I broke down and purchased a set of 60 degree plastic/laminate/fiberglass drill
bits from
McMaster Carr. They perform on fiberglass as expected. almost no cracking, and
no
grabbing. They make pretty round holes close to size of bit. The secret is the
cutting
edge is 90 degrees. Works so nice.
In addition, when working on hinges, they are the perfect tool to drill centered
through
the fiberglass into and through the aluminium hinges.
Having such a sharp 60 degree angle centers things so nice.
Anyway for precision alignment, i use a 60 degree center drill to make a small
pilot
hole, then go at it with the 60 degree plastic/laminate/fiberglass bit.
End result is hole is a lot rounder, diameter is close to drill size, and
position
of
hole after 2 passes is close to spot on.
I have 118 degree bits, and 135 degree split point jobbers bits. The 135 degree
is poor
for drilling out a smaller hole and keeping things centered. The 135 degree
points
are
however do good for hard steel, or if using a drill press and you do not want to
use
multiple drill bits and just make 1 cut. For not too precision hole placements,
they work
OK in a hand drill.
For some reason McMaster does not have them in Catalogue near the drill bits,
you
need to
look up in the index for location.
Ron Parigoris
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