Starting off with a foundry : Initial tools

The first step in my tech tree is to be able to form and cast metal components. Being able to do this will allow me to produce components for almost every single manufacturing tool that I hope to produce as I move up the tech tree to perfecting a micromanufacturing laboratory.  It became obvious early on that an aluminum foundry would be a great start. After a little research I had decided to build my own foundry setup.  I usually post on craigslist whenever I start a big build operation in the hopes that I'll be saved some effort in the end, and the foundry hunt really paid off!

I was emailed about a local high school decommissioning their entire metal working lab. They offered me their foundry, 2 control stations, 6 crucibles, steel tongs and stirring tools, 26 steel sandcasting flasks, gauntlets and gloves, and a pyrometer.  This offer was taken and the foundry operation hit the ground running.

Furnace and Accessories 

Furnace with Control Box

The furnace and control box where both mounted onto carts so the entire arrangement can be wheeled outside. The sheer amount of toxic fumes released during the melting of metal completely removes the possibility of using the foundry inside.

Inside of the Control Box

As you can see the control box comes with two different main components. There is a fuel intake line, which consists of a regulator, a solenoid, and a limiting ball valve. The other component is a large high rate blower. These two components meet in a black iron T and then exit the control box. This particular unit has an IR eye that detects the status of flame in the furnace and sends signal to the control circuit to shut off the fuel feed by closing the solenoid.

Ignition Plug

The furnace is ignited by electricity being sent into this plug. When inseted into the foundry the protrusion is centered in a steel O ring. The spark is actually a field of energy that fills the gap between the post and the O ring.  The negative connection on the circuit is run along the steel fuel tube that connects the control box and the foundry. If the ignition AND the fuel tube are not connected do NOT provide power. Shocked the shit out of myself figuring that one out. 

One of the crucibles

The included crucibles are all constructed of graphite and vary from a size 6 up to the pictured monster, which is somewhere around a gallon in maximum capacity. They are extremely heat tolerant but cannot handle impact, so they have to be treated with lots of care. When they get hot, they glow red and are somewhat terrifying(ly cool).

It took a few test fires to figure out some basic rules. Here they are.

• Never heat up a crucible without a charge (a charge is metal for melting)
• Heat the furnace up for 10 minutes before placing the crucible inside
• Foundry should be ignited with air feed at near-max and fuel at near-minimum
• Fuel and air should be adjusted until a flame exist the top of the furnace with a constant shape
• Flames that 'lick' and flicker indicate too high an air content
• Flames that do not exit the top of the furnace indicate too high a fuel content

Furnace, Control, Fuel

We discovered over time that we absolutely had to partially submerge the LP gas tank in order to keep it from freezing up. As you can see in this image we have scrounged up steel carts to serve as platforms for  the foundry operation. Assembly of the entire thing now takes about 20 minutes, which we feel is pretty good.

DIY Options


A foundry setup is pretty simple to piece together, you just need a few different things.

Refractory cement is a form of cement that is designed to handle extremely high temperatures. The inside wall of a furnace needs to have very thick walls of refractory. Ceramics, concrete, and stone are all common refractories. This is a really good design for a simple furnace, and there are TONS of different materials you can use to line the wall.

One interesting option I was considering are factory smokestacks. These giant tubes are lined with extremely high grade ceramic insulation, meaning that a length of one is almost a perfect foundry body. Just add a welded bottom plate and pour enough refractory in to make a base.  I also was looking into designs for building a bench foundry which is like a liquid metal coffin.  If I ever have a permanent operation this is probably what I will do in the end.