How to Set Up and Run a Casting Furnace




I did this at TechShop Menlo Park!
Casting is a ton of fiery hot fun! Once you try this you will never stop. It is dangerous though so properly assembling your equipment is essential in an effort to keep your face and other body parts. This is what you'll need to do:

Step 1: Furnace

Check out your furnace, make sure to clear out any debris and set a refractory brick  in the middle of the inside. The brick will serve as a shelf you will place your crucible onto.

Step 2: Propane

Get a full tank of propane as running out of gas in the middle of your process is really sad. Place the propane tank as far away as possible from the furnace to prevent the heat from getting to the tank. You can imagine the tragedy that would cause so make sure to remember it! Then screw in the gas line to the propane tank. This end of the hose will have a regulator on it. The other end of the line screws into the opening located right next to the venturi air vent lid. 

Step 3: Gas Flow

Open the propane tank with the valve on top. Open the regulator and keep in on high. You will need a substantial amount of fire in order to keep it going once the air is introduced. Open the line valve with handle located close to the furnace end of the line. 

Step 4: Ignite!

With your gas line open and the venturi air vent lid closed light the fire! You can use a match and throw it in the furnace, I like to use a map gas torch as it allows a little more space between me and the ignition of a large fire. The fire should be big and come up to about chest height.

Step 5: Introduction of Air

With the air vent lid closed plug in the motor. You will hear the motor running but it will not affect the fire until you open the air vent lid. When opening the vent lid do it gently, and just a little bit at a time until you hear a big Hwooosh sound resembling a jet engine. This is the sound you're looking for: it means the fire is circulating inside your furnace ensuring even heating of the crucible. 

Step 6: Melting Metal

Aluminum has a low melting point so it is fast and easy to melt. Use aluminum scraps of whatever kind you can get your hands on. Smaller pieces arranged with some space around them are much faster melting then a big hunk of it. When closing the furnace lid use a metal pole and do it from the sides ( it takes two people). Be careful when looking at your melting metal through the peephole on top of the furnace lid. Your eyelashes and eyebrows are the first to go.

You are now ready to use your imagination and creativity and pour molten aluminum into the molds of your choice. See investment casting instructable  for assistance in this portion of your project.



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    11 Discussions


    1 year ago

    What about ceramic cruicible?

    John T MacF Mood

    2 years ago

    What's the high end of the temperature range for this set up? Been wanting to learn aluminum casting (use those damned SC fire ant hills to make beautiful trees, and kill the ants!), and move up to iron, making cast steel tools, anvils, and such. Do you think that high carbon steel might melt in your crucible? (1.25% to 2.25% carbon) - for tools and anvils. It has to be hardenable, not mild steel.

    Trike Lover

    6 years ago on Introduction

    Some further information on the (castable?) refractory material used in your furnace would be useful - particularly the specific material used and where you got it. Also some information or pointers to the particular burner design used (Reil burner, for instance, or one of Dave Gingery's designs? The final item that would probably be of use to a beginner would be a source for suitable crucibles, and also some pointers on how to handle them.

    Pouring molten metal, whether lead, aluminum, or iron are procedures that require much preparation and attention to the details of keeping yourself safe from the various mishaps that can occur. Every year people are injured when their crucible cracks, their mold lifts during a pour, or the rivet come out of their home-made tongs just as a full pot of molten metal is being moved from furnace to pour. Proper clothing and gear is a must.

    A nice instructable with some good pictures - my points above are things I hope you will consider adding in the future.

    4 replies

    Dear Trike Lover,
    Further instructables relating to the use of the furnace are being written by me. I thought safety gear and pouring tools deserve instructables of their own. Thank you for suggestions. This is NOT and instructable about how to make one at home and I highly discourage using improper tools. I teach casting at TechShop Menlo Park and I suggest taking a class, using our proper eqipment and calling on me to assist you in every project you're making, to keep things safe.
    :) Miss Cabbit


    Dear Miss Cabbit,
    Thank you for your thoughtful reply. I'm very glad to learn that you are preparing further instructables on safety clothing and gear, and pouring tools.

    Unfortunately, I live several thousand miles north of Menlo Park, and alas, will not have the pleasure of meeting your good self anytime soon.

    I have cast aluminum in green sand moulds ever since the 1970's, after reading Dave Gingery's books on building a metal lathe and accessories. I also cast lead for bullet making, as I am a long-range competition rifle shooter.

    My first furnace was charcoal fired; I later switched to a gas burner patterned after Ron Riel's designs. I later discovered and joined a local "meltalcaster's guild", who operate a cupola for casting iron as well as crucible-melting other metals. The Guild is fortunate to have as members several retired master foundrymen, who can guide newcomers along the safe and correct paths. "Newbies" are not allowed to do anything but watch for at least two seasons of iron melting - and rightly so!

    I would agree with you that an excellent first step for anyone contemplating home casting is to take a course at a local technical college, or else join an organization like the "metalcaster's guild" if no course is available nearby.

    Having made my own mistakes during my initial learning phase, I am perhaps overly emphatic that Safety, Safety, and Safety are the most important concerns at any level. I did not mean to take away from your excellent presentation in any way. I look forward to your next Instructables.


    Hey, I added some instructables to go along with the casting furnace one. I included your suggestions. Thank you!


    Thank you! Wow you sound interesting and full of great knowledge. I wish we were closer and could spend some time with different methods of casting. Please do follow my instructables to come on sand casing, lost wax, pouring, safety, etc.. and let me know if I am missing something or could improve something. I do appreciate constructive criticism especially with something as dangerous as casting. :)

    TechShop Menlo Park actually does have a casting furnace. The one pictured here is actually the one available at TechShop.

    Dear Moonbeam! Come down to TechShop Menlo Park and I will be more then glad to tech you how to use the furnace. Let's play! It's way fun!!!