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