"robobass" wrote in message
...
I'm new to high speed machining. I'm cutting a brass part
http://i1262.photobucket.com/albums/...63/Chatter.jpg
with a 4mm HSS Co TICN cutter. The surfacing works fine, but when I
try to make a deep counterbore I get a really bad finish. I'm running
the tool at 10k rpm (spindle range is 8k-25k rpm) and the finishing
pass at F300. I'm not sure what my F values actually mean, like in
ipm, but it looks like a good speed. I suppose my my options are to
use a carbide cutter, go to 6mm diameter (max on this spindle), or
adjust the feedrate and spindle speed. Can anyone take a look and make
suggestions? I know I should get myself a proper knee mill, but that's
not a realistic option for me at the moment. I'm hoping the machine I
have
http://i1262.photobucket.com/albums/...r1963/CNC1.jpg
will be adequate if I tweak the operation enough.

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

I suspect you won't like what you see if you put an indicator on the
head to measure deflection and pull on it with a spring scale.

I got a chainsaw finish from milling meter cutouts in 0.030" sheet
Aluminum with a 1/4" end mill with flutes 2" long, which I was using
to clear a forest of clamps. The reason was tool flex, not the
machine; a 1/2" diameter cutter gave a smooth finish at the cost of
more filing to square the corners.

My 700 Lb Clausing's spindle deflects ~0.001" per 25 Lbs.

-jsw