Disclaimer: I'm not asking how to counterfeit coins or create an alternative to US coins (like the Liberty Dollar). Technically I'm making rounds and tokens. My question is, does anybody know of any resources (mainly web sites) on how to mint my own coins (I'm talking a single coin press, not a big production.) I was hoping there was a way I could use gears (I'm thinking an overall ratio of 1:200 (as in turning the crank connected to a small gear, say 1 inch 200 times will move the final gear by 1 inch. Not exact numbers here, but this is for clarification) If it helps, I'll only be minting on Copper (or brass or bronze) or silver (coin silver or .999 silver). I have the basic concepts down, and I would have to engrave the dies myself, but most of my "inventions" have proven that basic concepts give basic results. Thanks, Josh
I have a book that explains almost every way ever used from ancient hammered, modern and every way used in between...cant help you with websites though.
Here are a couple made by the coin dealer I go to.They are made of silver, the colour of the pictures is the result of my lack of photography skills. I can give you his e-mail if you want to talk to him about how he does it. Bill
Search for "shop press" in google. They're basically some steel I-beams and such with one of those hydraulic jacks. They seem to be available up to 100-ton. I'd think that making the dies would be the hard part.
We have a member that does this. Maybe he could help. http://www.cointalk.org/showthread.php?t=19411&highlight=shire
Making coins Hi Josh! Glad to hear that you're interested in making coins! It's quite a lot of fun. The very best book on the subject that I know of is THE ART AND CRAFT OF COINMAKING by Denis Cooper. He worked at the London Mint for over twenty years and the book is chock-full of great little details that you can find nowhere else. It's out of print and hard to find though, but I'm sure you can get a copy to borrow through interlibrary loan or perhaps the ANA library. There was a type of gear-driven roller press that was tested by various mints beginning about 1530 called a "Taschenwerke" (turning work) mill. But it had some significant problems, and with the development of larger and more powerful screw and knuckle presses the taschenwerke fell out of favour. A direct drive gear press is usually called an "arbor press" but they tend to be very light duty... between one and three ton force capacity. It doesn't help to make a very powerful gear reduction ratio because the weak part is the teeth on the grears... with that much force you'll just break them right off! When you start looking for a press you need to think in terms of how large a coin you want to make. If you are satisfied with making coins the size of a dime or a penny, then a 30 to 40 ton press will be sufficient. But the force requirements go upward fast as the coins get larger. A quarter will need 75 tons, a half dollar needs 100 tons, and full silver dollar size coin requires at LEAST 150 tons. No matter what size press you get you will always wish you had got a larger one, but the smaller ones will still have various uses, such as punching blanks or making smaller coins. (I have eight presses now, six of which are working.) The most active coiner-craftsman community that I know of is involved with making coinage for the various SCA (Society for Creative Anachronism) groups around the country. They have moneyer's guilds and teach hand hammered medieval coining techniques. What part of the country are you in? Be well! Tom
I scanned a bit from 'coins and minting' by denis cooper: looks to me like the coin you posted was hammered like this: This was the main way to mint coins up until the 1500's Then you get into the manually operated machines: Here is a diagram of a screw press used by Benvenuto Cellini
Then you have the Rolling Mill as mentioned by Leonardo da Vinci. The obverse and reverse designs to be impressed on the coins were engraved on to the faces of rolls; the designs could either be rolled directly on to prepared blanks, or continously on to a strip, in the later case the coin would need to be cut from a strip like below the pictures show walzenwerke mill and an illustration of a taschenwerke mill:
Then by 1817 you have the Uhlhorns knuckle press that worked on a lever priniciple the mechanism carrying the upper die consisted of 3 links known as the 'sway lever' the 'column' and the 'hammer lever' and the die was fixed to the underside of the last. Both feed motion for the blanks and ejection motion for the struck coins. The operator had to run a flywheel up to sufficent speed and engage a clutch: Uhlhorns Knuckle Press Thonnelier's Knuckle Press Then there is the Boulton's steam engine driven automatic coining press. and then of course you have the sophisticated automated machines used today.
As for making the die...that is the hardest part. I have wanted to mint my own coins as well and the die (even with hammering, the most basic method besides casting) has proven to be the part I have been unable to do on a low budget do-it-yourself way. here is a pantograph reducing machine which copied and reduced in size a large model directly on to a steel die using a bronze cast of an artists plaster cast of an original work. The large original cast is mounted on the right, the die blank to be cut is mounted in the middle and the pivoting arrangement is on the left. The soft steel could be hardened after cutting and then used to strike removing the need to hand engrave dies and allowed for identical dies. They still use a somewhat similar way to make dies...using a larger original and reducing. I have yet to figure out how exactly is the best way to HAND engrave into something hard enough to strike coins with...have you ever tried to engrave on steel? or even get steel in the shape you need to hammer a coin? and make it look good enough to bother striking? I havent so far. Even softer metals are difficult, maybe I am just not using the right tools but I have yet to produce a die that isnt a disaster.
Making coin dies They key to making dies is a basic understanding of steel. Steel is an alloy of carbon with iron. At high temperature (like... red hot) the carbon dissolves into the iron and forms various different iron-carbides. But carbon is not stable in iron at normal temperatures! If the hot steel is quenched (cooled rapidly) the carbides are locked in place because the carbon has no time to come out of solution, and the steel is hard. But if it is cooled slowly, the carbon comes out of solution and forms granules in the iron matrix. That is referred to as "annealed" steel and it is very soft, nearly as soft as copper. It is extremely important to understand that the "condition" of any steel piece... whether and how it was heat-treated... is just as important as the alloy of the steel itself. The carbon content of the steel will determine the hardenability of the steel. Mild steel with carbon less than about 0.2% cannot be hardened. Various intermediate steels of 0.4% to 0.6% are sometimes used with mixed results. Good die steel will have carbon in the range of 0.9% up to a maximum of 1.5%. If you go higher than that you get into the range of cast irons which are very brittle. Adding other elements to the alloy generally slows the solubility of carbon and adds other properties. There are thousands of steel alloys known, and more being developed every day. Steel chemistry is EXTREMELY complex... but the basics are fairly simple... and that's enough to go on with. So for making dies you will purchase annealed tool steel stock. The cheapest is W-1 which is a water-hardening steel (that is, you quench from the austenitizing temperature of about 1550 degrees F into water to harden it). I generally use 2" diameter steel die-blanks 1.5" tall. After smoothing and preparing the top surface of the die, you can lay out your design and begin engraving. Gravers are like tiny wood-carving chisels specifically made for cutting soft steel and other metals. The tools and techniques of engraving are well elucidated in a number of books and videos. Any major jewelery supply firm, such as Rio Grande has a full line of tools. It is also possible to PUNCH into the soft steel instead of cutting it away by engraving. Punches are often used for lettering or small features such as stars. Larger punches called "puncheons" or "hubs" are used for entire thematic elements, such as faces or animals. And of course... you always have to remember to work backwards, since the coin is always a reverse mirror image of the die. After the die-sinking has been down, by whatever means (or combination of means) you have chosen, you then harden the die by heating it up and quenching it. There are heat-treating tables for every different steel alloy and they should be followed closely. After hardening... the die will (or should!) easily withstand the forces involved with striking designs in SOFT metals, such as copper, silver, gold etc. If you're careful, you can gently polish the flat die surface without impacting the design too much and achieve a near-proof effect. And here I should mention that the process of coining is NOT restricted to the making of coins per se! Metallurgically speaking, coining is any cold-forming process in which the metal FLOWS into recesses of the die under force. It is NOT the same as "stamping" in which the metal is bent and/or sheared, and which requires much smaller forces per unit area. Many items of modern manufacture besides coins and medals are coined... such as watch dials, key blanks, buttons, knobs, pocket-knife handles, gun parts, and face plates. So what that means is that there is a wealth of equipment out there that is perfectly suitable to coining that may not actually have ever been used in a mint. Screw presses and knuckle presses abound on the surplus equipment market. If you want to purchase one you'll have to start looking at what's around, and not get too excited and in a hurry. There are quite a few floating around so you can pick and choose. They are heavy, so having a good place to put it, and the ability to load and unload and move the things around is important. A solid grounding in basic metal-shop practice is essential... including lathe-work, milling, grinding, drilling, polishing, sawing, and filing, as well as the more specific tools and techniques associated with die-making. Good luck!
Yes ... Google search a guy named Daniel Carr and pattern coins. He designs and mints his own coins and submits them to Congress for consideration for future coin designs. Nice guy and I am sure that he could point you in the right direction.
Tom thanks for such a interesting talk on coin making that was facinating Drusus thanks for the pics again a great read and last but not least Josh good luck mate and dont forget to keep us informed of progress De Orc :kewl:
