Shearing 18 gage stainless

Well, if you want to have a finished edge in one operation, and you don't mind getting crafty...

Build a very small/simple die with HSS lathe toolbits as the shearing edges. Stick it under a shop press of some description, or rig up a hydraulic cylinder.

HSS is tough, hard, and you don't have to heat-treat it. I'd likely grind a chamfer so that the bits can be welded into the die shoe. I'd also grind some shear ("V" ideally so it won't push your material to one side) into the toolbit which comes in contact with the scrap (if there is any scrap) as this will reduce your tonnage requirements (as well as snap-through) drastically. Entry to exit height difference should be one or two material thicknesses - any more and you're wasting your time/grinding wheel.

You should also grind perhaps 1 or 2 degrees relief on to the front (as opposed to top) faces of the tool bits so they don't get abraded away by the stainless halfway through the cut. Not absolutely necessary, but will help if you're doing a lot. Lube always helps!

If you leave some adjustability, you'll be able to control your cutting clearance. This is crucial (as well as having sharp cutting edges) to reducing your burr to an acceptable level while still being able to close the die (tonnage) and not wrecking your edges (tool life).

Unless you can use the contraption for something else after, you'd likely lose ($$$ wise), but I guess there's some value in building a tool that makes a tough job really easy.

Well, you were looking for "outside the box" ideas....

Regards,

Robin

I don't understand this part about the V.

An abrasive chop saw would certainly introduce heat discoloration to the material, but that does bring up the idea of using a wet tile / block saw with a suitable blade. If it's got continuous water cooling that should prevent discoloration. Probably can't use the standard tile or block blades, but a metal blade as typically used on the handheld gas

14" cutoff saws could probably be used.

What about one of these:

I've only cut heavier stock with the steel cutting blades in a worm-drive skilsaw, but they do sell blades intended for cutting metal studs and the like. Cut quality on plate is very good with minimal burr. The saw above turns at a slower speed than a normal skilsaw or chopsaw, which I imagine would be especially desirable when cutting SS.

I have done a lot of stainless sheet installs in kitchens and restaurants. My favorite tool is a 0.045" cutoff wheel in a 4-1/2" right angle grinder. It cuts really fast, is pretty easy to run a straight line and doesn't cause much of a heat affected zone. You don't get any distortion, which you can't say about shears or plasma cutters. Metabo and Makita both make good thin cutting wheels.

You will get a bit of a burr on the bottom edge, but that can be quickly removed using the edge of the wheel.

The more sheet metal I did, the less I used a plasma cutter. The plasma cutter causes too much distortion and really nasty burrs on the back side, on stainless steel. On steel a plasma is great.

For zero distortion of sheet you can use a nibbler, but they are very expensive if they can handle 18 ga stainless, plus it will really chew up the cutters.

Have you used it on stainless that thick?

I have used a couple similar ones, both electric and air powered, on aluminum, and they work well when sharp. I'd be interested in knowing how they work on that thick stainless as well.

Cheers Trevor Jones

This looks very interesting, Dan. I see that the KD-440 is rated for

16 gage SS, so it should have no trouble with 18 gage. It might take a bit of practice (and maybe a guide) to cut straight and square, but a bit of cleanup with a belt sander is certainly possible too.

I've used double-cut hand nibblers that work this way. They do a nice job on stock within their capacity -- which 18 gage SS certainly is not.

I'll check this out some more. Thanks!

Depending on quantity of parts needed - call a local Water Jet cutting shop. see what they would want for the job.

Wj's are cheap accurate and leave a nice edge

mark

Well, if the entire length of both blades contacts the sheet metal at the same time, you will require the highest tonnage to complete the cut.

To reduce the tonnage, you can grind one of the blades at an angle such that one end contacts the sheet metal first. As the blades continue to cut, the actual cut line moves along the blades. Because you've only got a limited length of the blades inside the material at one time, your tonnage is reduced significantly. It's like using regular scissors or shears. You're making the cut progressively as you squeeze the scissors.

Making one blade angled is pretty easy on a grinder. The problem is that this causes an imbalanced load. The moving members within the die are stressed unequally, which causes uneven wear (not good). Also, this tends to force the sheet metal to one side.

If you grind the blade as a "V" instead, you have a balanced load, and the sheet metal is not forced to one side. The problem is that it's more work to grind the V, and it will likely deform the cut-off section such that it cannot be straightened.

Just something to keep in mind.

Regards,

Robin

The OP said it had to be portable for site use, and last I saw, water jet cutters were anything but portable.

That would seem to fit with my idea of using a tile cutting saw, like a bridge type, with a suitable abrasive wheel for metal. The water cooling should eliminate the HAZ entirely, and the convenient bridge design should make it very fast to use for straight cuts.

Gottit. Thanks! I think there are several other viable options for this project, but I've little doubt that I will use your ideas somewhere eventually.

I had some 1/8" S.Steel sheared to 1" wide strips---watched them do it-great big ole 10 ft or 12ft shear---This stuff had been rolled so hard, I tried to mill a small pc to 3/32" thickness---It curled up out of the vise I was holding--it had so much internal stress in it.

I watched the blades of the press dull while they were shearing it-- you could see the different in the sheared edges from the 1st to the last shear---about 10 pcs cut---The tensile strength was 113,000 psi. Bearing strength @ deformation -138,000 psi !!