Gunner Asch wrote:

No idea. Ive bits and pieces of old sets and when I removed it from the
collet holder, it came out in two pieces. It was at least 20 yrs old
and came from a shop that did a lot of interupted cuts. Shrug

Wow. Never saw a collet insert break. I *have* seen the collet body crack many a time due
to overtightening.

First clue is a very long relative to diameter parabolic drill is putting holes in random
locations. Spindle running about 6K rpm so a that crack causes the drill to lean away
from the Z axis and start to whip due to centrifugal forces. Where the drill tip contacts
the part each cycle is random.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller