J. Clarke wrote:
Was cutting a 3/16" wide dado in a piece of Lyptus using an Amana
upcut spiral bit. Was cutting 3/16 deep in half inch stock. Router
is a Porter-Cable 7518 in a lift.

All was going well, when, after cutting four pieces, on the fifth one
I'm about three inches along and all of a sudden the bit comes right
through the top--it's still cutting just decided to pull out of the
end of the collet. So I put it back, socked it down hard, and
continued the cut and three inches along it did it _again_.

Okay, that was something I'm glad you shared.

Am I correct to calculate that the upcut spiral creates a force that is
trying to pull the bit out, and a non-spiral or a downcut would lessen
the chances of that happening but not remove it completely?