That's what he means by the zero rake. What he means by the 90 tip
angle is the included angle of the tip, instead of the 118 or 135 of a
regular jobber bit...


a 10 penny nail flatened on the end with a hammer and put a 90 degree
tip on it works fine, same as above, for plastic. Always drill an
oversize hole because the plastic will move around quite a bit with
tempature changes. The common thing to do is to drill a hole oversize
and put a piece of rubber hose on the screw that will go into the hole
and stick slightly outside of the plastic. The rubber is soft against
the plastic and also allows the plastic to move.


John