Metal Casting Zone

I'm working on a project for a friend of mine who happens to own a brewery. We are working making a drink token - basically a wooden nickle; where you can purchase this token for the price of a beer or the bar tender can give you a free beer if you have one in process. We wanted something novel and something that would have some heft to it.

Anyway, I have the 'approved' design in the posted .PDF (note this is to scale), and the edge and text will be raised so the detail of this will be a little challenging. I have access to a 3D printer (buying one soon), and I can make high resolution models for the master. The attached photo shows a much earlier revision (and low res print).

The thickness of the token is 0.181" total, text and rim / edge is raised 0.08". I can add draft to the text when I print it, but releasing from the mold might still be an issue. I'm stuck with this font too - its part of the Tyranena marketing.

The metal we want to use is Copper because it should age well, and lead won't be an issue (plus I have over 160lb on hand).

Finally, the question:

I need to cast a few hundred of these. I was going to create an SLA master(s) that I could press into sand and simply pour the metal into the impression - but I have concerns about the detail between the text breaking. I could use my 90lb press to set the sand and make a jig to left it straight out of the sand (not smear or break the text details).

Lost wax would be labor intensive, but isn't out of the question.

I haven't found a plaster that will hold up yet - but I'm open to trying anything. I have a friend who is a potter, so I have access to gas fired kilns if I need too.

I have argon and CO2 gas shields that I can use to flood the molds which might help with the flux (I use Titanium tube in the top of my furnace and flood the crucible with CO2 or Argon to reduce the slag).


Making one of something is easy, but knocking out 250-400 is complicated.

Please let me know your thoughts.

Oh, I wondered why you made it backwards but then I noticed everything was backwards. The old self portrait in the mirror trick?

Sounds like a fun project, I think Greensnad isn't going to give you the details you want. You may need to use an oil based sand like Petro-bond. Lost wax would be the best but is very labor entensive. Having a kiln to use would help a lot. Copper is going to be tough, I've heard it doesn't cast well. Pewter would be the easiest, I've tried Brass twice and haven't got the mold burnt out enough yet. It spits metal back at you if it's not clean, and leaves a bunch of bubbles in the casting.
With Pewter, you may have a beers worth of pewter wrapped up in the token. then if people decide to collect or lose them, you are losing money. Leads cheap but it freaks people out, unless they are fishing.
Someone had an ivestment reciepe on here, I'm up to 50/50 Plaster of Paris and Silica flour. It seems to hold up well but I don't know about detail since I didn't burn it out enough. Looks Promising.
Keep us posted on your progress. Welcome to the forum!

Turns out “Raku” clay will hold the impression and can be low fired in a kiln. I’ve tried silica flour in the past, but the grit seems to inhibit the plasticity of the clay so it doesn’t hold detail from the stamped impression. I'm going to make a matrix of these, prob 5x5 and then pour the metal into it. The back of the coin will divot a bit in the back, so I will pour it a little thicker and then I can build a jig and post machine it on my milling machine.

The experiment I ran last night had mixed results with the copper – so I’m going to have to flood the mold with a gas shield of some sort. I won’t use a release agent since I’m going to make the mold sacrificial and beat it into submission to break the tokens out.

Thanks for ideas.

I’ll keep everyone posted how it turns out in the next few weeks.