On Sun, 23 Apr 2006 08:00:03 GMT, Gunner
wrote:

On Sun, 23 Apr 2006 00:53:51 -0700, "Harold and Susan Vordos"
wrote:


"Gunner" wrote in message
. ..
snip----

there has to be a better way.

There is, and you won't believe how simple it is.

I think it's Stanley that makes an adjustable circle cutter. It's a fly
cutter of sorts in that it uses a 1/4" HSS lathe toolbit that is held in an
arm with a set screw. The body has a 1/4" drill that acts as a center, so
all you have to do is set the arm out to spin the circle you desire and cut
away.

Before you jump to conclusions and suggest to me that it won't work, be
advised that I cut all the openings in the 400 amp switch and the CT can for
my 3 phase service with one, using a half inch Milwaukee drill. I cut
several holes.

Yep! Did them by hand, and it works great. Requires a little skill, but I
know you could handle it easily.

Remember, the items I cut are made of steel. Cutting aluminum would be a
breeze. It does require some skill in grinding the tool, and constant
lubrication, but you can handle that with something as simple as an acid
brush.

Harold


This is exactly the sort of cutter I first used..which broke.

I suppose I could scale it up..beef it up when copying it.

The trick to this, other than very rigid workholding, is how the tool
is ground. It needs to be radiussed or tapered so the tail doesn't
drag in the cut. If nothing moves and you're curling a nice chip,
the stress on the cutter really isn't that great -- it's just cutting
aluminum, same as in a lathe -- but side stress will snap it in a
heartbeat.

I have a Val-Cut trepanning tool I found at an auction that can easily
make 8" dia holes in 1/4" aluminum. The crossbar is about 22mm square
while the actual cutter is ground from a 1/4" square HSS toolbit. Kerf
width is less than that, maybe 1/8". Needs lots of lube.

I've had best luck drilling 3 or 4 holes in the part that will be
scrap (hole or disc), bolting it tight to a thick piece of wood and
clamping the lumber to the mill. Ya need the other part of the
workpiece clamped too so it doesn't get away from you at breakthru.
Lock X & Y tight, feed with knee.