Tim Wescott wrote:
On Sun, 25 May 2008 02:44:56 +0000, Jim Chandler wrote:


Karl Townsend wrote:

Most likely, you're dealing with part deflection. It bends away from
the cutter, making it larger the further from the chuck,

Very finely sharpenned and honed tooling helps a lot with this issue.
if you've got it, super high RPM and a light finishing cut help too.

Karl




Thanks, Karl. I'll give that a try. I hadn't thought about deflection
because I thought everything was solid.

Jim


Zero deflection, eh.

It's amazing just how elusive 'zero' can be when you start looking hard
enough.



That's what happens when you're not a real machinist and are judging
things by feel. It is amazing how weak things really are. The first
time I tried turning this thing I had a 3/16" bolt threaded all the way
through it with a nut on the end cinched down tight. I chucked it up
and started turning. About the third pass, I got a little overly
enthusiastic I guess, and took too big of a cut. The bit dug in and the
bolt bent nicely right behind the nut. I was amazed. you don't think
of those things. At least I don't.

Jim