BB Video: Carve Steel with Saltwater, Electricity and a Tin Earring (Popsci)

(Download / Watch on YouTube)

Boing Boing Video teamed up with Theo Gray and Popsci.com to produce this video that demonstrates how you can mold steel with electrochemical machining, using a soft, cheap piece of tin -- without any physical contact. Theo is the author of the book Mad Science, in which many other experiments like this are featured. Theo says:

I remember seeing a demonstration of a seemingly magic process at an engineering open house decades ago, in which a soft metal bit carved detailed shapes into far harder metals. It's called electrochemical machining (ECM), and it's so simple in principle that you can do it at home with a drill press, a battery charger and a pump for a garden fountain.

ECM is basically electroplating in reverse. In electroplating, you start with a solution of dissolved metal ions and run an electric current through the liquid between a positive electrode and the object you want to plate (the negative side). The ions deposit themselves as solid metal onto the surface of the object.

Read the whole HOWTO over at popsci.com: Carve Steel with Saltwater, Electricity and a Tin Earring

Image below: "The tin peace-sign earring acts as an electrode, etching away the metal in the hardened steel washer [left]. The imperfect results are due to the difficulty of manually maintaining an exact thousandths-of-an-inch distance between the two. Commercial electrochemically machined pieces, like this microturbine for a water pump, use sophisticated electronics to monitor the current flow and carve precise pieces [right]. (Courtesy ECM Technologies BV/ ECM Productions BV; Mike Walker)

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Discuss

6 Responses to “BB Video: Carve Steel with Saltwater, Electricity and a Tin Earring (Popsci)”

  1. Anonymous says:

    I really really hoping that I could build the same ECM machine as this video but I don’t know how to specifically arrange the circuits. What is required and how should I hook them up?
    Please help me..

  2. Anonymous says:

    I really really hoping that I could build the same machine as this video but I don’t know how to specifically arrange the circuits. What is required and how should I hook them up?

  3. Jake von Slatt says:

    This is an interesting process! It’s basically the same thing I used here: http://steampunkworkshop.com/electro-mach2.shtml but I have also seen rigs very similar to the one pictured in the PopSci article used to gently erode away steel bomb casings for disarming unexploded ordinance.

  4. CaptainLudd says:

    See also EDM (electrical discharge machining). I got to play with one in a college metal shop class and was able to drill a 3/8″ square hole through a hardened steel ball bearing at an angle. It uses a graphite electrode instead of tin and the fluid acts more as a flushing agent then as an Ionized medium. The down side is there is electrode wear (sometimes tricky to calculate when precision is needed) and the finish is not as smooth. One of my classmates used it to burn a new internal axle spline into the hub of a tractor that he was restoring. Impressive stuff.

  5. pinehead says:

    Now that was pretty cool! I wonder how difficult it would be to build a more precise home version, similar to the homemade CNC machinery people have figured out. I’ll have to explore this further.

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