The first thing you need to know is how many tons of force you need to punch a
1/4" square hole in 1/16" stainless sheet. The second thing you need is the
smallest and cheapest tool which can yield that tonnage. I had a Whitney Jensen
Model 91 10-ton bench punch which would have worked perfectly for you, but I
suspect you may be able to get away with 5 tons, in which case you can use a No.
8 hand punch like http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7576272205
and you can order a 1/4" square punch/die set from a lot of people. If you get
lucky when you buy the punch, you may be able to solve your problem for under
$100. Punching is *always* the way to go for sheet metal.

By the way, when the time comes to actually punch, lay out the centers of your
holes, and carefully centerpunch them. Then after the part is all centerpunched,
put the part in the punching tool and feel with the tit on the tip of the punch
until it picks up your centerpunch mark, then keeping it firmly located in the
punchmark, punch the hole. That's how to put holes right where you want them.

GWE

wrote:

Bill Schwab wrote:

Darren,


Nothing can be outsourced, and I'd need the tools and know-how for
future projects anyway.

These particular squared holes will be about 1/8" from the
edges(corners) of the stainless steel.

The square holes are necessary because I'm creating a hinge set-up
where I'll need put squared Delrin bushings with round holes through
them into the square holes created in the 1/16" thick stainless steel.
The holes need to be square so that only the rod that will go through
the bushing will turn and not the bushing itself.


Dumb question: do the holes need to be square, or merely have flat
sides? If the corners could be rounded, you could mill windows using a
small-diameter endmill. Cutting SS will make it more fun than simply
milling a window w/o undercutting (which is a good challenge in itself),
but I suspect you could do it. If there is an SS-related problem I am
missing, others will correct the record.

I am a little confused about the rotation constraint. Is there only one
hinge on each plate? If so, it seems very likely to bind??? If there
are two or more, it should not be able to rotate even with round holes.

Funny how things make sense only after pusing the send button - it
sounds as though you are trying to get something to turn, and to hold
the bushing in place. If that's the case, then scratch the two-point
comment, but it seems that a window would work if you are willing to
round the corners of the bushings, or if you deliberately undercut the
corners to make room for the corners of the bushings. The bottom line
is that you might consider doing something simple with the SS that gives
you the same effect as a square hole in it.


Here's a clarification.

Imagine a 4" X 4", 1/16" thick stainless steel plate layed flat with
four stainless steel rods sticking out from each corner.

To accomplish this, I'll have to cut a 1/16" slot in the end of the
rods so that each rod can slide over it's corner of the plate. Now
there will also have to be holes drilled down into each rod *and*
through the plate so I can drop a Delrin cylinder through each of them.

Concentrating on one corner, since the plate which is only 1/16" thick
will over a relatively short time cut into the Delrin cylinder because
of it's turning motion, I have to place a Delrin bushing in the plate
hole first, and the bushing has to be square so that it does not turn.
And if the bushing doesn't turn the plate will not cut into it.

Thanks a lot.

Darren Harris
Staten Island, New York.