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Cutting stainless steel sheet?

 
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TroyO
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Joined: 07 Nov 2005
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PostPosted: Thu Oct 30, 2008 8:52 am    Post subject: Cutting stainless steel sheet? Reply with quote

Has anyone found a handy dandy way to cut 18Ga stainless?

I've tried a jigsaw... which kind of worked... until it didn't. (Blade up in smoke and even with a "shooting board" the cut wandered a lot.) and a recip saw, same thing. I was using gear oil as a lubricant.

I have been thinking about mounting a 4 1/2" cutoff wheel in circular saw (My junky one... LOL) and trying that. I do have an angle grinder as well... but there's no way to guide that along a rail for straight cuts.

I've seen a 14Ga (mild) 18Ga (Stainless) electric shear at Harbor Freight.... anyone know if it sucks or might actually work?

Anyway... my next shot at it is going to be getting a Bosch metal cutting jigsaw blade and just slowing the saw wayyyy down and trying again.

Any one have the magic suggestion?
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jegner
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Location: Texas, USA

PostPosted: Thu Oct 30, 2008 2:25 pm    Post subject: Reply with quote

Some sort of tin snip maybe?

Jim
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TroyO
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PostPosted: Thu Oct 30, 2008 5:01 pm    Post subject: Reply with quote

When I was making SCA armor for fighting (Which is how I ended up with this sheet of stainless in the first place, LOL) I was using a "Beverly shear" knock off from HF. It worked, but was real touchy and wasn't very good at cutting straight lines. It was OK to trim around stuff, especially if it was curvy and you had to watch where you were cutting anyway. "Aviation" type snips don't really do much but get angry at it... LOL.

I'm going to stop by Home Depot tonight and eyeball some jigsaw blades.... I've read some good reviews on the Bosch T123 blades. I'll give one a shot and review it.

For the record, I found some reviews on the 14 Ga Harbor Freight electric shear and the consensus was that it didn't work very well. I suspect from some of the reviews that careful setup, sharpening and shimming of the blades would make it work OK, though.
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TroyO
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PostPosted: Fri Oct 31, 2008 8:56 am    Post subject: Reply with quote

Yay! I finally have sucess!

The Bosch blades cut quickly, but were prone to breaking. They were a bit too aggressive for the cut, I think. (Odd the package specifically mentions cutting metal sheet and lists stainless.)

So, I went back to a 24TPI "Cobalt" bi-metal blade. I also slowed the jigsaw wayyyy down and it worked. I just ran it along a straight edge to keep it straight, and kept the saw below about 200 RPM. (3-4 strokes a second.)

Too fast and the blade burns up... too slow and it's jumpy and hard to control. Somewhere n between is just right and it settles in to a consistant 1/8 inch per second or so cut. It seems to be a balancing act between teeth per inch and saw speed.

To that end... I used an old beater jig saw I picked up at a yard sale. From back in the days when saw bodies were cast aluminium. It had a variable speed trigger with a little thumbwheel that you could set the max speed with.

I can't imagine trying to do it with just a variable speed trigger.. I think blade breaking and burning rates would go up from the inconsistancy. So, look for a saw that lets you set the speed with some kind of dial rather than just trigger pull.

Slow, but effective!
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crashmann
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PostPosted: Fri Oct 31, 2008 6:18 pm    Post subject: Reply with quote

Excellent information, and thanks for sharing with the group!

When I was upgrading my platen to 1/8" aluminum, I had to cut 1 3/4" square notches in the corners. I also used a jigsaw with a metal cutting blade and Boe-shield oil. Just like you found, a moderate cutting speed yielded the best results.

Fortunately, I bought the aluminum from a metal working warehouse, and they were able to cut it to the exact dimensions I needed. I should have asked if they had a sheet metal brake to make nice sharp corners. Maybe next time...

Charlie
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TroyO
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PostPosted: Tue Nov 04, 2008 9:48 am    Post subject: Reply with quote

Update on this.... I got it all cut out. I only used one blade after figuring it out, LOL. I did swap blades at one point, after the end caps but before the main body.

I had them, and it didn't seem like breakage or wearing out was an issue but I figured I might as well go into the biggest cuts with a fresh from the box sharp blade.

I eventually gave up on running the saw along a straight edge and just eyeballed the line. It worked a lot better. Maybe someone with a better saw would be OK, but in my case, to cut straight the saw actually had to be "crabbed" a degree or two from straight. Once I did that the cuts were probably within 1/32 of straight and some touch up on a belt sander too care of the rest.

I probably could have done simething like they do with bandsaws to correct for "drift" and spaced out one end of the saw base so it would cut straight, It was easier for the few cuts I had to just eyeball it.

Anyway... I'd reccomend anyone else making a stainless oven go with 22 gauge or thinner, LOL. 18 Ga is just really way overkill.
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TroyO
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PostPosted: Tue Nov 04, 2008 9:59 am    Post subject: Reply with quote

Ohhh, and Crashman... I too thought about having the place I bought the metal from years ago make the cuts and bends. It probably would have turned out better, but then I wouldn't have learned as much, LOL.

Now I have a lot better understanding of working with the stainless sheet for straight-line type purposes. I learned a lot about dishing and shaping organic-type curves from making armor but never really had a need for that type of straight edge, box type work before.

So... yes, anyone reading the thread... you will probably get better results taking it somewhere to be cut and possibly formed. I don't think it would even be that expensive.... I would guess maybe $50. When I got the sheet in the first place they cut several 4" strips for me, and cut the remainder in half for free. (Of course, I was dropping $160 on the sheet at the time.)
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fz1
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Joined: 04 May 2008
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PostPosted: Tue Nov 04, 2008 11:29 am    Post subject: Reply with quote

Wait till you try to drill it. LOL
Stainless will work harden real fast if any heat gets to the material.
You did the right thing slowing down the blade speed. The rule for any stainless work is less speed and more feed. If you let your cutter noth get a good bite into the material it will dull the cutter or heat up a small spot of the stainless making it hard real fast. There goes your sharp cutter in almost an instant. A friction wheel in a air die grinder works good if you have this setup. If you can make a drawing of your part needed it is best to have the shop fabricate it. Sometimes much easier than all of the messing around trying to do stainless yourself.
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TroyO
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PostPosted: Tue Nov 04, 2008 1:52 pm    Post subject: Reply with quote

Yeah, drilling will be another fun point, and there's lots of it.. LOL.

Current plan is just a hand held battery powered drill. I haven't decided if I may even want to use the 7.2V one because it turns slower than the 18v.

I plan to center punch and put a drop of oil on each one before drilling.
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Stomper
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PostPosted: Sat Nov 08, 2008 6:33 pm    Post subject: Reply with quote

Stainless also has a "grain" to it. You can sort of feel it "crunching" when cutting it with aviation snips... BTW- they make SS rated snips, you shouldn't use "standard" snips when attempting to cut it with snips... typically they have blue handles/grips... but not always. Wink


Also another note, because of that "grain" SS should be bent using an adequate brake ("box & pan" or "straight") to make your bends.
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TroyO
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PostPosted: Thu Nov 13, 2008 12:47 pm    Post subject: Reply with quote

I didn't have a brake, but I did have a hunk of angle iron mounted to the bench and a BFH. (Big farkin hammer). It worked. Wink

I also didn't notice the grain effect.. maybe that is more apparent with thinner sheets?

Anyway...I wasn't going for decorative, so functional but ugly was good enough.

I will say... it was AMAZINGLY easier to bend over 1 inch tabs than to bend a sheet in the middle. The tabs were basically wack it and go.... I even used a plastic mallet to try and avoid marring stuff up too bad.

Had I known that ahead of time, I would have made the oven in 5 pieces (4 walls, and top) and riveted it all together instead of making it in 3 pieces (U shaped middle and two end caps) and having to bend that U in the middle of a sheet. Hell, I spent 2 hours on those 2 bends and maybe 30 minutes on the other 6. I figured it would be easier to bend, I just underestimated how much easier, LOL.

The difference between having someone else bend it would still mean riveting it and spending an hour plus. Add in the time loading raw sheets in the car, waiting for it to be done, picking it up... it becomes pretty much a toss up. If I were to do it again, I'd still probably make it myself.... it would just go a lot faster this time. LOL.

Ohhh, and with cobalt drill bits it ends up that the drilling was no fuss at all. I think I did all the holes (200-ish) in about 30-40 minutes, with a few extra to go back and chisel off the burs and wack it with a wire wheel. No problem. The cobalt bits worked much better... they got a faster "bite" into the metal and required a lot less pressure to get curlicue swarf from the hole. Regular "Titanium nitride" bits worked just fine as well, just slower and with more pressure.

Soo... upshot is that the shell is now made. I am stringing up insulators and will start posting some pics of the overall process soon.

Moral of the story.....
Buy Cobalt Drill bits and run the drill at medium-ish speeds.

Get a good 24 TPI cobalt bi-metal jigsaw blade and run it at really slow speeds.

Use cutting oil... I used a mix of turpentine and gear oil. Motor oil would probably be fine too.

fz1 has the right idea... less speed and more feed. My little bro had the same advice, but of course I didn't listen to him.... he's my little bro. ;-P

Now... for the ulterior motive.... 18 Ga stainless would probably make a great battlebot frame.... and now I know enough to take on that project. ;-P
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taurus66
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Joined: 08 Nov 2010
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PostPosted: Mon Nov 08, 2010 1:42 pm    Post subject: Reply with quote

I have to say the best way i have for cutting perforated stainless sheet is with a 4 1/2" angle grinder fitted with an ultra thin (0.8mm)stainless graded disc.
Sliced through it like a hot knife in butter, and the spinning disc seems to keep it fairly straight too.
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