On Sunday, April 21, 2013 12:38:01 PM UTC-7, Existential Angst wrote:
Awl --



I've taken to form tapping aluminum (cnc rigid tapping mode), and have

noticed a wide variety of geometries in these taps.

The name-brand form taps I have (Nachi, Emuge) almost look like cut or hand

taps, as they have between 2 and 5 sharp-edged flutes.

I have others which have no flutes whatsoever (they look almost like a

screw!), and others with a slight recess instead of a true groove,, and one

that looks almost oval.



Any insights into the preferred style of form tap? Does this style vary

with context, metal, etc.??

Suggestions on best bang fer the form tap buck?

--

EA

EA:

You're asking this in rec.crafts.guns.politics?? Silly Wabbit, you might have better luck in Practical Machinist. g

Form taps really don't have FLUTES per se, but most have LOBES. The vertical grooves on the taps (if it has them - not all do), is to primarily get lubrication to the working area of the tap, and secondarily to relieve pressure in blind hole tapping.

The following is an old article from Cutting Tool Engineering magazine, but it still contains good basic info.

http://www.ctemag.com/dynamic.articles.php?id=197


--
BottleBob
http://home.earthlink.net/~bottlbob