I have no reason to do this at the moment, but I am just curious. Does anyone have a video on how someone would go about making a metal coin? I have no special equipment or anything. I'm not sure if there is some easy way of doing this, but I thought it would be interesting to learn how (if there is a DIY way)
Coins may not be the best example as from at least viking times and possibly before they were not cast but stamped with dies and have been ever since.
Historically buckles for clothing and belts were cast, also pilgrim badges cast from pewter using a carved stone mould.
Using this method a skilled craftsman can make complicated 3d shapes.
Craig
or you can use sand to make the mold and use metal to fill with
It also depends on what you want to cast with. Something like pot metal (not really sure what the makeup of this is but I'm guessing it would be high in tin) or lead which both have a low melting point are easy to pour and cast using either sand or a one use plaster mould (you carve or mould the master out of wax, pour plaster around it with a fill hole, put it in the oven upside down once dry and the wax melts out leaving a hollow area for the metal to fill, once poured you break the plaster and you have your cast).
Obviously to melt metal that is harder like brass, copper, bronze or ally, you need specialised gear and moulds made of casting sand.
I've cast sinkers for fishing from lead and it is pretty easy but never done any more sophisticated shapes.
There are casting silicones that can be used for casting pot metal. The silicone works the same as the RTV that is used for casting resin, but can be more expensive and a bit harder. Pot metal can be melted on the stove.
You can also "cold cast" metals. you do this by adding metal powder to a urethane resin. when you are done, the end product will be cold to the touch like metal and you can even file it and it will respond like metal. You can also coat the mold with the powder instead of mixing it in with the resin, however, if you do this then it will not be metal all the way through. It will save a bit of money tho, metal powder isn't cheap.
I looked into cold casting. and that does look cool. Probably not the best way to make coins though. I guess If i really wanted them id have to get them made. That whole double sided thing is a trick.
before you venture into pouring any metals in any form, get used to pouring hot materials in general. Ive seen people pour molten metal into molds that had some residual moisture in them, not nice.
Its very simple to cast up a coin in silicone. If its not a vintage coin or you dont care about the surface, use a dab of hot glue to hold the coin flat on a flat surface. Also get a couple hardware nuts (from nuts and bolts fame) and hot glue those around the coin. These will be your mold keys and lock the mold halves in place. Use a wax paper cup (cold drink cup) as the mold box and hot glue that to the flat surface with the already affixed coin in the center. Pour your silicone and side one is done. If your lucky the coin will snap off the surface and stay in the silicone to do side two, if not just realign it in place. Remove the hot glue, Vaseline the already cured silicone, use another wax cup pressed onto the mold half and hot glue it in place, pour your second half, done.
The trick and learning curve is in the pour. For metal I simply use a round sharpened hollow metal tube to cut a hole in one side of the mold. Usually on a raised surface or somewhere its easy to grind flat and polish away when removing the excess metal sprue.
What you should start with to learn pouring hot materials is simple, crayola crayons. You can melt them on the stove in a cut open soup can in seconds. It will pour like metal and is inexpensive to practice with. Use only crayola crayons though as cheapies and most other brands will not melt the same nor will they stay together most of the time when pulled from the mold.
For a gag I had to make silver coins that would melt quickly and pour into a bullet mold all in one shot. Crayons are the savior. Here are a few double sided crayon coins that were tests. The color is off but its the colors I had on hand for the tests. Its strait out silver crayons with a little silver metal powder in for nothing more than a metallic look when melted. I let the mold cure in the fridge since these had to be done in minutes.
Real coin on top left, crayon coins on the right, lower left is a coin I poured in plastic.
You can still do it in your backyard, it's actually a lot easier to melt those metals then one would expect... I'm not saying copper and bronze is a cake walk but it's not overly hard... It's that small extra temp needed for metals like cast iron that poses the biggest challenge as they exceed the temp of most of the foundry cements that DIY kilns are made from, thus the kiln melts before the metal melts...pfillery said:
My brother and I actually melted a kiln attempting to melt cast iron, the graphite crucible was floating on a layer of molten foundry cement as the kiln melted around it
Anyway be safe, there is nothing safe about it even if you are being safe...
BTW her is a video of use giving a new "large" kiln it's first run with copper, there is about 6 or 7 pounds of copper in the crucible... The machining blanks we cast where 1.75" in diameter and about 5" long...
Same video two different formats
http://rpf.exoray.com/melting metal.mpg
http://rpf.exoray.com/melting metal.flv
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