I bought a piece of stainless shim stock thinking myself over clever to use
in the solution of some minor adjustment problems. It arrived today, and it
just occurred to me that I have no idea how to cut it cleanly without
curling or damaging the edge.
So, what's the best way to cut it?
I wouldn't know the best way, but I can tell you how I cut some when I was
replacing a reed valve on a little compressor. I sandwiched the stainless
between two thin pieces of sheet steel (I think it was pieces of an old
paint-thinner can), holding the sandwich tightly and close to the cut in a
vise, and cut through the sandwich with a cutoff wheel in a Dremel.
It cut clean, but it was tricky to keep shifting the sandwich in the vise.
I have cut reed valves for Cox 049 engines out of sheet brass with tin
snips, and rubbed the edges flat again with a burnisher (well, the
handle of an X-Acto knife, but I said "thou art a burnisher" before I
Well, tinsnips are OK, a full bench shear is better, and if the edges
matter I've used etching after putting a pattern on in Kodak photoresist
(the spraycan type, UV exposed...) like printed circuit fabrication
Fastest material removal was with some mild nitric acid solution,
but that's a bad idea if you don't have a fume hood, because there
are some brown gasses involved.
If it's fairly thin, like .010, then just a sharp scissors or shears.
For thicker, decent tin snips will work fine.
When you're getting into the .040 and up range, you might want to find
someone who has a shear. ;-)
How thick? If not too thick, you can use a sharp pair of paper
scissors for straight edges and reasonable curves. I use them for
0.0015" steel shim stock.
A bit thicker, perhaps tin shears such as are used in air
If yet thicker, you will need a shear -- with the gap adjusted
according to the thickness of the stock.
If you are the one wanting rings of shim stock, you will need to
make a guided punch to make clean burr-free edges.
I don't think that the suggested knife-edge steel against a hard
rubber backing will produce your needed freedom from burrs.
If that edge has to be dead flat, as for a reed valve or certain electrical
connectors, I don't think a punch will do it in shim-thickness stainless.
Press tools to make burr-free IC lead frames, for example, typically have
tolerances of +/- 50 millionths of an inch or even closer. And the alloys
used for that are a lot less inclined to draw a burr.
It's all a matter of how burr-free you have to be. But any punch to cut such
thin stock cleanly requires EXTREMELY close punch-to-die clearances. Unless
the punched shape is round and the die can be turned, it's a bugger to make
Cut oversize with tin snips/scissors and Dremel/stone the burr off.
Alternative, use a thin cutting disk to chew out your piece. Another
alternative, use a standard sheet metal nibbler to cut the piece out,
then file to your scribed line. I've used all of these methods at one
time or another, just depends on how intricate the piece needs to be
and how thick. Nibbler can go quite thick for shim stock, maybe not
so thick with stainless as with brass, aluminum or mild steel. I've
punched thin shim washers out with a Whitney punch and spent a little
time with a diamond hone getting the burrs knocked back. Worked fine
for gun stuff.
I was applying electricity; the passivating layer on the stainless was
pretty easily breached, and then the nitric DOES attack the metal.
I tried salt, too (not as effective as HNO3). There must be a good
standard etchant, I've got a business card that's marvelously
detailed, etched in stainless, from Acu-Line (phone 206-634-1618
in Seattle, WA, USA).
I would be all gungho to do those with a CO2 laser.
Then I want a laser CNC machine anyway. "Yes, dear I did need to spend five
grand on EBAY fir a laser for my little CNC machine. I needed to engrave
some stainless steel business cards." LOL.