Harold & Susan Vordos wrote:
Make sure you use taps intended to be power driven. The typical hand tap
will usually lead to nothing but broken taps because they rely on reversal
constantly to break the chips. Nothing taps quite as well as a gun tap,
even in blind holes. Just make sure you have enough depth of hole to
accommodate the chip, which can usually be removed after tapping by using a
needle in an air hose nozzle. I keep several sizes of them in my toolbox
for just such an occasion. It's also a good idea to use only sharp taps.
Once they are dull, they usually lead to trouble, and are difficult to
re-sharpen with good results. Most attempts generally fail miserably.

I have a Procunier "CNC" tapping head. The difference is this one has no
overload clutch, and depends on the CNC to control plunge depth.

I do a LOT of blind holes, and the spiral FLUTE taps are incredible!
These bring the chip up the flutes and out the hole.

There are also thread forming taps, that make no chip. You need to
start with a larger hole, and these are for softer materials only.

It is just WILD to tap a bunch of holes at 300 -600 RPM, just zoom
in, zoom out, and on to the next hole.

Jon