John R. Carroll wrote in
rec.crafts.metalworking on Wed, 15 Dec 2010 17:11:57 -0800:

For a REAL production run....a few thousand holes, I'll set up the
reversing tapping head on the VMC and spin that at about 2500 RPM

But that is just me....your mileage may vary

Mike

A Fanuc Robodrill (CAT 40 VMC) will peck tap 1/4-20 UNC holes at 10,000 RPM.
That's not just me.
Your mileage won't vary.

At work we just got two new robodrills. Smaller than CAT 40. And boy
can it move. It was tapping some small parts so fast, you couldn't
see the spindle stop and reverse. If tapping blind holes with a roll
(forming) tap, you have to go slow to give the coolant a chance to
escape. The thing sounds like a dental drill when milling.
--

Dan H.
northshore MA.