Fail Of The Week: Bronze-Brazed Wrought Iron

September 4, 2022 by Jonathan Bennett 16 Comments

[Will Stelter], a promising young blacksmith working out of Montana, had a terrific idea for a unique composite material for finishing off a knife build. This build is a collaboration between multiple blacksmiths, and as the youngster of the group, [Will] really wanted to pull out the stops and finally make a material he’d been contemplating for years to impress the elders. He knows that if you try to forge wrought iron at too low a temperature, it develops cracks and splits. Could you do this on purpose, and then fill these cracks with bronze? It would be quite the stunning material, with the bright bronze veins running through the dark iron. He had to try.

Unfortunately, our young experimenter ran into some problems that didn’t have enough time to overcome. First, getting the bronze to flow and fill the voids of the iron was a challenge, particularly when heating with a torch. Throwing the whole experiment into a forge resulted in the bronze leaking through the enclosure. The most promising attempt was a beefed-up box, set in an oven for about 20 minutes, with the temperature high enough to liquefy the bronze. It was looking great, until he cut into it and found too many air pockets for a workable billet.

The attempt was a failure, but we’re delighted that [Will] went ahead and put the video out there anyway. And if you know how to make this work, go drop a comment on his channel, and we’ll all look forward to a part two, where he finally nails the technique.
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Casting A Cannon Is A Lot Harder Than You Think

June 2, 2019 by Brian Benchoff 23 Comments

We’ve seen backyard casting, and for the most part, we know what’s going on. You make a frame out of plywood or two by fours, get some sand, pack it down, and very carefully make a mold around a pattern. This is something else entirely. [FarmCraft101] is casting a bronze cannon. Sure, it’s scaled down a bit, but this is the very limit of what sanity would dictate a single person can cast out of molten metal.

This attempt at casting a cannon is more or less what you would expect from a backyard bronze casting experiment. There’s a wooden flask and a greensand mold, everything is tamped down well and there’s a liberal coating of talcum powder inside. This is a large casting, though, and this presented a problem: during the pour, the halves of the flask were only held together with a few c-clamps. This ended poorly, with molten bronze pushing against the mold and eventually flowing onto the garage floor. Doing this alone was perhaps a bad idea.

The failure of the mold meant some math was necessary, and after some quick calculations it was found that more than 300 pounds pushing the sides of the mold apart. A second pour, with the sides of the flask bound together with nylon straps, was much more successful with a good looking bronze cannon ready for some abuse with a wire wheel.

This is only the first video in the series, with the next videos covering the machining and boring out of the barrel. That’s some serious craft right there.

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Lost PLA Casting Brings Out The Beauty Of Macromolecules

January 2, 2017 by Dan Maloney 6 Comments

Biochemistry texts are loaded with images of the proteins, nucleic acids, and other biopolymers that make up life. Depictions of the 3D structure of macromolecules based on crystallography and models of their most favorable thermodynamic conformations are important tools. And some are just plain beautiful, which is why artist [Mike Tyka] has taken to using lost-PLA casting to create sculptures of macromolecules from bronze, copper, and glass.

We normally don’t cover strictly artistic projects here at Hackaday, although we do make exceptions, such as when the art makes a commentary on technology’s place in society. In [Mike]’s case, not only is his art beautiful and dripping with nerd street cred, but his techniques can be translated to other less artsy projects.

For “Tears”, his sculpture of the enzyme lysozyme shown in the banner image, [Mike] started with crystallographic data that pinpoints every peptide residue in the protein. A model is created for the 3D printer, with careful attention paid to how the finished print can be split apart to allow casting. Clear PLA filament is used for the positive because it burns out of the mold better than colored plastic. The prints are solvent smoothed, sprues and air vents added, and the positive is coated with a plaster mix appropriate for the sculpture medium before the plastic is melted out and the mold is ready for casting.

[Mike]’s sculpture page is well worth a look even if you have no interest in macromolecules or casting techniques. And if you ever think you’ll want to start lost-PLA casting, be sure to look over his build logs for plenty of tips and tricks. “Tears” is executed in bronze and glass, and [Mike]’s description is full of advice on how to handle casting such vastly different media.

Thanks to [Dave Z.] for the tip.

Metal Casting With Single Shelled PLA Masters

July 20, 2016 by Gerrit Coetzee 21 Comments

[3DTOPO] does a lot of metal casting (video link, embedded below). That’s obvious by the full and appropriate set of safety gear, a rarity on YouTube.

They had all the equipment to do it the normal way: craft or CNC out a master, produce a drag and a copy, make any necessary cores, and finally; pour the mold. This is a long and tedious process. It has a high rate of error, and there is a parting line.

Another set of methods are the lost ones. With these methods the master is produced out of a material like foam or wax. The master is surrounded by refractory and then melted, burned, or baked out of the mold. Finally the metal is poured in. Theoretically, a perfect reproduction is made without ever having to open the mold.
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A quick brush over the part with some sand paper and it quickly transforms from obviously plastic to metallic.

Learn Resin Casting Techniques: Cold Casting

July 14, 2016 by Gerrit Coetzee 36 Comments

Sometimes we need the look, feel, and weight of a metal part in a project, but not the metal itself. Maybe you’re going for that retro look. Maybe you’re restoring an old radio and you have one brass piece but not another. It’s possible to get a very metal like part without all of the expense and heat required in casting or the long hours in the metal fabrication shop.

Before investing in the materials for cold casting, it’s best to have practical expectations. A cold cast part will not take a high polish very well, but for brushed and satin it can be nearly indistinguishable from a cast part. The cold cast part will have a metal weight to it, but it clinks like ceramic. It will feel cool and transfers heat fairly well, but I don’t have numbers for you. Parts made with brass, copper, and iron dust will patina accordingly. If you want them to hold a bright shine they will need to be treated with shellac or an equivalent coating afterward; luckily the thermoset resins are usually pretty inert so any coating used on metal for the same purpose will do.

It is best to think of the material as behaving more or less like a glass filled nylon such as the kind used for the casing of a power tool. It will be stiff. It will flex a relatively short distance before crazing and then cracking at the stress points. It will be significantly stronger than a 3D printed part, weaker than a pure resin part, and depending on the metal; weaker than the metal it is meant to imitate.

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Bronze Casting With MakerBot

October 5, 2010 by Jakob Griffith 16 Comments

That, dear readers, is the smell of a new Hackspace opening up in Davenport Iowa. It is also the lovely scent of burning plastic. Because how do you celebrate a new Hackerspace? By casting bronze coins of course!

Begin by having a MakerBot extrude plastic coins, then compact the plastic coin in sand to produce a mold. Heat up your bronze in a trashcan furnace and pour it into the mold. The plastic melts away and you’re left with a bronze coin.

There are probably some safety measures and precautions that should be followed as well…