square hole in box mod?

[DaveSignal]

I've got enough parts to do two more hammond box mods. I'd like to do another G box and a B box. The B box I am probably going to wait for shapeways.com to print a voltmeter bezel, but the G box I would like to fit a voltmeter like my last mod... except the voltmeter I have is a smaller .28 meter. This size will work better in the G box. I see no problem using my Dremel to cut out the long sides of the rectangular opening needed. The short sides, though, are smaller than I think I will be able to use my cut-off wheel. So how do I cut out this opening?

ETA: my current idea is to drill two holes and then dremel the long ends. I don't have a metal file, but will then look for one at the hardware store... hopefully something exists that is small and square.

 

[stevegmu]

A square broach tool would cut a perfect square hole out of a round hole, but they aren't inexpensive...

 

[drmarble]

I use a small square file to make rectangular openings. It is about 3/16" thick and 1/4 to 3/8" wide. It is rough only on the wide sides. It works great for dna windows and squonk holes. It slices through Hammond boxes very easily. I can make the openings as square as I have the patience to do so. I have no idea where I got mine, maybe a garage sale, but they should be easy to find.

 

[DaveSignal]

I use a small square file to make rectangular openings. It is about 3/16" thick and 1/4 to 3/8" wide. It is rough only on the wide sides. It works great for DNA windows and squonk holes. It slices through Hammond boxes very easily. I can make the openings as square as I have the patience to do so. I have no idea where I got mine, maybe a garage sale, but they should be easy to find.

Thanks for the tip. I was able to make a nice opening simply by drilling and using a small file that I found at the hardware store. Pictures are here.