# Question about cracks when bending metal



## Saau (3 Jun 2018)

Good morning,

I was hoping someone could enlighten me about the likelihood of relatively thin sheet metal cracking when bent. I'm trying to work out which sort of metal and thickness would suit my purposes best, as I was on the verge of buying 1mm thick aluminum sheets when I read that it cracks easily when bent, which would be very problematic for me.

This may sound a little odd, but what I'm wanting to do is incorporate an engineering-style action into a live action role play game. I want to simulate engineers having to repair a breach in a spaceship's hull by (lightly) hammering out a number of twisted/folded pieces of metal and reassembling them into their original shape, much like a jigsaw.

I had planned just to buy some sheets of metal, snip them into a rough jigsaw, and bend the pieces to make them look like wreckage. But research has since led me to believe that this amount of bending, and then unbending from the players, could likely cause the metal to crack and break if I'm not careful.

So can anyone please offer advice as to how this may work? I'm assuming aluminum is right out, but would another type of metal be more forgiving?

Many thanks,

Saau


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## sunnybob (3 Jun 2018)

forget ali. Totally unsuitable for continued bending, especially if hammering is involved.
Copper will take a lot of bending before cracking, and its a lot easier to work with than ali or iron.

Brass maybe if you can get thin annealed sheet.


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## Obi Wan Kenobi (3 Jun 2018)

I agree with Bob regarding the ali, and if you choose copper that's 1mm thick and 1 m square is going to cost well north of £100 :shock: 

OWK ccasion5:


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## dynax (3 Jun 2018)

what sort of scale are you working in, it may be more cost effective to use something like a heavy duty baking foil and fold it to get a reasonable stiffness,


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## Saau (3 Jun 2018)

Thanks, that's useful information.
I was only looking at small sheets, maybe 15cm square or some such, just enough to simulate the players patching a hole up. I want the metal about the strength that you could bend it by hand with a little force, but I'd want them using pliers and a hammer/mallet just for safety's sake rather than getting their fingers near any potentially sharp edges. 
I'm assuming 1mm of copper is going to be harder to bend than 1mm of aluminum, so if I were to go with the copper I could probably go to a thinner sheet.
Cheers,

Saau


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## thick_mike (3 Jun 2018)

Tin, lead and copper all bend better than aluminium. But any metal you choose would have to be thought of as a consumable, they will all fatigue at some point.


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## lurker (3 Jun 2018)

What about a beer can, I have found this quite useful stuff for a variety of purposes 

Can easily be cut with a pair of scissors


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## sunnybob (3 Jun 2018)

What? you mean other than holding beer?
Damn, wish I'd thought of that.


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## chiokli (3 Jun 2018)

thick_mike":1bwk5sin said:


> Tin, lead and copper all bend better than aluminium. But any metal you choose would have to be thought of as a consumable, they will all fatigue at some point.



+1 - Any sheet metal will work harden as they beat and form it cold. Best to use 0.5-0.8mm aluminium sheet for the cost saving and consider your pieces consumable after 1 or 2 uses. At least with thinner material, it'll be easier to replace them with a pair of shears and won't be as sharp as steel sheet.


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## TFrench (3 Jun 2018)

I'd go with tin can gauge aluminium. 1mm is hard work for hand tools!


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## AES (4 Jun 2018)

Not being a video games player, nor a watcher of "Game of Thrones" I'm having some difficulty picturing what you want exactly. But the main requirement seems to be the ability to bend, by hand, from flat sheet into what, a 90 degrees bend? And to do it several times over with the same piece?

That's asking a lot of any material, but I agree with the above, even thin sheet ali will soon crack, then break, if asked to do this several times. Copper would be better, especially if annealed first, followed by "half hard" brass if you can find sheets. But in all cases they're going to crack and break after several bends ("up" then back flat again).

And doing the bending by hand you need to remember 2 things - obviously the thinner the sheet is, the easier it is to bend, but also don't forget, the WIDER any sheet is, the harder it becomes to bend by hand.

PERHAPS a food tin with both the top (of course!) and the bottom cut off with a tin opener, then cut (tin snips or fine hack saw or jeweller's saw) along the seam will provide a suitable material for a while - some tinplate is pretty good at resisting cracks when it's bent. But even if you find a suitable tin (trial and error), it WILL crack and break in the end. Some quicker than others, it depends on the thickness and type of the parent metal (MS sheet).

Does it have to be metal at all?

How about thin cardboard (suitable colour) laminated with transparent plastic? From time to time Aldi and Lidl both have plastic laminating machines on sale quite cheap, plus packs of the pre-glued plastic folios in A5, A4, and even A3 sizes. I bought one, plus a pack of the folios, and use it for "info sheets"to hang in my shop. The plastic stuff seems pretty tough and with a, say, piece of silvery-coloured cardboard inside could look quite realistic (if that's important), plus it resists cracking (therefore ultimately breaking), for quite a time.

Otherwise I have no ideas, sorry.


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