A homebuilt crucible for the casting furnaceI built my crucible more or less as Dave Gingery suggested, out of steel pipe. I used a 5" length of 5" pipe, wall thickness maybe 1/8", and it's lasted through a hundred or so blasts. I welded a piece of the same steel onto the bottom; the welds have not lasted so well and have broken several times, giving me slight leaks. This can be exciting.
I also added a feature to the crucible: a handle. I welded a piece of 1/4" square rod onto the top, in an arc, to form a sort of steel bucket. I really like this because it allows me to remove the crucible from the furnace with a hook, then grab it with tongs that are somewhat like scissors, which are positively retained because of the bottoms of the handle stick out from the sides of the crucible, and when I pour, I pour from the side. Gingery's design, which is not bad, calls for tongs more like pliers, which you stick down into the furnace from the top, grab the crucible, lift it out, and pour staring down into the crucible. His design has the distinct advantage of being much easier to load the crucible; while I can fit piston heads into mine it takes a little bit of work.
Other good options are buying clay, graphite or silicon nitride crucibles (budget casting supply sells these) which will absolutely not spring leaks, and are capable of melting copper and cast iron, but are also quite a bit more delicate than my crucible. They also require tongs which are shaped to match the crucible form. They also cost a LOT in comparison to my crucible. But they don't require welding.
My tongs consist of two 1/4" steel rods about 3' long, with a rivet partway along them, and the ends curved to match the crucible. Pretty simple. The first time I built them I used an old nail as the rivet. It sheared while I was holding a crucible full of molten aluminum. This wasn't the best thing ever. Now I use a concrete nail, which is hardened steel; it should last.
This page written on 12/15/00, last modified 123 May 2023.
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