On Sun, 21 Apr 2013 23:09:44 -0400, "Existential Angst"
wrote:

"Gunner Asch" wrote in message
.. .
On Sun, 21 Apr 2013 17:24:39 -0400, "Existential Angst"
wrote:

"jon_banquer" wrote in message
...
On Apr 21, 12:38 pm, "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

I prefer Balix as it's what I've used the most frequently. I've had
very good success with them. I have no comment on tap geometry. All I
have ever been interested in is the end result and how long the tap
will last:

http://www.balax.com/

=============================================== ====

Your balax taps seem to have 1 groove.
My nachi 1/4-20 has two; emuge 1/4-20 has 4, the 5/16, 3/8 has 5.
http://www.emuge.com/multitap/mt-form/selection.html
Sheeit, I paid list for those mutha****as..... ahma haveta to talk to
haas
about that.... LOL

My no-name 5/16 stuff has no groove at all, looks perfectly round, like a
screw.

Don't know what it all means.
One implication might be this:

With at least one groove, the tap can release air/coolant from a blind
hole.
One of my worries with the no-groove imports is that they might could
trap/compress coolant in a blind hole, and, well, coolant is
incompressible....
Don't know if that's a valid concern, but the thought did occur.

Double check and see if its perfectly round or not. A lot of form taps
have a slight "dip" in one side which is where air is released. Some
have a single groove along the side of a round tap. Same reason.
Blind holes dont release coolant when you stick a plug in them.

The 5/16 imiports I have are perfectly round!!
It probably is risky using these in a thru hole, never mind a blind hole.
Plug indeed.
I wanted to compare these to the emuge's, but breaking taps even in scrap
gives me the willies.... lol
Years ago when I first started using form taps I had some that
appeared to be perfectly round, however they were tri-lobed. Measuring
with a micrometer they seemed round, using a vee block and an
indicator showed the lobing.
Eric