Casting Metal Directly Into 3D Printed Molds

Casting metal and 3D printing go together like nuts and gum, and there are no shortage techniques that use the two together. Lost PLA casting is common, and sculptors are getting turned on to creating their works in plastic first before sending it off to the foundry. Now the folks at FormLabs have turned the whole ‘casting metal and 3D printer’ thing on its head: they’re printing sacrificial molds to cast pewter.

There are two techniques demonstrated in this tutorial, but the real winner here is printing a complete sacrificial mold for pewter miniatures. While this technique requires a little bit of work including washing, curing, and a bit of post-processing, you would have to do that anyway with anything coming out of a resin printer.

The material of choice for these molds is a high temp resin with a heat deflection temperature of 289 °C. Using a pewter alloy that melts at 260 °C, casting a metal miniature is as simple as pouring molten metal into a mold. Demolding might be a little finicky, but with a small screwdriver used as a chisel, it’s possible to get the cast newly parts out.

We’ve seen pewter casting with PLA, but the quality available from the Form resin printers is truly amazing and produces some great looking miniatures.

24 thoughts on “Casting Metal Directly Into 3D Printed Molds

      1. no need for VPN, I figured it out. clicking the link takes me to the site, which triggers their localization redirect and I end up at…, which does not exist. if I then manually change the url to…. I get the desired content.

  1. A slightly safer alternate is BiInSnZn which melts at a very similar temperature and is substantially less toxic: lead alloys can be if handled. Fine for general use though, the low melting point makes recycling a lot easier
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  2. That’s pretty respectable. High Temp has an HDT of 289 °C @ 0.45 MPa—the highest on the 3D printing materials market.

    It even beats out Carbon3D’s CE 221.

    “With a 231°C heat deflection temperature, strength, and stiffness, CE 221 is perfect for applications that need long term thermal stability, like under-the-hood components, electronics assemblies, and industrial products.”

    1. FDM is the dream but metal usually goes from solid to liquid skipping the gooey stage thermoplastics have. It can be done I am sure but it is much more difficult, too bad we can’t easily run 50/50 solder as feedstock in a reprap.

    2. one would think so but in common practice it sometimes isnt, metal sintering powders usually arent just metal powder, casting on the other hand is fairly “easy”, it is an involved process and there is a lot that can go wrong but it isnt complicated as such.

      with a good master and a couple of working copies it is fairly easy to scale production, it really is only a matter of work, mould and metal to make more, in essence it is almost as cumbersome to make a single casting as it is to make 20, the mould making is really the only extra work.

    3. Technically, yes. However, metal 3d printing is still an expensive process and involves things that are not consumer friendly (very expensive powdered metals, operator protection equipment, the machines themselves, vacuum chambers, lasers, metal melting ovens, etc). Plus, the resolution tends to be more limited. Prints are also much more expensive and also tend to require post finishing as well.

      That will change, eventually. There is some neat upcoming technology that is trying to do so but nothing that I am aware of on the low end.

    1. Because most solvents do not really impact the UV resin. You also cannot really burn out the molding as the temperature differential between them is not high enough really either. You would melt the metal being cast.

      1. Not even Methyl Ethyl Ketone or Dichloromethane? They are not listed on the material spec sheet, which to the cynic is seen as meaningful. That most can’t touch it is not as important as if any one solvent can. Repeated cycles of soaking, freezing and then desiccating may also fracture the resin and speed up the solvent attack too.

        1. You can try a few different ones. The major issue is going to be the volume of what you are trying to do. Are you trying to dissolve the entire photopolymer or just remove some residue? Dissolving bulk cured photopolymer is not something I understand to be straightforward and not something I have explored at length either but it can depend on the underlying chemistry. Some UV photopolymers are urethane based, which are more likely to be attacked by some of the “common” solvents. Others are epoxy based and there are several other major chemistries as well.

          Here’s a review of a wide variety of solvents.

          A better approach would be that many of them embrittle when cool, you could try that as the metal is not really likely to break when cold. Maybe some kind of vibratory process to automate things? That’s already done in industry.

  3. Does anyone have any opinions on whether the SparkMaker team can deliver? Their kickstarter has about two weeks left and they have way way more orders than their threshold. The price is good though, if it’s not vapourware.

    1. Cheap SLA printers appear to be what cheap FDM printers were a few years back. They pop up all over the place and have mass production prices combined with almost fully experimental hardware and shortcuts.

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