Microwave Forge Casts The Sinking-est Benchy Ever

September 15, 2024 by Dan Maloney 7 Comments

As a test artifact, 3DBenchy does a pretty good job of making sure your 3D printer is up to scratch. As an exemplar of naval architecture, though — well, let’s just say that if it weren’t for the trapped air in the infilled areas, most Benchy prints wouldn’t float at all. About the only way to make Benchy less seaworthy would be to make it out of cast iron. Challenge accepted.

We’ve grown accustomed to seeing [Denny] over at “Shake the Future” on YouTube using his microwave-powered kilns to cast all sorts of metal, but this time he puts his skill and experience to melting iron. For those not in the know, he uses standard consumer-grade microwave ovens to heat kilns made from ceramic fiber and lots of Kapton tape, which hold silicon carbide crucibles that get really, really hot under the RF onslaught. It works surprisingly well, especially considering he does it all on an apartment balcony.

For this casting job, he printed a Benchy model from PLA and made a casting mold from finely ground silicon carbide blasting medium mixed with a little sodium silicate, or water glass. His raw material was a busted-up barbell weight, which melted remarkably well in the kiln. The first pour appeared to go well, but the metal didn’t quite make it all the way to the tip of Benchy’s funnel. Round two was a little more exciting, with a cracked crucible and spilled molten metal. The third time was a charm, though, with a nice pour and complete mold filling thanks to the vibrations of a reciprocating saw.

After a little fettling and a saltwater bath to achieve the appropriate patina, [Denny] built a neat little Benchy tableau using microwave-melted blue glass as a stand-in for water. It highlights the versatility of his method, which really seems like a game-changer for anyone who wants to get into home forging without the overhead of a proper propane or oil-fired furnace. Continue reading “Microwave Forge Casts The Sinking-est Benchy Ever” →

The Thermite Process Iron Foundry

July 5, 2024 by Jenny List 13 Comments

The thermite process is a handy way to generate molten iron in the field. It’s the reaction between aluminium metal and iron oxide, which results in aluminium oxide and metallic iron. It’s hot enough that the iron is produced as a liquid, which means it’s most notably used for in-field welding of things such as railway tracks. All this is grist to [Cody’s Lab]’s mill of course, so in the video below the break he attempts to use a thermite reaction in a rough-and-ready foundry, to make a cast-iron frying pan.

Most of the video deals with the construction of the reaction vessel and the mold, for which he makes his own sodium silicate and cures it with carbon dioxide. The thermite mix itself comes from aluminium foil and black iron oxide sand, plus some crushed up drinks cans for good measure.

The result is pretty successful at making a respectable quantity of iron, and his pour goes well enough to make a recognizable frying pan. It has a few bubbles and a slight leak, but it’s good enough to cook an egg. We’re sure his next try will be better. Meanwhile this may produce a purer result, but it’s by no means the only way to produce molten iron on a small scale.

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Retrotechtacular: The Power To Stop

April 23, 2022 by Dan Maloney 22 Comments

In everyday life, the largest moving object most people are likely to encounter is probably a train. Watching a train rolling along a track, it’s hard not to be impressed with the vast amount of power needed to put what might be a mile-long string of hopper cars carrying megatons of freight into motion.

But it’s the other side of that coin — the engineering needed to keep that train under control and eventually get it to stop — that’s the subject of this gem from British Transport Films on “The Power to Stop.” On the face of it, stopping a train isn’t exactly high-technology; the technique of pressing cast-iron brake shoes against the wheels was largely unchanged in the 100 years prior to the making of this 1979 film. The interesting thing here is the discovery that the metallurgy of the iron used for brakes has a huge impact on braking efficiency and safety. And given that British Railways was going through about 3.5 million brake shoes a year at the time, anything that could make them last even a little longer could result in significant savings.

It was the safety of railway brakes, though, that led to research into how they can be improved. Noting that cast iron is brittle, prone to rapid wear, and liable to create showers of dangerous sparks, the research arm of British Railways undertook a study of the phosphorus content of the cast iron, to find the best mix for the job. They turned to an impressively energetic brake dynamometer for their tests, where it turned out that increasing the amount of the trace element greatly reduced wear and sparking while reducing braking times.

Although we’re all for safety, we have to admit that some of the rooster-tails of sparks thrown off by the low-phosphorus shoes were pretty spectacular. Still, it’s interesting to see just how much thought and effort went into optimizing something so seemingly simple. Think about that the next time you watch a train go by.

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Retrotechtacular: The Art Of The Foundry

November 27, 2019 by Dan Maloney 19 Comments

Mention the term “heavy industry” and the first thing to come to mind might well be the metal foundry. With immense machines and cauldrons of molten metal being shuttled about by crane and rail, the image of the foundry is like a scene from Dante’s Inferno, with fumes filling a vast impersonal factory, and sparks flying through the air. It looks like a dangerous place, as much to the soul as to the body, as workers file in each day to suffer mindlessly at the hearths and ladles, consumed in dirty, exhausting work even as it consumes them.

Things are not always as they appear, of course. While there’s no doubting the risks associated with working in a foundry such as the sprawling Renfrew works of Babcock and Wilcox Ltd. in the middle of the previous century, as the video below shows the work there was anything but mindless, and the products churned out by the millions from this factory and places like it throughout the world were critical to today’s technology.

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A No-Cost, Heavy Metal Lathe From Junkyard Parts

March 8, 2019 by Dan Maloney 28 Comments

We have to admit that our first thought on seeing a Frankenlathe made from old engine blocks was that it was a set piece from a movie like The Road Warrior. And when you think about it, the ability to cobble together such a machine tool would probably make you pretty handy to have around in an apocalypse.

Sadly, surviving the zombie mutant biker uprising seemed not to be the incentive for [Paul Kuphaldt]’s version of the [Pat Delany] “Multimachine”. He seemed to be in it for the money, or more precisely from the lack of it. He was shooting for a zero-dollar build, and although he doesn’t state how close he came, we’re going to guess it was pretty close. The trick is to find big castings for the bed and headstock – Mopar slant 6 blocks in this case. The blocks are already precision machined dead flat and square, and the cylinder bores provide ample opportunities for stitching the castings together. The drivetrain comes from a 3-speed manual transmission, a 3/4-ton Chevy truck axle donated the spindle, and a V8 cylinder head was used for the cross slide. The tailstock seems to be the only non-automotive part on the machine.

We’d love to see a video of it in action, but there are ample pictures on [Paul]’s website to suggest that the heavy castings really make a difference in keeping vibration down. Don’t get us wrong – we love cast aluminum Gingery lathes too. But there’s something substantial about this build that makes us feel like a trip to the boneyard.

[via r/homemadetools]

Move Over Aluminum: Cast Iron For The Home Foundry

June 15, 2018 by Dan Maloney 53 Comments

When it comes to choice of metals that can be melted in the home foundry, it’s a little like [Henry Ford]’s famous quip: you can melt any metal you want, as long as it’s aluminum. Not that there’s anything wrong with that; there’s a lot you can accomplish by casting aluminum. But imagine what you could accomplish by recycling cast iron instead.

It looks like [luckygen1001] knows a thing or two about slinging hot metal around. The video below shows a fairly expansive shop and some pretty unique tools he uses to recycle cast iron; we were especially impressed with the rig he uses to handle the glowing crucibles from a respectful distance. The cast iron comes from a cheap and abundant source: car disc brake rotors. Usually available free for the asking at the local brake shop, he scores them with an angle grinder and busts them into manageable chunks with a hammer before committing them to the flames. The furnace itself is quite a thing, running on a mixture of diesel and waste motor oil and sounding for all the world like a jet engine starting up. [luckygen1001] had to play with the melt, adding lumps of ferrosilicon alloy to get a cast iron with better machining properties than the original rotors. It’s an interesting lesson in metallurgy, as well as a graphic example of how not to make a flask for molding cast iron.

Cast iron from the home shop opens up a lot of possibilities. A homemade cast aluminum lathe is one thing, but one with cast iron parts would be even better. And if you use a lot of brake rotors for your homebrew cast iron lathe, it might require special handling.

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Iron Casting In The Parking Lot

April 28, 2012 by Mike Szczys 3 Comments

Here’s one good thing about the bitter cold Midwestern winter, it helps keep you from overheating when working around a hot furnace. Back in February this iron pour happened in the parking lot of the Madison, Wisconsin based Sector67 Hackerspace. Look, they’re making iron hearts!

Now this isn’t just a bunch of members who got together and decided to do some casting. As you can tell in the video after the break the team knows what they’re doing. The event was a collaboration with FeLion Studios, a custom cast-iron art boutique. But the Hackerspace participants did get to take part in the process of building the cast, watching the pour, and cleaning up the rough results.

One of the people from FeLion Studios just appeared on the Martha Stuart Show, along with a 550 pound cast-iron frying pan United States map. [Chris] from Sector67 tells us the New York frying pan that [Martha] is hold was a product of the parking lot pour.

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