On Jul 30, 10:55 pm, joel wrote:
all combinations of
fast/slow feed rate, fast/slow RPM, large/small cut seem to make no
difference.

None of those words are numbers. Machining at this level is a numbers
game for the most part. A "heavy" cut is different for different
people.

We'll assume you're using an actual boring insert and boring bar.

What feed and speed combinations have you actually been using (numbers
please!)? Did you look up the recommended feeds and speeds for the
tool you're using? That info should be available in the same catalogue
from which you selected the boring tool, and it does make a difference
so make sure!

Your boring tool sits no more than 3-1/8" out from the tool post....
RIGHT? Overhang is *really* important when you're boring.

With brass, you can always go slower. If I was having problems, I'd
probably run at 400 or less RPM to start. Feed rate is *heavily*
dependant on the insert so look it up! The cut should not be squeeling
ideally. Work to get rid of that or you'll see it in the surface
finish.

Good luck. Learning is difficult but worthwhile.

Regards,

Robin