A SMALL electric arc furnace for experimental purposes can be made from two flowerpots, one 2 in. in diameter and the other either 6 or 8 in. Drill two holes opposite each other just below the lip of the smaller pot. (An ordinary steel drill will do this.) Make them large enough to receive carbon arc-light rods.

Cover the hole in the bottom of the large pot and fill with sand until the top of the small one, when set firmly on the sand, is about 1 in. below the top of the large one. Now drill a hole in the large pot at the same level of those in the small one. Push a rod through the three holes and mark the point of contact on the other side of the large pot. Be sure that the rod is level and the small pot is properly centered. Drill the second hole in the large pot and push the rod through it. Now pour sand around the small pot nearly to the level of the rod. Settle this by pouring a little water on it. Pack fire clay around the rod in the spaces between the two pots, being careful to get it close to both walls. This keeps the sand from jamming the carbons, which must slide easily. Pour sand even with the top of the small flowerpot and settle it with water. Withdraw the rod and set the furnace aside to dry. Lids may be made from flowerpot saucers.

Prepare the carbons by clamping a strip of brass or copper around each to furnish a good electrical contact. Tape a piece of glass tubing to one rod for adjustment as illustrated. The other rod should be held rigid while operating. The necessary resistance can be made by putting a teaspoonful of soda in a gallon of water. My furnace draws current through a 15-ampere fuse, which is safe for ordinary house wiring. To start, touch the carbons together.

Dark goggles must be used. Do not touch the carbons with the bare hands. Do not use a resistance of the type described when it is hot enough to boil.

  1. avatar28 says: August 3, 20076:39 pm

    I DID this with a friend several years ago. He ended up burning his retinas or something. He basically had to lie in nearly complete darkness for a couple of days until they healed. He said that any light at all was just a horrible stabbing pain. Glad it wasn’t me, though no telling what damage I did myself.

  2. Redemerald says: May 7, 20085:19 am

    Excellent knowledge, dangerous but to a welder highly understandable. Such a device is what a small time refiner and reclaimer of Platinum Group Metals could definitely use with repeated warning on eye protection. The new masks would take care of that danger as long as one does not get forgetful. Getting “sandeyes” from welding arcs is bad enough but CA is even worse that that oor even direct solar viewing. Thank you for that artical I believe one named Nicola Tesla came up with the original idea way back when and for the most part is no longer common knowledge but it soon will be again now that precious metals are going upwards at a phenominal rate because the world is on the verge of return to metal backed currencies and the so called fiat or unback ones that we have been forced to accept since 1913 when the FED came into being along with all the other central banks of this greedy world. Cheers! Redemerald

  3. Bob says: September 30, 20081:46 pm

    I built this exact arc furnace from the original magazine when I was a kid (i am 78 years old now) and i used 1/2 of a toaster element as the series resistor. It worked fine. I did use a lid over the top and welding goggles on my eyes. I melted some copper wire and then added some zinc to the molten copper. The zinc flared up with white smoke. When it all cooled i had a piece of bronze about the size of a nickel, more or less. Had to cease operation of it after my father received the months electric bill. The resistor was probably around 6 Ohms or so and therefore the furnace was drawing close to 20 amps.

  4. Joe says: January 31, 20094:09 pm

    What I don’t understand is how he gets the crucible out unless the crucible sits on top of the inner pot. In other words is the small flower pot the crucible or does a crucible go in on top of the inner pot.

  5. jayessell says: January 31, 20097:08 pm

    The electrodes are withdrawn before the inner pot is removed.

  6. Sadhan paramanik says: April 29, 201110:50 pm

    i want make a small furnace for making SiMn production at home

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