"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:

whit3rd fired this volley in news:c22c8298-6339-48d0-
:

A plunge router and a suitable circular jig would be my choice for
this.


And my choice would be a Forstner bit. I make holes in HDPE a few dozen
times a year. Twist drills won't do. Spade bits make for rough holes.
Forstners - fed at slow rpm and an adequately fast feed rate to prevent
softening of the work - make for a smooth hole in one cut.


I got a smooth bottom but rough sides using the spade bit on a sample. For the
application it likely is good enough but I do like to do decent looking work.

The Forstner likely would be better. I may just order a forstner bit. McMaster has HSS
or carbide edged, which would you choose?

Wes