Re: [CAD_CAM_EDM_DRO] Using a tapping attachment with a CNC bore cycle

"Fitch R. Williams" wrote:

>
> >Just make sure what ever you do, that you underfeed the tap in.
> >Procunier's use a cone clutch that locks up even harder as pressure
> >increases. Get ahead of the tap a bit and you run the risk of breaking
> >the tap, or maybe even something in the head. Underdriving in both
> >directions will do nothing more than increase the wear on the clutches
> >somewhat, not likely to cause you any problems.
>
> Makes perfect sense. I'll run the spindle as close as I can to 90% and
> see what happens. It will radically underfeed coming out but that
> shouldn't be a problem.

I just used the RPM as stamped on the milling head nameplate, plugged it
into a formula, and used that for the feedrate. It worked superbly, and the

only 2 taps I've ever broken with it were caused by feeding too DEEP, not
by feed getting ahead of the spindle revolutions. Watching the head
smash a 6-32 tap into the workpiece, I'm not very worried about breaking
the head. In forward motion (compression) the two parts of the clutch
are the input shaft and the output shaft, so the head is actually pretty
sturdy. One trick is to manually activate the two clutches to free them
up. Sometimes they stick while the unit is stored, and can cause problems
on the first hole.

You may find you don't want to pull up at the same rate as the down-feed,
as the clutches may chatter quite a bit, possibly even marring the hole
or breaking the tap. I think it would be better to match the 2X 'unwind'
with the correct feedrate. It is pretty easy to do.

> I also bought a New In the box New Tapmatic N/C-R1 Tapping Head with an
> NMTB40 adaptor (which matches my mill) on Ebay for around 25% of the
> catalog prices. It covers the next size range up (#10 to 1/2"). I
> figure I'll practice with the Procunier which was less than sixty bucks!
> Once I get the hang of it, I'll try the other one.
>
> I am guessing that since the spindle is always going in one direction, a
> single stop works fine?

Single stop? Oh, for keeping the body from rotating. Yes, that works
fine for me!

Jon