Activities on these pages about foundry work are very dangerous. The chances of having a fire, causing injuries, or even dying are very good if you are not careful. I am not a professional foundryman, and will not attempt to disclose all hazards. If you choose to try this hobby, every precaution must be taken to be safe. Remember, a hobby is only fun until you're standing in the middle of the street with your family watching your house burn.

When building a foundry, it is necessary to make a few tools also. This page shows how I have made a couple of tools for my foundry.

Ceramic crucibles can be bought, but they can get expensive if you break them. I make my own crucibles at work from 10 gage (0.135" thick) black iron. I start out with a piece 6-1/2" by 16-1/2", which gives me a crucible that is 5-1/4" in diameter and 6-1/2" tall.

After shearing the metal I roll it. We have a power roll at work that has 4" diameter rolls. The 5-1/4" diameter is about as small as you can get with this roll. And 10 gage is too thick for a hand roll. To make the bottom I cut out a 5-1/8" diameter circular plate.

I then weld the seam on the body, and weld the bottom to the body. These welds have to be very sound, so I use a wire-feed welder, and then go over any spots that I don't like with the TIG machine. I have also made crucibles out of stainless steel, which I just TIG weld. (Click here for an explanation of the welding terms.)

A pouring spout has to be put on the crucible. An area of the crucible can be heated with a torch and a lip forged. What I like to do is to lay out a spout. The spout will stick out 1" from the body, and it is 1" wide at the top. I lay it out as two similar triangles that are mirror images. This method doesn't take the curve of the crucible body into account, but it's close enough since it is welded inside and out.

After the spout is formed I trace it on the crucible and cut it out with a plasma cutter. A plasma cutter acts like a cutting torch, but it uses compressed air and electricity instead of acetylene and oxygen.

Here is the finished crucible. Well, almost finished. It still has spatter on it from the welding, but this is easily removed with a putty knife.

When you have a crucible full of molten metal, you need something to lift it with. The tool for this is a pair of tongs. There are several different types, and each type has its use. The tongs that I use for the charcoal furnace were designed to lift the crucible straight out of the furnace. The design of the propane furnace makes it difficult to use them. That's why I made a new pair.

To lift the size crucible that I use I needed two pieces of 1/4" x 3/4" bar stock. I drilled a hole at the pivot point and installed an iron rivet. Then I put the pieces in the vise with the pivot point above the jaws. Then I heated the metal with an acetylene torch until it was a dull red color, and bent the pieces with an adjustable wrench. It may seem that the hotter you get the metal the easier it will bend, which is true, but if the temperature is too high the metal will rip instead of bending. In the picture above I'm heating the metal. You can see the red color in the bar stock at the jaws of the vise.

In this picture I'm actually making the bend. The bars are bent 90°, and they act like a pair of those doohickies that you use to take corn on the cob out of a pot. (Sorry about the use of kitchen jargon in a workshop page.)

Boy, I need to get the camera set up right. I decided not to bend the end of the tongs to fit the crucible, but to form jaws for them. So I bent the bars out a little less than 90° and then bent them again to straighten them out.

Here you can see how I set up the tongs to weld. I took a crucible and set it on the table. Then I put the jaws around the crucible, and closed the tongs on the jaws. The cabinet clamp is holding the tongs tight. I wanted the tongs to be at an angle, so I elevated the handles. A few welds and they were finished.

Wire welding is a process where wire is electrically charged as it is is fed out of the welding gun. When the wire hits the metal it arcs, which heats the metal to the point where it melts. The weld must be protected from the air, so an inert gas is fed along with the wire. This process is also called MIG, metal inert gas, or GMAW, gas metal arc welding.

TIG welding uses an electrode made of tungsten to make the arc, and an inert gas is used to protect the weld from the air. When the arc is established and the base metal is melting, filler rod is fed into the puddle of molten metal to form the weld. TIG stands for tungsten inert gas, and the process is also called GTAW, gas tungsten arc welding.

So, what's an inert gas? An inert gas will not react with another substance because the valence shell of electrons (the outside shell) is full. Chemical reactions take place in the valence shell. Gases such as helium and argon have a full valence shell, and the atoms in carbon dioxide (CO₂) have full valence shells because of electron sharing. These three gases are common in welding. [See Dr. Lonadier, I was listening.] Click here to return.

Updated September 8, 2002

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