I find drilling small holes in the kerf really helps on the chip clearance
with holesaws in aluminium. If I had that mill, I'd be tempted to put a
trepanning tool together and try that.

Brian


"Bob Swinney" wrote in message
news:AVTXa.73038$YN5.55452@sccrnsc01...
Ryan sez: "Will look into the holesaw type cutter, did not think they
made
one
that big,.."

They do, though. Not too long ago I cut a 4.5 inch hole in a piece of 3/4
inch mild steel plate. I'm not saying it was fast. The main thing is to
keep the chips from accumulating in the kerf. Blow or brush them out
frequently. Wear safety glasses if you blow - hi-velocity chips are just
so
much shrapnel.

Bob Swinney

"Ryan" wrote in message
...
Good point...

Have 10x50 table vertical milling machine, do not have cnc, nor a rotary
table.
RB



"Torsten" wrote in message
...
Depends on what tools you got.
A cnc could just cut out the center.
Manual machine maybe cut it out on a rotary table.
Other option would be a holesaw type of cutter single or multyflute.

A lot will depend on your machinery and tools.

"Ryan" wrote in message
...
I have a task which requires boring four 4" holes in .750 plate
aluminum,
with 10 plates in total to do. I have a boring head and / or
flycutter,
so
the finish cut will be no problem, it is just going to be a real
chore
to
rough them out I suppose. Short of using a jig saw (which I am not
convinced would work too well) what would be the best way to
approach
this
task? I would like to use the milling machine for the roughing, so
that
I
can rough the hole, then finish bore in 2 steps. Would a trepanning
tool
be
the best bet? If so, can someone suggest a particular model,
keeping
in
mind this job is meanial, therefore tooling costs are a concern.

Thanks in advance,

RB