In article ,
Ted Edwards wrote:
DoN. Nichols wrote:

O.K. I finally got time to go down to the shop and check.
They are TNMG. Now -- why did I mis-remember the designator that badly.

Thanks, Don.

Anyway -- it should be just a chipbreaker groove, but it behaves
nicely on my 12x24" Clausing, which suggest the either it is working as
a positive rake modification, or that the Clausing is rigid enough to
handle negative rake tools. :-)

Probably the later. :-) Get a hold of a TNMP and compare it to the TNMG
with a magnifier (or, if you wish, I could e-mail you a close up photo
of the two side-by-side.) You will find that the "chip-breaker" groove
of the TNMG goes _almost_ to the edge leaving a narrow flat to produce a
right angle edge and thus negative rake.

I don't have the TNMP available to examine, but the TNMG does
have the slight flat. But with a heavy cut, it is ripping the metal
apart wide enough so it doesn't touch where the edge would be, anyway,
and thus is acting as a positive rake tool to all effects. (Granted,
you have to be able to take that heavy a cut. :-)

The groove in a TNMP goes
right out to the edge to produce an eighty degree angle. When the TNMP
is angled down 5 degrees, it still has 5 degrees _positive_ rake.

O.K. Are these coated or uncoated inserts? If coated, how much
does that dull the edge?

Enjoy,
DoN.

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