On Sat, 31 Dec 2005 17:30:22 -0600, Jon Elson
wrote:

David Anderson wrote:
Jon Elson asked the right questions. The face mill worked fine on my
vertical milling machine. The trouble began when I moved the same workpiece
to my lathe and used a 1/2 inch dia Williams boring bar in a toolpost holder
to bore 1.500 inch dia x 3-inch deep, using a 3/16 HS steel bit (not
carbide). Both operations dry. I will try again with a freshly honed
cutting edge plus cutting fluid and maybe reduced SFM . Dave
There's your problem. Sometimes, I use an end mill as a boring bar.
A 3/4" or 1" dia end mill would make a much better boring tool than
your 1/2" bar. Since you need a 1.5" hole, there's no need to use
a small bar. And, since you need over 3" extension, you need something
stiff. Since you are using HSS, you can't go crazy on the SFPM, but
usually faster gives better finish. You should be able to run it at
1000 - 1500 RPM to get 400 - 600 SFPM.

One other trick. If you have a long boring bar, with a "tail" sticking
out the back of the tool holder, it can vibrate, and make a sort of
tuning fork. I have rubber-banded tool blanks and other stuff to the
back end of the bar to damp out these vibrations. If you can feel the
back end of the bar vibrating at ALL, then you need to make up some kind
of damper for it.

Jon

A long 2 flute (or even 4 flute) endmill makes a GREAT boring bar,
and is simply ****ing amazing when used with plastic. Just be sure to
set tool angle a bit so there is no drag.

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner