Let’s melt metal in the backyard!
Yeah, that teensy-weensy little pool of molten metal in arc welding was cool, but it was time to move up to the next level. A big glowing pot full of silver liquid awesomeness. Oh, yeah.
I have been reading about other people’s exploits in melting metal and sandcasting with it for a year or two, both in books and on various websites. It all sounded rather complicated and intimidating, until I came across a particular Instructable on the Pizza Sauce Can Furnace. It advertised “Melt Aluminum for $3 and some begging!”, which just coincidentally matches my ideal price range.
By all descriptions, aluminum was one of the easiest metals to start with, and is certainly readily available as scrap. It was my first objective.
I made a simple foundry furnace using two steel cans, one inside the other with a little air gap between them. Not an efficient furnace, but a simple proof-of-concept. I punched some holes in the bottom of the inner can, filled it with charcoal, and blasted it with some air from the shop-vac blower. And guess what? Yes, it proved the concept.
I melted some scraps of aluminum in a tin can from the kitchen. That tin can is a “crucible” in fancy-pants foundry talk, and it’s not actually tin, it’s steel. But it is also thin steel, and the charcoal got so hot with that shop-vac blower, that it burned right through the can. The funny part was that I didn’t know right away that it had burned through. Because the can was surrounded by a pile of coals, I couldn’t see the sides. But I could see inside, and I got a nice gleaming silver pool of molten aluminum filling part of the can. So I started adding more aluminum into it, to fill up the can. It was amazing how much I could add to that can and not fill it up. It was a magical can. I could just add, and add, and add, and add more aluminum…. Until I finally got a clue and realized that it had to be going somewhere.
I dumped the tin can (ahem, I mean crucible) of aluminum into a simple mold I made from a piece of steel angle-iron, to get a nice triangular bar. That’s an “ingot” if you are one of those fancy-pants foundry guys. After the charcoal cooled, I found the secret magician’s trap door where all my aluminum went from my magic crucible. Under the coals, between the two steel buckets, was strange rounded chunk of aluminum. Oops, rather, I mean, look at the fascinating sculpture I formed from my special aluminum drip art process. Yeah, that’s it… Yeah…
The shop vac was too much, so I replaced it with an old hair dryer, which was much better. I also replaced the air-gap steel bucket with a better fire-brick bucket. More on that to come later.