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Subject: Making square holes in thick Aluminum Plate
From: (njrich)
Date: 20/11/04 04:24 GMT Standard Time
Message-id:

Gentlemen,
Hope you are fine wherever you may be.

I have a job which came my way which calls for making 2"x2" square
holes in 3/4 inch aluminum plate.
I am a construction worker, carpenter, with access to a heavy
mill-drill machine and a small home shop size band saw. I have to make
24 of these square holes in separate 5" x 6" x 3/4" sections. The
tolerances are not tight. + or - .01 inches is ok.

My question is what is the best way to do this? From what I can see
there are three choices.

1. Layout the square, drill a 5/8 hole, put a hacksaw blade through
and start hacking away. Finish off
using an end mill. Of course I might need a new set of arms when I'm
done. i need a new brain already!

2. Due the same but weld the bandsaw blade through each plate and cut
using the band saw before
finishing with the mill.

3. Drill out a square shape formed by a series of holes using a 1/4"
drill bit and finishing with the mill.

My 3 ideas might suggest to you that I have little experience with
machining metal. And that would be
quite true. So I would appreciate your suggestions.

If it was just one hole you could do it any way that came to hand. For 24 holes
in 3/4" plate you could be there for a couple of days with the wrong method.
Ideally it wants a laser cutting machine which would slice them out in a few
minutes. You might be better off finding someone who can do that and adding a
markup.

If you have to mill it out then I'd suggest a smallish 2 flute milling cutter
and do it in maybe 2 passes each 3/8" deep. Forget sawing. You'll still have to
clean up the edges and the sawing won't actually save you much milling time.
--
Dave Baker - Puma Race Engines (www.pumaracing.co.uk)