Hi everyone,
As anyone has experience in casting metals that the melting point starts at 400/430º (806 F)?
What resin do you use for making the 3D printed part and what silicone do you use for it?
TIA
FG
I would use standard resin for the master part. All of the current colors are about the same but grey seems to have the most detail for me.
The silicone you use will depend a little on your process. Older tin cure silicones are very forgiving but have a bit of shrinkage after cure. Platinum cure silicones are more sensative to contaminates but don’t shrink. You’ll need to seal the printed part before casting the silicone mold for it to work. Obviously mold release for either type.
There are a ton of videos out there on how to make the molds etc. BJB enterprises, Alumalite, and Smooth On all have resources for mold makeing.
two answers
spin cast it. you need high temp silicone not black rubber.
http://www.romanoff.com/casting-machines/pewter/black-rubber-silicone-molds
http://www.cabemilano.com/index.php/en/item/gomme-siliconiche-a-180-c.html
or gravity pour in delf clay or green sand or petrobond
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Do NOT use tin cured silicones. They can not take that kind of heat without swelling dramatically. You want a high temperature tolerant platinum cure silicone- ask for it specifically. Even then, silicones will change dimension as they store heat- and they do not dissipate heat well… so you will be limited in how often you can cast the part.
To cast pot metal or pewter in large quantities and high quality you will want to use a vulcanized neoprene mold in a centrifugal casting machine. The reason you want to centrifuge the mold during casting is because all metals going from a molten to a solid state will Out Gas. In traditional Sand, investment, or ceramic shell casting, you are relying on the porosity of the mold material to allow the gasses to escape from the cavity…
But rubber molds will not allow gasses to escape- the purpose of a centrifuge is to drive the gasses toward the center of the mold and out the gate so that the part you are casting will not have gasses trapped in the cavity that will cause porosity in the casting.
Porosity is often hard to see with the naked eye- but in potmetal and pewter it often manifests as surfaces that will not take a bright polish, or that very rapidly darken after polishing. Under a microscope- the metal surface looks like a sponge.
For small parts you can also use a jewelers spring wound centrifuge with simple and inexpensive investment molds.
As to resin for the pattern… i do not know that you want to try and burn out a resin pattern at only 800 degrees… if you are printing the pattern to pull the silicone mold from- then you can print in any resin that gets the detail you want.
But if you are going to make spin casting molds in vulcanized neoprene… like the pros do, the resin has to be able to take the very high temperatures and pressures in a vulcanizing press. I would recommend the High Temp resin-
this is a pewter and white metal piece I did… the the copper and brass colors are actually areas that were selectively electroplated with copper, brass, or gold. and then some of the copper plated areas were also patinated with traditional bronze patina chemicals… a few small accents of enamel paint, too.
The exposed light colors are all raw pewter.
this is 15" tall- cast in about 13 parts… using 18" diameter vulcanized neoprene molds.
About as stiff as car tire rubber.
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PS-
this is what a white metal centrifugal casting machines look like- You can look for videos online that show them in action.
and this is what a neoprene mold looks like-
here is one being made- the metal figures are Patterns, being laid between two sheets of gum stock neoprene… the thing in the middle is a pattern for creating the central gate and metal distribution gating.
Another sheet of gumstock is laid on top, and the stack placed inside a steel ring in a vulcanizing press that heats the mold while squeezing it at around 3500 psi.
this is the finished vulcanized mold…
you can see that very thin ‘gates’ and ‘vents’ have been razor cut into one side of the mold to let the metal into the cavities and let the air out.
in the centrifuge a metal plate locks on top and squeezes the mold halves together, and molten metal is poured into the hole in the center, and flung by centrifugal force into the cavities. It spins fast enough to develop about 3-4 gs in the mold…
If you can’t afford a serious centrifuge- then you are better off using a Porous mold material like investment or sand so that the gasses can escape as the metal cools. that is, don’t try to cast metal in rubber molds at all.
Absolutely stunning piece @Sculptingman. Do you have a shop where items are for sale?
Chris
I did a whole raft of native american and wildlife sculptures about 25 years ago for a company called Legends.
We pioneered large scale white metal casting and lucite embedment- some of the pieces are 3 feet tall and 3 feet wide… cast in 50 separate parts soldered together and selectively electroplated.
They had a plating license and tanks for copper, nickle, black nickle, brass, and gold.- with pewter making a natural metallic white- I saw that as a whole palette of colors we could use to create visual dynamism while retaining the dramatic appearance of real metallic luster; so I pressed them to develop a means of masking parts of pewter castings for plating… we would first mask off everything we wanted to stay white… and plate copper- then mask off everything we wanted to stay copper and plate brass or gold.
The cool thing was we could then use standard bronze patinas on the copper areas because its the copper in bronze that the chemicals react with to produce other colors… and the plated surface being pure copper meant we got a much more saturated effect that was more stable.
You can find them all over the internet under the name C.A. Pardell
Thanks for sharing @Sculptingman. I love the coloring on this one
I didn’t see one of them I didn’t like!!!
Chris
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Thanks @Sculptingman
I search the internet but i didnt found a contact of the artist, or company?
Do you have a email ou site?
I only found pieces to sell from them…
The manufacturer is named Starlite Originals. They are in L.A-
but most of those pieces were limited editions that are only available on the resale market.
I don’t really have a site I would send anyone to- it was put up by someone who was not a designer… and most of what I do these days is done under NDA.