On Mon, 11 Jul 2005 02:11:41 GMT, Orval Fairbairn
wrote:

In article .com,
" wrote:

I need to cut a panel to mount one 3.125" and one 2.25" What size hole
saws do I use? Do I use smaller sizes, say 2.125" for 2.25" and 3" for
3.125"? Thanks.


I use a fly cutter sized to each hole size and then finish off the holes
with a "slapper wheel" sanding wheel. I have tried the hole punches and
hole saws, but prefer the fly cutter, in a drill press set to the lowest
speed. That way, I have the best control over the hole-making process.

Your drill press must run much slower than mine:-)) Even at the
slowest speed mine is far too fast for a fly-cutter of larger hole
saws. I prefer to use the fly-cutter chucked up in a good quality
floor mill.

A fly-cutter, at least in my experience will give the best finish to
the holes of just about any method including knock-out punches which
tend to roll the edges slightly. It's also easier to get all the
holes right where you want them which can sometimes be difficult with
the larger knockout punches. OTOH it takes a bit more skill to
sharpen the bit and to set up a fly cutter, but you can get a hole
that only requires breaking the edges to finish them up.

Hole saws tend to give a rather ragged edge and want to creep although
that can be minimized. A really sharp hole saw will do a pretty good
job but you have to be careful about it grabbing.

As for the size of a hole saw to use I go with one just as close to
the proper size I can get, while still staying under sized. I then
finish out the hole using a sanding drum. The larger ones take less
skill (and work) to keep the hole edges circular.

No matter which method is used, clamping the piece down with the
proper clamps and wood blocks (to protect the metal) is very important
from both the finished result and safety.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com