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Wanting to get into melting aluminum cans to cast stuff
June 22, 2015
7:17 pm
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chewmanfoo
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June 22, 2015
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I was thinking of buying something like this:

 

refRID=1HNA8JGS3FTBGPH690S8

 

Or build my own furnace.  Can anyone make any suggestions?

June 23, 2015
5:05 pm
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Lee Cordochorea
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It is important to know what the numbers mean. A "3kg" crucible for "precious metals" will hold 6.6 pounds of gold. Gold is more than seven times as dense as aluminum, so the crucible will hold less than a pound of aluminum. That's a bit more than six fluid ounces. Will this much be enough for your plans?

 

If it will melt gold or silver it will melt aluminum very easily. "1.7kw" tells me it will work on a 15amp 120vac circuit if nothing else is on the same breaker. A 20amp circuit would be better. You'll be paying for about a half kwh per melt at most.

 

What I don't understand is why the smaller one costs more than the bigger one:

 

If you would rather build one, plug the term "backyard metal casting" into your favorite search engine.

No matter where you go... there you are.

June 26, 2015
5:12 pm
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Matt Moore
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Building one isn't too difficult, a metal 5 gallon bucket, some iron pipe and fittings, a couple of bags of castable refractory, and tank of propane, and a leaf blower and you're in business. You can cast bronze too. I've seen people use steel crusibles for aluminum on youtube. I don't have experience with aluminum, but some with bronze.  The Astoria Meritime Museum has bronze casting class a couple of times a year, you don't need to bring anything for the class. It'd be a great way to find out if you like casting. Sam Johnson teaches the class, he really knows his stuff too.

June 27, 2015
9:03 am
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Morgan A. Kirk
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  If you're not casting very much, using a coal forge with a smallish crucible works pretty well; you just have to make sure to keep some coals underneath the base of the crucible.

My Youtube channel: Cave of Skarzs

Just having some fun messing around with whatever I have a mind to do.

July 2, 2015
5:45 pm
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DaveTheGreat
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Just my $0.02 - the value of cans is usually more than the value of the aluminum in the cans. It may be way cheaper to just buy some scrap.

I had great results with an old trash can that I lined with a combination of water, perlite and fireplace cement. A hole in the side with a MAPP torch shoved in (pointing not straight in, but to the side so it swirls) was enough to melt enough to make several ingots the size of cupcakes (in fact, I used cupcake pans to make the ingots. Great way to turn a bunch of loose scrap into orderly storage, if nothing else). 

July 9, 2015
7:16 am
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chewmanfoo
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Thanks everyone for the reply's!  I'm excited to get started - and since the weather in Texas has been mild, it might be bearable to run the forge during the day.

My first task is to figure out how to grind aluminum cans into flakes.  I bought a wood chipper - I'm going to work with it to turn my bags and bags of coke cans into a big barrel of aluminum flakes.  Wish me luck!

July 9, 2015
10:57 am
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Morgan A. Kirk
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O____o

  Good luck. I would have suggested just cutting them into strips, but they'll probably melt better as flakes.

My Youtube channel: Cave of Skarzs

Just having some fun messing around with whatever I have a mind to do.

July 9, 2015
7:35 pm
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DaveTheGreat
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I suggest using an absurd amount of flux, and a reducing flame if possible. A lot of the mass of a can is already aluminum oxide just by virtue of it being almost all surface area with little internal mass. By absurd, I mean literally an entire box of Borax. 

The first part of the melt was the hardest bit for me. Once you have a small puddle of aluminum in the bottom of your flask/crucible/whatever, then you can feed pieces into the puddle one at a time. That minimizes the contact with the atmosphere and the solids melt from within the liquid. Less dross, less waste. You can also start with just borax and then submerge the aluminum in there once it melts. 

If you throw a pile of loose strips in there, you may wind up with mostly Al₂O₃, which can be darn handy for making your own abrasives or putting texture on your porch so you won't slip in icy weather, but it's nearly impossible to burn off that oxygen once it's bound to the aluminum.

Another cool thing you can do is make your own aluma-bronze. Feed copper wire into the molten aluminum and watch it alloy (depending on the wire and the temp, you may even see the copper wick up the aluminum faster than you feed it. Looks awesome). Try a fairly thick-ish gauge and keep feeding it in until the alloy's melting point changes so much that the whole thing freezes. 

Have fun! 

July 14, 2015
2:00 pm
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Scott Rash
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If you already have a forge, here's a low-budget, easy approach (no furnace, crucible, or crucible tongs needed).  Find a long-handled blacksmith's ladle.  I've picked them up at garage sales and antique stores for around $10.  These were always used to melt lead, so heat it up a few times to a high heat so it scales off all of the surface.  Best to do that outside, and don't stand by breathing lead fumes! 

I have a gas forge, so adding little bits of cans wouldn't work very well.  I put a few chunks of 1" aluminum bar offcuts I bought at Alaska Copper and Brass for next to nothing into the ladle.  The chunks of bar puddle after a few minutes in the forge.  Leave it in the forge for a minute or so after the aluminum puddles.  Scrape off any dross and pour.

DaveTheGreat is right about using a reducing atmosphere, but I've found that under normal conditions there isn't a whole lot of waste due to dross.

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