"John Doe" wrote in message
...
I need to cut a 1/2" square through 1/4" aluminum. It doesn't have to
be
centered, but the dimensions of the hole need to be correct.

I'd like to use a router type tool that I made, but the aluminum
would have
to be perfectly square.

Any tricky way to do that?

Thanks.

If the tops of the fixed and moving jaws on your bench vise are the
same height you can use them as a filing guide. If not you could rig
up something, perhaps with a drill press vise or steel bar stock.

Lay out your square with a sharp scriber, drill out the middle and use
a coarse file to approach the line, then align the scribe mark with
the top of the jaws and use a safe-edged "hand" or "pillar" file to
finish cutting up to it. The tops of the jaws guide the file
perpendicular to the hole as you near the line.
http://www.amazon.com/Nicholson-Pill.../dp/B006P2XM2U

With care you should be able to file within 0.005" of the intended
size.
--jsw