Re: Rigid tapping: how is it done

David L Anderson wrote:

> From: David L Anderson <daveland@...>
>
> People have made comments to about "rigid" tapping. Can anyone provide a meaningful
> description with an example?
>
> What features must a CNC mill have to do rigid tapping?
>
> Can EMC do rigid tapping?

Rigid tapping means the spindle of the machine must advance precisely one thread pitch
for each revolution of the spindle. It must also stay in sync when the spindle motor stops
and reverses, to back the tap out of the hole. This means a machine with minimum
backlash, and a position encoder on the spindle. The programming is VERY similar
to the way a CNC lathe is programmed to cut threads.

I don't know of any machines currently running EMC with spindle encoders, although
somebody recently set up a lathe running under EMC. But, a previous incarnation
of EMC did run a VMC with rigid tapping. I believe that was at GM Powertrain.

Jon