# How to cast a gold coin



## Metaphore (Oct 25, 2015)

I want to make a coin as a gift for a friend's wedding. The couple on 1 side and some writing on the other.

Is there a a description of a process or a tutorial on how to do this? If not, I'd be happy to take some advice and document the process as I do it.

Thanks!
m


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## Smack (Oct 26, 2015)

There has been a post or 2 about it, try a search.


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## NobleMetalWorks (Oct 26, 2015)

If you want to cast anything in precious metals, your best bet would be to do lost wax/investment casting.

However, their is several pieces of equipment as well as materials you would need to accomplish this.

Here are a few links about lost wax casting:

http://www.instructables.com/id/Lost-Wax-Casting/

http://www.ganoksin.com/borisat/directory/library/subject/33

I would suggest that you either have the casting done by a company that will custom cast what you intend to replicate or have made, or find a community college or artistic group such as a maker space, etc, take the class or classes required and do it in class using their equipment and consumable supplies. You can easily learn how to cast in one semester.

There is another easier option for making a coin that does not involve casting, you can use precious metal clay or PMC by it's retail name. This is a metal clay that uses organic binders. Because the binders are organic, once fired the organics are burned off and you are left with a pure metal result. PMC can be purchased in several different alloys. It does shrink a bit after you design what it is you are intending to make, but this might be an easier option to accomplish what it is you are attempting.

You might choose a company such as this to do the casting for your design:

http://www.milwaukeeprec.com/lost-wax-casting.html

You might even find a art group, or again a makers space or otherwise where you can learn how to shape the clay, and then use their equipment to fire it. Here are some links on precious metal clay:

http://www.riogrande.com/category/metal-clay,-glass,-enamels-and-resins/Metal-Clay

https://www.etsy.com/market/precious_metal_clay

I actually make precious metal clay myself, but I'm not ready to market anything yet as I'm still working out ways of preventing shrinkage. I wouldn't attempt making the clay yourself but instead purchase what you need from Rio Grande in the provided link above or from some other reputable retailer. I believe Rio Grande still purchases metal clay scrap, so you can also sell your excess clay back to them.

Hope this helps.

Scott


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## rickbb (Oct 26, 2015)

The lost wax method is the best quality casting, but does require some investment in tooling and a learning curve. Lost wax is what custom jewelry and art objects are made with.

Sand casting is the next in line quality wise, less tooling to buy/make and slightly quicker learning curve. You have to buy sand made for the purpose, can't use regular sand.


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## Metaphore (Oct 26, 2015)

NobleMetalWorks said:


> If you want to cast anything in precious metals, your best bet would be to do lost wax/investment casting.
> Scott



Scott, thanks for the links and explanation. Looks like doing this would be more of a project than I thought it would be. I was hoping there was a simple way to take a 3D printed coin and make a mold for a gold one.



rickbb said:


> The lost wax method is the best quality casting, but does require some investment in tooling and a learning curve. Lost wax is what custom jewelry and art objects are made with.
> 
> Sand casting is the next in line quality wise, less tooling to buy/make and slightly quicker learning curve. You have to buy sand made for the purpose, can't use regular sand.



Thanks! I'll check it out.


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## upcyclist (Oct 27, 2015)

Metaphore said:


> NobleMetalWorks said:
> 
> 
> > If you want to cast anything in precious metals, your best bet would be to do lost wax/investment casting.
> ...



There is in fact a way of doing just that--make a mold of your 3D-printed coin, then inject that mold with wax, and use the wax pattern for the traditional lost-wax casting process. Personally, I use centrifugal casting, but do the investment and mold-making with a vacuum table. There are a number of companies that will do that for you, or a hobbyist like me could do it as well. Up to you. A given company may or may not be willing to cast in the exact gold alloy you want, so shop around. Some will only do 14K yellow or white, some will do rose, 18K, 24K, etc.

Shapeways[.com] is actually a 3D design and printing service, but they print in wax and cast in Sterling or gold. An upside of shapeways is that you can just send them the CAD file, and you can even list the CAD file in their design catalog and get paid a royalty if others use it as well. Note that these guys charge by the cubic centimeter for gold work, and it'll be done to mass-production standards. With a small jeweler/smith, you'll get handmade/heirloom quality, but be prepared to pay for that increased quality.

--Eric


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## justinhcase (Oct 27, 2015)

A nice coin is struck not cast.
i have been toying with the Idea of getting myself a die made.
I quite like the idea of being able to pay off people in Gold Just's.


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## Metaphore (Oct 27, 2015)

justinhcase said:


> A nice coin is struck not cast.
> i have been toying with the Idea of getting myself a die made.
> I quite like the idea of being able to pay off people in Gold Just's.



Sounds intriguing. How much force is needed to mint gold or silver?

Have you gotten any price quotes for a die?


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## justinhcase (Oct 27, 2015)

Metaphore said:


> justinhcase said:
> 
> 
> > A nice coin is struck not cast.
> ...


About £150 for a so so etching,about £450 for a really nice job.
The smaller and finer the detail in you design the more they will charge to make it,got to pay a good artist a good wage.
Most large city's with a good tool manufacturing industry will have some one who can make one.
Now a day's they use hydraulic ram's,The old day's it was a man with a sledge hammer .
The nasty job was the chap who held the die in place as he would get hit once in a while.
The purer your alloy the easier it is to form.
I hammer small button's into a nice even rectangle's with just a small ball-pain.
http://www.ebay.co.uk/itm/Tool-Die-Steel-Forming-Hobs-Jewelry-Coining-Stamping-Die-Block-Manufacturing-/331677296937?


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## upcyclist (Oct 27, 2015)

justinhcase said:


> A nice coin is struck not cast.



Agreed--if having a die made is a reasonable expense, they're the way to go. Generally this is for when you're producing large quantities. 

For a one-off, unless you're making a 1 troy ounce gold coin and don't mind if it costs and extra 10-20% to have the die made, you might want to stick to casting. My opinion.


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## Metaphore (Oct 27, 2015)

What about laser engraving? Is that doable for a gold coin?


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## Grelko (Oct 27, 2015)

Metaphore said:


> What about laser engraving? Is that doable for a gold coin?



You could always get a tattoo artist etc, since they're "usually" very good with pictures/drawings and use a dremel or engraving tool for it. You'd need a magnifying glass held in place over the coin and a blown up picture of the couple, but it would work. I'm not sure on the cost though. Some jewelry shops can do engraving also.


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## justinhcase (Oct 28, 2015)

If a tattoo artist wanted to get into engraving he could,Not sure how you are meant to chisels delicate work off of hardened steel,very skilled craftsmanship.
Laser would work the Sheffield assay office use one for hallmark now,but having run several four and five watt unit's for the entertainment industry in the 90's.the high speed step motors used in the axis control are a bit sensitive and prone to problem's when you are projecting a pattern half a mile away and fifty foot high.
The control you would need to etch metal and the power you would have to control safely would be exponentially more difficult a very expensive bit of kit.
I believe you can acid etch a deep enough relief to get a design to transferable but they tend to be quite shallow due to the technique.
An ole garage press or jack that can push five tun's and a die is the cheapest way to crank them out.
You could just cast them in cuttlefish shell by pushing a coin in hard.that was the first method ever used.
https://www.youtube.com/watch?v=cK47_0QK-fw
I have since seen you can get an laser engraver for less than £60,is it not fantastic how fast we develop.
http://www.gearbest.com/3d-printers-3d-printer-kits/pp_240242.html?currency=GBP&gclid=CjwKEAiAo7C2BRDgqODGq5r38DsSJAAv7dTP-z2T0BxvbWRN_4MGPjjRZUl2EiINUvaVoqdfsoqjSRoCY1Tw_wcB


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## youngling (Feb 23, 2016)

I am a small time refiner based out of india, we do make coins for local establishments here - the designs are outdated and i'd like to overhaul our whole coining dept. I am a novice and clueless where to start, i realise getting things in order will take a good long time - i am prepared for that.
I have access to tool rooms in the country , with the latest 3D laser engraving machine and such. i would like to personally oversee designing and engraving of the die,and i have no clue about where to start, what software to learn ?

I'd be immensely grateful if someone could help me out and point me in the right direction. Thank you!


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## upcyclist (Feb 24, 2016)

Youngling, check out shapeways.com. Even if you don't end up using their services to have your final dies made, they have a pretty good intro to 3-D printing and milling. Their "how-to" info includes which applications to use, and they're pretty standard.


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## nickvc (Feb 24, 2016)

I have always been fascinated by the minor art treasures that some coins can be, I have owned coins from Alexander the Great to the Roman Empire and early english stamped and milled coins but I find many modern coins rather flat.
To be honest to create something more than a flat photographic image with a slightly raised profile is hard and needs the skills of a good engraver, many ancient images are almost caricatures of the real person but no less beautiful for that and the reverses can be just as stunning.
If all you want is an image of your friends get a gold disc, you can buy them off the shelf, and get someone to laser engrave it with a photo of them, in my opinion not a work of art but a great way to show you care 8)


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