Crédits:
How to recycle scrap metal in the backyard, with a homemade, Mini Metal Foundry.
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Note: The contest for the sword is CLOSED. The winner is Anthony Wagner from Virginia who guessed 690.2 grams. The actual weight was 691 grams. Congratulations Anthony! (http://bit.ly/WinTheSword)
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Project inspired by: This foundry is an original design, which comes after months of experimenting, and over 10 different prototypes. The functionality is founded on ideas I collected while searching the internet for foundry designs.
WARNING: Charcoal foundries can reach temperatures in excess of 1,000ºC, which is well above the melting point of hobbyists. This project should only be attempted with adequate knowledge and training, proper protective safety gear, and in a fire resistant area with adequate ventilation. The sparks flying from the foundry can ignite fires, and the fumes from burning dross can be toxic. Use caution and common sense. Use of this video content is at your own risk.
Background:
For as long as I can remember, I've been intrigued by the idea of melting metal and making things with it. The problem has always been that it was out of reach or required really expensive equipment.
In this project I experimented with 10 different prototypes, to develop a reusable backyard foundry that melts aluminum soda cans easily and safely. I tested different refractory recipes, different containers, different setting for blowing air, and different types of makeshift crucibles.
I tried various ratios of portland cement, sand, perlite, plaster of paris, water, and even kitty litter. For containers, I experimented with clay pots, plastic buckets, no container, cinderblocks, and a galvanized steel pail.
I ended up favoring the galvanized steel pail, and a mix of 50% plaster of paris, and 50% play sand, by volume, which was inspired by a video by NightHawkInLight "How to Make a Soup Can Forge" http://bit.ly/IBSoupCanForge
Depending on where you get, or find, your materials the cost can range anywhere from $5-$25 per unit. With the materials I used, I was able to make 2 units for under $40 ($20 each). Even on the high end, this is probably one of the cheapest, reliable, backyard foundries that can be made.
I used mine to melt soda cans, and extract the aluminum for future metal casting projects. All the soda cans came from a local recycling depot. I bought back 30 lbs from the depot to avoid having to drink gallons and gallons of soda. :) I stored the ingots in various forms, which you can see in the next video, and tried a cool technique for making a little sword by pouring liquid metal into a bucket of sand. I'm planning to make a project video on how to do that in the near future.
The purpose of my backyard foundry is to demonstrate the most basic setup for casting metals. However if you plan to attempt this approach yourself, some important things to consider beforehand are as follows;
- Soda cans work really well, however aluminum cans are one of the worst sources for aluminum to cast with, and some soda cans in the UK are actually made of steel. The alloy was meant for extrusion, so is not the best for casting. They also produce more dross (slag) because the thin walls oxidize quickly and the plastic coatings on the cans add impurities. A better source of aluminum for casting would be cast aluminum items from thrift stores, like electric skillets or small engine blocks from lawnmower shops.
- The crucible I used was steel, but it’s important to note that steel can be soluble in molten aluminum. It’s possible that when you lift the crucible out of the foundry, the bottom can dissolve out and drop molten aluminum onto you feet and onto the ground. A good refractory crucible can be purchased for about $30 online.
- Lastly, casting over concrete poses risks of steam explosions. If molten aluminum falls to the ground, it can superheat the moisture in the concrete and cause it to spall (steam explosion) where the aluminum lands. This can potentially send hot concrete and molten aluminum spraying everywhere. When possible, melt and pour metal over sand to minimize risks.
Note: Wearing polyester gloves like the ones I had in the video is risky because the material can melt into your hands if you get splashed by hot aluminum. This can potentially leave burns where the metal lands, ringed by plastic burned into the skin.