Looking to start a backyard foundry

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DH (retired shop teacher) sez:
One thing I haven't heard mentioned is the use of a lead pot for melting the aluminum. When I was in Junior High with my Dad the metal shop teacher and years later when I taught at another school we used a lead pot. (ETA Lead pot is a cast iron pot used to melt lead by plumbers & for pouring bearings, etc.) The aluminum was melted in a cast iron pot using an open gas burner. The pouring was done using a ladle dipped into the molten aluminum.

Another factor is flux (ETA flux cleans impurities out of the molten metal.) My Dad never used it but we used it in college and in all the shops/schools where I taught. It came in tablet form and when dropped into a pot of molten metal it off gassed something fierce. Cant remember what the flux was made of. Schools threw out this equipment for the most part. Getting hands dirty from petrobond sand was not fashionable for suburban kids

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Cindy in SW PA

Now that flux has been mentioned I do tend to remember that we used something, and I think it was a small amount of borax.

As to dealing with moisture, once we fired the foundry while it was coming up to temperature we set the pistons on top of the lid so that the warmth would evaporate the moisture out of them.

We would then add a few at a time to turn molten while the next batch heated the moisture from them.

Once the flux was added we used a ladle to scoop out the wrist pin holders and other metal non-aluminum parts such as broken ring pieces, etc. Seems that there was always a fair amount of it. The leftover aluminum from a prior pour made into ingots was our favorite to use since they didn't contain all of the junk.

Magnesium was another danger we were warned of. It was our understanding some of the pistons had a higher quantity of magnesium in them than others and it created a greater danger of explosion.

Fun to try to remember all of this stuff from nearly 50 years ago. BTW, our foundry was LPG fired with a small high volume blower providing swirling heat around the crucible.

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My family---bEI

I built a kiln and cast bronze in college.

Try one of the "Smoothe-on" mold making products, two part rubbery compound. Make a two or more part mother mold out of this stuff. Fill the mother mold with molten wax, suspend the wax in a tube of plaster. Melt out the wax in something like a seven hundred degree kiln, this does two things, it allows you to recover the wax out of a drain hole in the bottom of the kiln, and it cooks out all the chemical water in the plaster making it easier to break your casting out of the mold and allows you to reuse the plaster.
casting is fun.

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The best of men is only a man at best.

Ted;

Go to the http://www.backyardmetalcasting.com website, and read most of it. You'll have fewer questions, or at least a better idea of what questions to ask.

The most common method of casting is sand casting.
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take a look here, and you'll have a good idea of what people are talking about:
http://en.wikipedia.org/wiki/Sand_casting

Michael