"PrecisionMachinisT" wrote in message
...

"Harold and Susan Vordos" wrote in message
...

"Pete Snell" wrote in message
...
Proctologically Violated©® wrote:


2 flute can plunge cut, 4 flute cannot.


Pete,
Not quite correct.
4-flutes come in "center cutting" and non-center-cutting varieties.
Center-cutting 4 flutes plunge readily. May not have quite the chip
ejection as 2 flutes, but they still plunge very well--may have to
peck
more.

Yes, I realized I was being pretty general, but most of the general
purpose 4 flutes don't center cut. (or at least they didn't used to.
I'm
getting kinda old and haven't had to buy a 4 flute end mill in a
while.....)

Pete

Your comments were quite on target for older end mills, Pete. I
recall
when the vast majority of 4 flute end mills not only were not center
cutting, but the center area was totally relieved. When rebuilding
such
end mills, the gashing process to restore the rake angle on the ends
eliminates the center area as well. Center cutting 4 flute end mills
are
far more difficult to grind than when using the gashing process.


Probly easiest just to take one flute clear past center while its chucked
in
the T&C grinder, then let there be a 'gash' in the other three
flutes--kinda
similar to the typical three flute centercutting end grind......

We keep a ~5 in dia x 1/2 thick white wheel on one of our bench grinders
at
all times just for the detailing of endmill ends....

It's dressed out something like this :

| |
| |
| |
| |
\ |
\ |
|_|

| |------.040in appx.

--

SVL


Pretty cool setup! Where I was trained we used a parting wheel and did
the gashing with the cutter grinder and an index head, so the rake angle and
chip relief was already established and ready to sharpen. Parting wheels cut
fast and cool and saves hand dressing time, but that's no big deal.

Sadly, we were not taught to make them center cutting. I especially like
your comments on the one long tooth. Would work great and be easier to
generate. Thanks for the tip! When that magic day comes that I have my
shop in full swing, I'll certainly put it to good use.

Harold