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Is it possible to do coining on small scale

  1. Nov 11, 2007 #1
    I would want to create medals is it possible to do this on a small scale
     
  2. jcsd
  3. Nov 11, 2007 #2

    FredGarvin

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    Using what process? Stamping, forging, molding?

    You can do anything you want if you have enough money and space.
     
  4. Nov 12, 2007 #3
    What would I need to make the die n especially engrave the design in it .
     
  5. Nov 17, 2007 #4

    Danger

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    Welcome to PF, Selseg.
    You should be able to use the 'lost-wax' process that most bronze foundaries have, but on a smaller scale.
    Carve the medal as you want it out of wax.
    Poke a small hole in the bottom of a tin can, with a slender piece of stiff material such as piano wire stuck through it to an inch or so.
    Pack wet sand around the wire to just even with the top of it.
    Place your wax model on top of the sand, just touching the wire.
    Pack more wet sand around firmly around and over the model, with another piece of wire in contact with the top of the model and sticking up past the top sand.
    Hold the can solidly with a set of tongs or pliers, pull out the bottom wire, and heat the can with a torch. The wax will melt and run out the bottom hole, leaving an exact imprint of the model in the sand cavity.
    Stick the bottom wire back into place and pull out the top one.
    Pour your molten metal into the top hole and leave the whole thing to cool.
    Once it's set, dump the whole works out and collect your medal. There'll be tiny imperfections called 'sprues' where the wires were, much like those on a plastic model part when it's removed from the 'tree'. Touch them up with something like a Dremel or a small file and a buffing wheel, and you're done.
    Since I don't know your age, I will assume the worst and encourage you to be extremely careful when dealing with anything that hot, and particularly with an open flame when wax is present.

    For an easier and safer, but lower-quality, process, you can make a separate mould for each side (1/2 of full thickness) by sticking your model into plaster of paris. When it's hard, pack JB Weld or other metallic epoxy into the moulds, then bond the two halves together after they're cured.
     
  6. Jan 28, 2008 #5
    Thanks, If I use the lost wax process wont it take me a long time to produce 'say 100' medals or more .
     
  7. Jan 28, 2008 #6

    Danger

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    It will if you do one at a time. You can, however, use a wider container and multiple models. There's also the option of combining the processes. You could make multiple imprints of your model in sand one side at a time the same as you would for the plaster mould, and bond the two halves together after pouring.
    It might even be possible to use metal pouring with a plaster mould, but I don't think that it would withstand the heat.
     
  8. Jan 28, 2008 #7

    jim mcnamara

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    You cannot use coarse play sand, the resolution is way too fuzzy for a medal with writing on it, for example. Go to a jeweler's supply house and find casting supplies. Casting sand comes in different particle sizes - you need something fairly fine. There are also bonding agents for sand casting, and high temp casting plaster, too, which would be even better than sand. With plaster molds you could produce 10 or more medals per hour. Once you figure out how not to kill yourself while playing with molten metal.
     
  9. Jan 28, 2008 #8

    Danger

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    Thanks, Jim. I wasn't aware of high-temperature plaster. And again my sloppiness showed in not pointing out that you can't just go down to the beach and collect a bucket of sand. I really have to start paying more attention to what I'm saying. :redface:
     
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