Foundry From Scrapped Oven for Cheap, Clean Castings

Home-built foundries are a popular project, and with good reason. Being able to melt and cast metal is a powerful tool, even if it’s “only” aluminum. But the standard fossil-fuel fired foundries that most people build are not without their problems, which is where this quick and clean single-use foundry comes into play.

The typical home foundry for aluminum is basically a refractory container of some kind that can take the heat of a forced-air charcoal or coal fire. But as [Turbo Conquering Mega Eagle] points out, such fuels can lead to carbon contamination of the molten aluminum and imperfections when the metal is cast. With a junked electric range, [Turbo Conquering Mega Eagle] fabricates a foundry that avoids the issue in an incredibly dangerous way. The oven’s heating element is wrapped around an old stainless saucepan, fiberglass bats from the stove insulate the ad hoc crucible, and the range’s power cord is attached directly to the heating element. The video below shows that it does indeed melt aluminum, which is used to sand cast a fairly intricate part.

We can’t see getting more than one use out of this setup, though, so it’s only as sustainable as the number of ranges you can round up. But it’s worth keeping in mind for one-off jobs. For a more permanent installation, check out this portable propane-powered foundry. And to see what you can make with one, check out this engine breather cast from beer cans.

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Portable Lightweight Foundry

[Makercise] is getting ready for Maker Faire. One of the things he’d really like to do is some casting demonstrations. However, he has no desire to take his expensive and heavy electric kiln based foundry to Maker Faire. So, he made his own.

He got into metal casting during his excellent work on his Gingery lathe series. He started off by modeling his plan in Fusion 360. He’d use a 16qt cook pot turned upside down as the body for his foundry. The top would be lined with ceramic fiber insulation and the lid made out of foundry cement. He uses a Reil style burner, which he also modeled as an exercise. This design is light and even better, allows him to lift the top of foundry off, leaving the crucible completely exposed for easy removal.

All went well with the first iteration. He moved the handles from the top to the bottom of the pot and filled it with insulation. He built legs for the lid and made a nice refractory cement bowl on the bottom. However, when he fired it up the bowl completely cracked along with his crucible. The bowl from design flaw, the crucible from age.

A bit put off, but determined to continue, he moved forward in a different direction. The ceramic insulation was doing so well for the top of the foundry that he decided to get rid of the cement altogether and line the bottom with it as well. The lid, however, would be pretty bad for this, so he purchased another pot and cut the top portion of it off, giving him a steel bowl that matched the top.

The foundry fires up and has worked well through multiple pours. He made some interesting objects to hopefully sell at Makerfaire and to test the demonstrations he has planned. The final foundry weighs in at a mere 15lbs not including the fuel cylinder, which is pretty dang light. Video after the break.

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From Shop Floor Dust To Carbon Steel

[Chandler Dickinson] did his monthly sweep of the floor in his blacksmith’s shop when it occurred to him that all that metal dust had to go somewhere, didn’t it? So he did the only reasonable thing and made a crude foundry out of cinder blocks, melted his dirt in it, and examined what came out the other end.

His first step was to “pan” for steel. He rinsed all the dirt in a bucket of water and then ran a magnet at the bottom of the bucket. The material that stuck to the magnet, was ripe for reclaimation.

Next he spent a few hours charging a cinderblock foundry with coal and his iron dust. The cinderblocks cracked from the heat, but at the end he had a few very ugly brittle rocks that stuck to a magnet.

Of course there’s a solution to this non-homogenous steel. As every culture with crappy steel eventually discovered, you can get really good steel if you just fold it over and over again.  So he spend some time hammering one of his ugly rocks and folding it a bit. He didn’t get to two hundred folds, but it was enough to show that the resulting slag was indeed usable iron.

He did a deeper examination of the steel last week, going as far as to etch it, after discovering that the metal sparked completely differently when sanded on one side versus the other. It definitely needed work, but all seemed to have worked in the end.

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The Best Gingery Lathe Video Series To Date

[Makercise] has been working on a Gingery Lathe since September last year. His videos on the process are by far the most detailed, clearly shot, and complete series on making a Gingery lathe we’ve come across.

For those who aren’t familiar, the Gingery series of books describe how to build an entire machine shop’s worth of bench top tools using only the hardware store, dumpster dives, charcoal, and simple skills. The series of books start out with the charcoal foundry. [Makercise] has built a nice oil fired foundry already so it’s off to the next book, Gingery 2,  is the metal lathe.

The Gingery books and, really, most DIY books from that era are: not well laid out, well written, or even complete. All but the most recent prints of the series still looked like photocopies of typewritten documents with photos glued on. The series provided just enough detail, drawings, and advice to allow the hobbyist to fill in the rest. So it’s really nice to see someone work through the methods described in the book visually. Seeing someone using a scraper made from an old file on aluminum to true the surface is much more useful than Gingery’s paragraph or two dedicated to the subject.

[Makercise] is fast approaching the end of his lathe build. We’re not certain if he’ll move onto the Shaper, mill, drill press, brake, etc. after finishing the lathe, but we’re hopeful. The playlist is viewable after the break.

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Custom Engine Parts from a Backyard Foundry

Building a car engine can be a labor of love. Making everything perfect in terms of both performance and appearance is part engineering and part artistry. Setting your creation apart from the crowd is important, and what better way to make it your own than by casting your own parts from old beer cans?

[kingkongslie] has been collecting parts for a dune buggy build, apparently using the classic VW Beetle platform as a starting point. The air-cooled engine of a Bug likes to breathe, so [kingkongslie] decided to sand-cast a custom crankcase breather from aluminum.

Casting solid parts is a neat trick but hardly new; we’ve covered the techniques for casting plastic, pewter, and even soap. The complexity of this project comes from the fact that the part needs to be hollow. [kingkongslie] managed this with a core made of play sand and sodium silicate from radiator stop-leak solution hardened with a shot of carbon dioxide. Sure, it looks like a Rice Krispie treat, but a core like that will stand up to the molten aluminum while becoming weak enough to easily remove later. The whole complex mold was assembled, beer cans melted in an impromptu charcoal and hair-dryer foundry, and after one false start, a shiny new custom part emerged from the sand.

We’ve got to hand it to [kingkongslie] – this was a nice piece of work that resulted in a great looking part. But what we love about this is not only all the cool casting techniques that were demonstrated but also the minimalist approach to everything. We can all do stuff like this, and we probably should.

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The First 5nm Chip

For almost forty years, integrated circuits have become smaller and smaller. These chips started out with massive transistors in the early 1970s. They shrank to less than 1μm by 1990, and shrank yet again to less than 100nm by the turn of the last century. Now, Imec and Cadence are experimenting with 5nm technology – the smallest technology available for any mass-produced integrated circuit.

The history of microelectronic fabrication over the last decade is a story of failure. Something happened in 2005, and although chips could be designed at ever-smaller technologies, the transition to these smaller manufacturing processes didn’t go as smoothly as in the 70s, 80s, and 90s. Just a few years ago, Intel said 10nm chips would ship by 2015. These chips are nowhere to be found, and even 14nm technology is still catching up to the yields found in 22nm technology. In 2009, Nvidia said their flagship graphics card would be built with a 11nm process. The current Nvidia flagship desktop graphics card is built with 28nm technology. Moore’s law isn’t 18 months anymore.

While Imec and Cadence have completed the tapeout on a 5nm device, it’s just a test chip. Before starting manufacturing on a single process node, Intel and others will tapeout a simple test chip to verify their latest process. This 5nm tapeout will not become a manufactured chip, but it does mean we’ll see more talk about the 5nm process in the future.

Kentucky-Fried Induction Furnace

[John] and [Matthew] built an induction-heater based furnace and used it to make tasty molten aluminum cupcakes in the kitchen. Why induction heating? Because it’s energy efficient and doesn’t make smoke like a fuel-based furnace. Why melt aluminum in the kitchen? We’re guessing they did it just because they could. And of course a video, below the break, documents their first pour.

Now don’t be mislead by the partly low-tech approach being taken here. Despite being cast in a large KFC bucket, the mini-foundry is well put together, and the writeup of exactly how it was built is appreciated. The DIY induction heater is also serious business, and it’s being monitored for temperature and airflow across the case’s heatsinks. This is a darn good thing, because the combination of high voltage and high heat demands a bit of respect.

Anyway, we spent quite a while digging through [John]’s website. There’s a lot of good information to be had if you’re interested in induction heaters. Nonetheless, we’ll be doing our metal casting in the back yard.

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