Bending 1/8 inch thick 7075-T6 aluminum

Hey all:
I'm wondering what it will take to put a 2-3 inch curve in a 21 to 24-
inch wide sheet if 1/8 inch thick 7075-T6 aluminum. I ask because I
run a business making stage weapons out of 1/4 inch 7075 plate, and
would like to be able to offer shields as well. Flat shields are
fine, but curved shields are more user-friendly. I realize that 7075
is not an alloy that is friendly to forming operations, but we're
talking about a slight curve in a relatively large, thin piece.
Specifically, will a 20-ton shop press (with a shield-sized stamping
mold attached, of course) do this job? I say 20 ton, because that's
the smallest size press that will accommodate a work piece at least 21
inches in width, and it's about what's in my price range.
Ultimately, I'm hoping to make both square shields and dished rounds,
but if these operations require heavy industrial rollers and spinners,
then I'd rather not spend the dough on such a large press. Does anyone
have any advice to give?
Thanks,
Nathan
Reply to
MrFightGuy
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The rollers on the 30" 3-in-1 sheet metal machine can barely handle 0.062" (1.5mm) 6061. The rolls deflect so the ends curve more tightly than the middle. 0.050" 5052 is noticeably easier to shear, bend and roll.
jsw
Reply to
Jim Wilkins
Nope. I've made swords out of 6061, and my 7075 swords pulverize them with little effort. It's gotta be 7075 so that the shields can stand up to the beating that my swords dish out. And no, I can't start making swords out of 6061. It just doesn't have the tensile strength (and therefore the durability) I want in my products.
Reply to
MrFightGuy
Thanks, yeah, but I'm trying to keep this purchase under $300. The HF bress brake/slip rollers are way out of my range, and their 12" slip roller is way too small for what I'm trying to accomplish.
Reply to
MrFightGuy
I see nobody with great knowledge answering your query. I'm not an expert but 20 tons has to be a great plenty to press AL to the curve you desire.
Of course if you have the dies, getting press work would be trivial and inexpensive. My query would be how to make dies without the huge expense of machining from billet.
Karl
Reply to
Karl Townsend
SWAG: I'd think aluminum has a higher strength than that.
pi x r x r = 3.14 x 12 x 12 = 452.16 sq. in. /88.46426 psi. I'd tend to disagree that the 20T press would work, but how much of the bending -would- it do, I wonder?
Home casting, I'd wager. My buddy cast some nice little sprockets after machining one from plate. He likes piston aluminum for most things he cast. My CNC router holder is one of his castings that we machined. Maybe Nathan has beaucoup 7075 scraps and shavings, so he could cast from them. It beats a $2/lb return from the scrappers.
-- When a quiet man is moved to passion, it seems the very earth will shake. -- Stephanie Barron (Something for the Powers That Be to remember, eh?)
Reply to
Larry Jaques
What's the actual shape of the objects? Maybe the aluminum distributors or manufacturers could tell you the pressure required for the doming, which I'm sure is the higher pressure requirement.
-- When a quiet man is moved to passion, it seems the very earth will shake. -- Stephanie Barron (Something for the Powers That Be to remember, eh?)
Reply to
Larry Jaques
Ask the fighters in the SCA how they make dished shields and stuff. Go here and look around until you find a group near you, then visit and ask questions.
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technomaNge
Reply to
technomaNge
Do you really mean "bend" or do you want to "dome" the piece? If you want a 2 or 3 inch high "dome", lay the piece on a flat hard surface, like an anvil and just start hammering in ever increasing circles, from the center of the piece with a slightly rounded hammer and the piece will start to dome. More ever increasing circles = more doming, until or unless the material work hardens to the point where it starts to crack. I don't know that alloy very well, but if you can anneal it now and then, you can keep going.
A farrier's hammer would be a good one to use. A ball pein hammer has too much rounding and will simply make a bunch of little round dents. Even those dents will work, but the result will not be pretty.
If you are not making a lot of these, assuming that "doming" is what you want to do, call around to body shops to find someone with an English wheel and ask if you can get a lesson or two and then rent it. Slower, but pretty.
Pete Stanaitis ---------------
Reply to
Pete S
I have made inquiries with some of the big web suppliers for the Society for Creative Anachronism. Everyone except one or two suppliers makes shields in 6061, which is infinitely more pliable than 7075. Those who do sell shields made of 7075 tend to sell them in flat shapes. This in and of itself is not disheartening, as the SCA uses weapons that are either light practice schlaegers or larger weapons made mainly of rattan. They don't need shields stronger than 6061. I'll check out that link though... you never know...
Thanks,
N
P.S. What's "Meridies"?
Reply to
MrFightGuy
Nathan, By curve do you mean a domed surface? (Like this?
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Or a straight shields with a curve lengthwise? (like this
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Different methods for each one, with the crusader style being much easier in a small shop using a simple roll bending press that you could build easily.
Reply to
Steve W.
That's what the test strips I suggested will tell you, without wrecking large sheets.
My ultralight tent has poles made of 7001 which cracked when strapped to a motorcycle.
Reply to
Jim Wilkins
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From the above link, it seems that spring-back will be a problem. You'd probably need the ability to anneal the piece at 900 deg.F for 3 hrs and do controlled cooling. Also the link says that it helps to do forming at 200 - 250 deg.F.
Reply to
Denis G.
I think Snag is suggesting the English wheel sold by HF. An English wheel is what I would try to produce a domed shield. Maybe someone here that has an English wheel will step up and relate their experiences. Or maybe someone would be willing to let you ship them some aluminum to see how well their English wheel works.
=20 Dan
Reply to
dcaster
I would expect the HF one to bit a bit lightweight for doing 1/8" aluminium even in a soft condition. I have a much heavier wheeling machine and that did dish some 5mm 1050 but it was hard work and the piece required quite a dish so in the end I just resorted to using a domed former to push the aluminium into a piece of pipe with a piece of 5mm UHMWPE between the pipe and aluminium to spread the load and prevent marring of the surface. This was done in a fly press so blows could be done quickly and controlled and allowed the dished pieces to done quite fast. Once I got it set-up and done a practice piece I could do a 250mm blank to a 250mm radius in about 5 minutes with repeated blow going around the piece. Not a job I would want to do with a hydraulic press due to their speed.
Reply to
David Billington
Pete:
Um...yes.
I'm going for domed rounds and curved heaters (pentagonal shields) and kites (shields with an elongated triangular shape). And yes, a 2-3 inch curve is what I'm going for. Any more, and it makes the shield trickier to use. And yes, I'm looking to eventually make lots of these. The Society of American Fight Directors includes sword and shield in its curriculum, so a lot of their certified teachers want lighter alternatives to heavier steel weapons.
Thanks for the advice. An english wheel may indeed be the way to go....
Nate
Reply to
MrFightGuy
Okay...keep in mind for the rounds, all I need is a 2-inch deep dish on a 21 - 24 inch piece. HF has a pneumatic planishing hammer that sells for just over 100 bucks and gets good reviews from customers, but I don't know if it'll even put a dent in 1/8 inch thick 7075.
Reply to
MrFightGuy

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