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Melting down Knives from Police Amnesty - Random one!


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Hi everyone, I'm based in Bristol UK and I desperately need some advice. 

I have got in my possession thousands of knives from a police amnesty we did 2 years ago. I want to now melt them down and ideally, eventually make some kind of sculpture to commemorate victims of knife crime.

I have absolutely no connections (the person who was going to do it has passed away) and wandered if there are any pointers from this community.

I would be so grateful for any advice

 

Nick

Edited by Mod30
Correct terminology
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Rather than melting them down, could you forge/fabricate them into a sculpture? While still a large task, it seems like it would be easier than melting (note: this would be melting not smelting, there is a difference) the very likely random collection of different alloys in that pile of knives and trying to recast it.  Plus you would have the added benefit of the starting material being recognizable from a distance which would draw people in to read the sign, poster, etc. describing why it was made.

For inspiration, see the thread on The Wrenchman.

 

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Quick vocabulary note: "smelting" is the process of extracting metal from ore, while "melting" is turning existing metal into liquid. What you are asking about is "melting".

That said, Rojo Pedro is correct that melting steel is very difficult. It takes a LOT of energy (the melting point of steel is much higher than, say, copper), and safety is a real issue. Liquid steel at 1371-1540°C can cause a lot of damage if it starts flowing across the floor. Even worse is if it hits some water (in an improperly dried mold or the like), as the water will instantly flash to steam, expand to 1700 times its liquid volume, and carry any liquid metal with it as it explodes through the workshop. Not good, not fun.

However, if you're not committed to melting the knives and casting them into something else, you have a lot of options. The idea that immediately springs to my mind is to weld them into something else. Imagine a sculpture of a baby cradled in a pair of hands: from a distance, it simply looks like its subject, but when you get close, you can see that the entire surface is made of knives welded together. That's a pretty powerful image of creating something tender and vulnerable out of something designed to do harm, completely harmonious with the intentions of the knife surrender program. My only recommendation there would be to be very careful about welding through chrome plating on the knives (the fumes are very bad for your health) and also pay attention to proper pre- and post-welding heating of the blades (hardenable steel can crack in the heat-affected zone if you're not careful).

(Addendum: I see that Frazer posted the same idea at the same time. Clearly, great minds think alike.)

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Any historical sites in Sheffield still teeming cast steel on a demo basis?    Otherwise a cast steel industry can melt them down but they would be part of a larger charge of scrap metal---could be tons.  The one where I used to live used arc melting with 3 14" diameter graphite electrodes and each one was running around 5 kiloamps! 

If you have no background in melting and casting; steel is considered one of the harder and more expensive metals to work with. The proper protective gear is quite expensive and MANDATORY!  Working with molten steel is life threatening dangerous.  My  general analogy when folks ask about this is that you are asking about winning Formula One races and also how to start the car...

If your Railroads use thermite to weld rails together you might be able to get them to stack up all the blades in a circular tower, handles out, and set off a charge in the center that would melt and weld them together.  Again use the experts!

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What fun is that Anvil? I think detonating rivets would make a dramatic kinetic sculpture. How about build walls around it with numbered boxes and hold lotteries on BANG days. Hmmmm?

Once blunted they could be welded or riveted point out in flowers on hubs so they turn in the wind as kinetic sculptures. Knife blades are already pretty much air foil shaped. 

Frosty The Lucky.

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