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Handy for arc experiments, Popular Science 1933

HEAT so terrific that no known substance is able to withstand it for long can be developed in your home laboratory with nothing more than a pair of electric light carbons, a small crucible, and some means of controlling the flow of the electric current from the house mains through the arc.

Most electrical experimenters attempt to use an old toaster or electric grill in series with the arc. This works all right, but the current flow is limited to three or four amperes and is greatest when the carbons are in contact and the arc is producing the least amount of heat. Adding another toaster or grill in parallel with the first one doubles the current through the arc, doubles the cost of operation, and still is open to the objection that the current flow is greatest when the arc is least effective.

The difficulty is that a carbon arc, operating on the ordinary 60-cycle, 110-volt current, actually requires only about 35 volts. The difference is wasted in useless heat from the grill or toaster.

Modern Mechanix » EXPERIMENTAL Arc Furnace MELTS ANYTHING – Link.

Phillip Torrone

Editor at large – Make magazine. Creative director – Adafruit Industries, contributing editor – Popular Science. Previously: Founded – Hack-a-Day, how-to editor – Engadget, Director of product development – Fallon Worldwide, Technology Director – Braincraft.


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Comments

  1. Mumbo says:

    Melts everything, including this guys retinas!

    Please remember safety glasses.

  2. grizella says:

    I did this using a cheap $59 arc welder from homier. I used carbon gouging rods (used for cutting metal thats too thick for a plasma torches or gas torches) for the electrodes. Instead of a crucible I used two bricks that I hollowed out with an air hammer to hold the molten metal. The bottom has large area hollowed out to contain the molten metal. The other one is a lid with two channels for the electrodes. Its got to be about the cheapest way to melt metal for small castings. Without the lid I wasn’t able to get the metal hot enough to pour into a mold thou. This is very dangerous and life threatening by the way. It has the potential to cause blindness, electrocution, burns,… to many ways to kill or permanently mame yourself doing this to list. Some things to note about this are the cheapo arc welder listed above came with a 220 volt euro plug that I had to cut off and rewire. I run it at its lowest (45 amp) setting for the greatest duty cycle(I wired it up to 110 once and it ran cranked all the way up to the 100 amp setting without the thermal protection tripping). The smallest carbon rods I found work best (1/4 inch). It also seem to help if I sharpen them and cut the copper coating off from the ends that are arcing. The carbons are kind of hard to find. I found them at the local farm and fleet store. My normal welding supplier did not carry them. The bricks do crack open after a while and drop the molten metal out so don’t do this on a table while wearing flip-flops. My metal of choice so far has been rusty nails for small casts to turn in my lathe. All the rust seems to get pushed out of the molten metal and the castings seem to be good all the way through as far as I can tell. This is sort of a micro scale version of the way scrap steel is melted back down.

  3. TheThompsonFive says:

    There just aren’t enough bow ties in science these days.

  4. supertim says:

    TheThompsonFive: I miss Bill Nye!

  5. TheThompsonFive says:

    Billy Nye was cool, but Beakmans assistant was a hottie. I think Bre should wear a bowtie for weekend projects.

  6. PaulTurkk says:

    Did one similar to this when I was 13 from a 1940s chemistry book…
    Used a saltwater rheostat ; 2 lead sinkers in a petri dish with salt water!!
    An old flower pot and carbons from some really old batteries.
    Blew the fusebox a bunch of times, and my eyes still hurt! Heh.

  7. Mumbo says:

    I had that book!

  8. John H says:

    I remember doing this as well. Per the book, I tore apart two D-cell batteries, removed the carbon rod from each, crimped each into a metal tube, used a terracotta flower pot for the crucible and a quick saltwater rheostat with washers for electrodes in the water. I remember the lightning bolts (arcs) jumping between those washers when the water got good and hot! Wasn’t very useful but a lot of fun at the time! :) If you remember, that same book told how to make an x-ray machine from old radio tubes. Thank goodness my buddy and I didn’t try that years ago or we’d still be glowing in the dark! LOL

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