. With Rigid Tapping you'd be lucky to pick up the thread. With a floating tap holder you might have a chance. Even so, hand tapping a thread that is already started is easy.

 

[mielke]

I don't have much tapping experience. What exactly is a floating tap holder and how does it allow you to re-tap a hole in a mill?

 

[MikeHalloran]

A floating tap holder has an internal splined connection, so there is some axial compliance. I.e., once the tap grabs, the tap will feed at a rate governed by the tap's pitch; the spindle does not need to feed at the same rate, since it can't push on the tap until the tapholder runs out of stroke.

So if you change taps in the middle of a CNC program, and restart at that hole, a floating tap holder MIGHT allow the tap to pick up and complete the partially tapped hole instead of milling it out. ... whereas rigid tapping is more likely to both screw up the hole and break the new tap.



Mike Halloran
Pembroke Pines, FL, USA

 

[Jaydenn]

DO NOT attempt to re-run a tap that has been replaced.

The chances of success are so slim it just isn't worth the risk.

Jay