3D Printed Forge For Recycling

If you own a CNC and have kept tabs on metal prices these past few years (honestly months), you might shed a small tear as you watch chips fly off your work and into the trash. With a sigh, these flecks and pieces are consigned to be the cost of machining a part. Thankfully, the fine folks at [ActionBox] have been working on a 3d printed plaster forge for recycling their metal scraps.

The team ordered some graphite crucibles of a few sizes from a large online bookstore and started 3D printing some molds for crucible holders. They started with a smaller version to try the method. While the walls were too thin in that initial version, the approach was proven. With slightly thicker walls, the medium-sized version worked much better. The goal of the forge was to smelt copper as they had a lot of thick copper wire lying around. Armed with several propane torches, they started melting aluminum and brass, which worked reasonably well. However, the melting point of copper continued to elude them (1984°F or 1085°C).  To counter this, the [ActionBox] team bought some new torches that provided significantly higher BTU output, while still fitting the holes in the mold. This did the trick!

The mold to accommodate the large crucible was massive and printed in four sections. The team did melt copper successfully and had four ingots to show off. We want to stress how dangerous molten copper and other metals are, particularly regarding things you might not realize have moisture soaked up inside. Proper PPE is essential to use these things without getting hurt. [ActionBox] has some helpful pointers in that area, but they admit they are relatively new to forging and casting themselves. Perhaps version two can incorporate a flip lid for added safety.

Video after the break.

30 thoughts on “3D Printed Forge For Recycling

    1. I got as far as the part where he added water to plaster, and then when it came out lumpy he declared this was because he was using the wrong tool (and asked the youtube comments(!) for tips). At that point I sensed I hadn’t found my guru.

      1. One guru that you could check out is myfordboy, https://www.youtube.com/c/myfordboy/videos. He has published over 100 “metal casting at home” videos (mainly aluminum) along with sand mould making. Typically the things he casts is pieces to be used for making his own machines/motors/miniature steam engine/etc from scratch.

        I guess the bubbles in the aluminum bar from this video was caused by hydrogen. This is a known problem when melting aluminum, with a known solution which myfordboy explains (and makes a dedicated degassing tool).

  1. The implications of performing this amateur operation outside, in an uncontrolled environment, on a high rise balcony, no less, are just….
    I don’t even have words.
    irresponsible doesn’t even begin to describe my feelings about this. Litigation aside, the considerations of safety to the other tenants is a complete afterthought.
    His warnings about safety are ludicrous.
    I don’t want to be that guy, but this takes the cake.

    1. As opposed to doing it indoors?

      Yeah, I’m with you about melting metal on an apartment balcony. Not cool! Although, at least they only seem to have used the tiny crucible there. I’m not sure that little bit of aluminum would have made it all the way through the floor to the downstairs neighbor. Assuming of course they put the resulting fire out quickly. Copper and brass though… man that stuff is nasty when melted. It needs to be respected!

      It looks like they went down to ground level for the larger one. But they are still right up against the wall of the building. Why do something like this up against the building? They are not ready to be doing this.

      I think this should be done in a back yard, away from everything. Preferably of a private residence where you don’t have other apartment residents just wandering by. And only when the weather forecast and a look up at the sky both agree there is no rain coming.

      But you seem to be suggesting indoors. Well.. maybe in the middle of a dirt-floored metal barn with all the doors open for ventilation. I get the impression if you told these guys to take it inside they would take it to the busy parking structure.

      1. Indoors isn’t all that problematic on the small scale anyway, a little provision for fume extraction, some protective surfaces and fire extinguisher and the job is done (not really much different to welding and soldering indoors at the tiny scale they are trying), but I agree I wouldn’t want to see this lot try it, they would find some way to make it horrifying…

        1. A concrete floor likely has some moisture in it. I’ve seen videos of tiny pieces of it popping off when metal was accidentally spilled both messing up the floor and sending little splashes of molten metal up towards the pourer’s skin.

          Thus my mention of a dirt-floored barn.

          1. Indeed, hence my mention of protective surfaces – something suitable, which at small scale can just be a sheet of pretty cheap steel, though concrete is almost certainly fine too – the volume of a full on spill with such tiny crucible is so low as to be less than the little spatter from a bigger operation, probably not even enough to heat concrete fast and hot enough to create large enough steam explosions to be noticed, if it can even create one at all.

            (of course just how wet and how much mass and heat your spill has really matters here, but small scale metal casting, particularly of lower temp alloys like white metal are easy to do safely indoors with some care, and its not impossible to go somewhat larger/hotter safely either – outdoors is undoubtedly easier to set up safely though).

            And of course you also have to assume proper PPE that makes the inevitable little spatter/spill almost safe…

    2. My former neighbor was watching forged in fire back in 2017. He decided to try out forging himself with a barrel in his back yard on a day with 40mph winds. Burnt down 4 houses and damaged 21. Did over $4 million in damage on the street include $80k to my house.

      Yeah, shouldn’t be doing this on your balcony.

  2. OK. maybe 50 bucks worth of crucibles and molds, 100 bucks worth of propane torches which the idiots melted, fifteen bucks worth of gas and some scrap. net results, eight bucks worth of porous ingots which are not especially useful for anything. I’m quite impressed but not in a good way. Gloves? I’m not handling crucibles of molten metal without proper gloves. Other safety issues too numerous to mention. I expect that the words “Hey, watch this” will be on their headstones.

  3. Wow all the love for this video makes me want to watch it, even though I had no intention of doing so…

    All I wanted was to see a picture of the foundry mold – looking for the reason to not just modify a beer keg like almost everyone else that doesn’t just buy a foundry…

    1. Wow that was painful to watch even at fast forward speeds, not sure a single thing they did made any sense at all, and at such a pathetically tiny scale why would you not use an electric foundry design – much harder to screw up with really…

  4. Agreed.

    For anyone reading and would like to do this, try mixing vermiculite in with the plaster instead of sand. It adds insulation so less heat escapes. Also, use the “without gravel” version of concrete for a smoother surface.

    Add powdered chalk (calcium carbonate) to the molten aluminum before the pour to remove dissolved gases (which will be bubbles in the ingot). Wrap some in a folded piece of aluminum foil and press to the bottom of the crucible with a rod.

    Heat your molds before pouring to drive off any water.

    1. Plaster of Paris is pretty happy to calcinate back to powder if it’s at high temperature for a while. I built my furnace out of fire clay and sand, and it’s done really well, hundreds of heats at yellow-hot, but these days you can buy DAP brand castable refractory intended for repairing or building fireplaces. It’s really neat: it pours as nicely as his plaster.

  5. OMG.

    How many close calls does this guy need before he realizes that he’s one bad pour from serious burns or dropping molten metal through his balcony? This is a great How NOT To video.

    His rationale for doing this is bs anyway. Small scale smelting into dubious quality metal is never going to be more profitable than selling your chips to the recyclers and buying known metal. If you cut dry then they should be considered clean chips and have more value. Make sure you don’t mix metals.

  6. Certainly not their worst safety issue but since I don’t see anyone else mentioning this one… maybe a respirator for the brass melting? Then again I suppose “discovering” and documenting metal flu could be material for another video. Everyone has to make a living doing something, right?

  7. May I suggest that the writer learn the difference between a “forge” and a “foundry”? I *only* looked at this because of the idiot title to see if anyone else pointed out the gaffe.

    Hint: This is *not* a forge.

      1. Not to Be nit picky but since you felt the need to correct him.
        A foundry is a building or structure that houses all the metallurgy equipment.

        Hint: This is not a foundry either
        its simply a “Melting Furnace”

    1. May I suggest that the commenter learn the difference between a “foundry” and a “Melting Furnace”? I *only* looked at this because of the idiot comment to see if anyone else pointed out the hypocrisy

      Hint: This is *not* a “Foundry”.

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