On Sun, 10 Apr 2016 11:08:12 -0000 (UTC), John Doe
wrote:

I never said "don't take it literally". When someone says something that
cannot be taken literally, then normal people assume it means something
less than the literal meaning.

Every square is going to have round corners. According to my research,
some sophisticated tools for cutting square holes leave rounded corners.
In my case, they can be significantly rounded, but I'm probably not
going to spend that much for this project.


John B. wrote in
:

On Sun, 10 Apr 2016 00:11:01 -0000 (UTC), John Doe
wrote:

Researching the issue... I see some ways to drill a square hole in
aluminum for hundreds of dollars.

Seems to me an inexpensive do-it-yourself way to do this slowly would be
to place a stencil pattern square over the material and then use a drill
or rotary tool with the cutting surface of the bit below the pattern.
And just move the tool around until it hacks the hole square. It might
be accurate enough if done carefully. But the rotary tool needs to be
held perpendicular while being moved around. I guess it could be done on
a rotary/router type table, while moving the material instead of the
cutting tool.

Any keywords for that sort of thing?

Thanks.

Great. You designated a square. How do you cut the 90 degree corners
with a round tool bit?

Or as you say, "don't take it literally", can the "square" have round
corners?


I wrote:

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.

You know, I used to give you some metalworking tips and then you got
snotty about it, so you're not going to get any more out of me. But I
can give you a piece of advice that will help you get better answers
from others.

The people on this NG know every way under the sun to make "square"
holes, and that's been a challenge for machinists for a couple of
hundred years. As soon as you said "perfectly square," the folks here
rolled their eyes, because that's a sure indicator that you have no
idea what you're talking about, and your options are limited to the
things that a tyro might be able to accomplish. That really puts some
limits on what they're going to suggest.

There is no "perfectly square." The question is, what are you going to
do with that hole, once you've cut it? Maybe it doesn't matter if the
hole you drill to start it goes over the line a bit. If that's so,
then you can use your hand drill, or whatever you have, to drill a
1/2" starter hole. If you can't, and have to drill a smaller hole,
then you're in for some heavy filing, or you're going to need a
diemaker's single-side chisel to rough out the hole.

Don't have one of those? Then you'll need a coarse double-cut square
file to do the job in maybe 10 - 20 minutes. Don't have one of those?
If you have to use a slim-taper triangular file, you're in for an hour
or so of filing, with lots of stops to use your file card and you'll
have to keep de-pinning your file, because fine-cut files are terrible
in aluminum.

Don't have those? Then, for chrissake, tell us what you're going to
use the hole for. Then the people here who have done it can tell you
what your options are. Unless they have an idea of how "clean" that
hole has to be (in other words, if it has to be free of overcut with
the drill), and how straight the sides have to be, and how square the
hole has to be, and what radius you can tolerate on the corners,
you'll go around in circles trying to figure out how to cut a square.

So, instead of just specifying a "perfectly square" hole gag!, tell
people what you're trying to do, and what the hole is for. Then you'll
get right down to some useful suggestions -- but not from me.

Are we OK now?

--
Ed Huntress