Repurposed Plastic Protects PCBs

An errant wire snipping across the wrong electrical pins spells the release of your magic smoke. Even if you are lucky, stray parts are the root of boundless malfunctions from disruptive to deadly. [TheRainHarvester] shares his trick for covering an Arduino Nano with some scrap plastic most of us have sitting in the recycling bin. The video is also after the break. He calls this potting, but we would argue it is a custom-made cover.

The hack is to cut a bit of plastic from food container lids, often HDPE or plastic #2. Trim a piece of it a tad larger than your unprotected board, and find a way to hold it in place so you can blast it with a heat gun. When we try this at one of our Hackaday remote labs and apply a dab of hot glue between the board and some green plastic it works well. The video suggests a metal jig which would be logical when making more than one. YouTube commenter and tip submitter [Keith o] suggests a vacuum former for a tighter fit, and we wouldn’t mind seeing custom window cutouts for access to critical board segments such as DIP switches or trimmers.

We understand why shorted wires are a problem, especially when you daisy-chain three power supplies as happened in one of [TheRainHarvester]’s previous videos.

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Growing Your Own Insulation

The latest craze in revolutionary materials science is no longer some carbon nanotube, a new mysterious alloy, or biodegradeable plastic. It seems as though a lot of new developments are coming out of the biology world, specifically from mycologists who study fungi. While the jury’s still out on whether or not it’s possible to use fungi to build a decent Star Trek series, researchers have in fact been able to use certain kinds of it to build high-performing insulation.

The insulation is made of the part of the fungus called the mycelium, rather than its more familiar-looking fruiting body. The mycelium is a strand-like structure of fungus which grows through materials in order to digest them. This could be mulch, fruit, logs, straw, crude oil, or even live insects, and you might have noticed it because it’s often white and fuzzy-looking. The particular type of mycelium used here is extremely resistant to changes in temperature so is ideal for making insulation. As a bonus, it can be grown, not manufactured, and can use biological waste products as a growing medium. Further, it can grow to fit the space it’s given, and it is much less environmentally harmful than existing forms of insulation.

As far as performance is concerned, a reporter from the BBC tested it in an interesting video involving a frozen chocolate bar and a blowtorch, discovering also that the insulation is relatively flame-retardant. Besides insulation, though, there are many more atypical uses of fungi that have been discovered recently including pest control and ethanol creation. They can also be used to create self-healing concrete.

Thanks to [Michael] for the tip!

Photo of fungal mycelium: Tobi Kellner [CC BY-SA 3.0]

To Ferrule Or Not To Ferrule?

We recently posted about a spectacular 3D-printer fire that was thankfully caught and extinguished before spreading to the hacker’s house or injuring his family. Analyzing the remains of the printer, the hacker determined that the fire was caused when a loose grub screw let the extruder’s heater cartridge fall out and touch the ABS fan shroud. It ran full-on and set things on fire.

A number of us have similar 3D printers, so the comments for this article were understandably lively, but one comment stood out by listing a number of best practices for wiring, including the use of ferrules. In particular, many 3D printers connect the heated bed, which draws a lot of current, with screw terminals to the motherboard. While not the cause of the fire in the original post, melted terminal blocks are a common complaint with many DIY 3D printer kits, and one reason is that simply jamming thick stranded wire into a screw terminal and hoping for the best can result in increased resistance, and heat, at the joint. In such situations, the absolutely right thing to do is to crimp on a ferrule. So let’s talk about that.

 

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Kapton: Miracle Material With A Tragic History

On a balmy September evening in 1998, Swissair flight 111 was in big trouble. A fire in the cockpit ceiling had at first blinded the pilots with smoke, leaving them to rely on instruments to divert the plane, en route from New York to Geneva, to an emergency landing at Halifax Airport in the Canadian province of Nova Scotia. But the fire raging above and behind the pilots, intense enough to melt the aluminum of the flight deck, consumed wiring harness after wiring harness, cutting power to vital flight control systems. With no way to control the plane, the MD-11 hit the Atlantic ocean about six miles off the coast. All 229 souls were lost.

It would take months to recover and identify the victims. The 350-g crash broke the plane into two million pieces which would not reveal their secrets until much later. But eventually, the problem was traced to a cascade of failures caused by faulty wiring in the new in-flight entertainment system that spread into the cockpit and doomed the plane. A contributor to these failures was the type of insulation used on the plane’s wiring, blamed by some as the root cause of the issue: the space-age polymer Kapton.

No matter where we are, we’re surrounded by electrical wiring. Bundles of wires course with information and power, and the thing that protects us is the thin skin of insulation over the conductor. We trust these insulators, and in general our faith is rewarded. But like any other engineered system, failure is always an option. At the time, Kapton was still a relatively new wonder polymer, with an unfortunate Achilles’ heel that can turn the insulator into a conductor, and at least in the case of flight 111, set a fire that would bring a plane down out of the sky.

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DIY Cryogel Sustains Live Cells

We like to think our readers are on the cutting edge. With the advent of CRISPR kits at home and DIY bio blooming in workshops across the world, we wanted to share a video which may be ahead of its time. [The Thought Emporium] has just shown us a way to store eukaryotic cells at room temperature. His technique is based on a paper published in Nature which he links to from the YouTube page, but you can see his video after the break.

Eukaryotic cells, the kind we are made of, have been transported at low temperatures with techniques like active refrigeration, liquid nitrogen, and dry ice but those come with a host of problems like cost, convenience, and portability. Storing the cells with cryogel has been shown to reliably keep the cells stable for up to a week at a time and [The Thought Emporium] made some in his homemade freeze-dryer which he’s shown us before. The result looks like a potato chip, but is probably less nutrious than astronaut ice cream.

If cell transport doesn’t tickle your fancy, cryogel is fascinating by itself as a durable, lightweight insulator similar to Aerogel. You can make Aerogel at home too.
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Fool Giants With Novelty-Sized Gold Bricks

If you ever wondered how to make a giant-sized gold bar out of sheets of pink household insulation, well, there is a video showing you the steps. YouTube workshop guru [Jimmy DiResta] built oversized prop gold bricks out of foam. He cut sheets of 1.5″ Owens Corning foam insulation on his Saw Stop, making angled edges onto each piece so they could fit together in the trapezoidal ingot shape we know and love.

The pieces were put together with Great Stuff insulating foam sealant, the sort of spray foam used for filling up gaps in your house’s insulation, but here serving as glue.  [Jimmy] created lettering by lasering out the shapes in what appears to be cardboard, then gluing the letters in place, using the leftover material from the laser cut to place the letters in neat rows. He then sanded down the edges, priming and painting the bars with gold paint–but there were too many imperfections visible so he re-sanded and repainted.

We have been inundated in foam projects recently, like this ultralight built out of foam insulation and a foam cutter built with a 9V battery.

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3D Printer Enclosure Is Pleasant On The Eyes And Ears

There’s a lot going on in the 3D printing world. Huge printing beds, unique materials like concrete, and more accessible, inexpensive printers for us regular folk. The only thing that’s often overlooked with these smaller printers is the ruckus that they can make. The sounds of all those motors can get tiresome after a while, which was likely the inspiration for [Fabien]’s home 3D printer workstation. (Google Translate from French)
After acquiring a new printer, [Fabien] needed a place to put it and created his own piece of furniture for it. The stand is made out of spruce and is lined with insulation. He uses a combination of cork, foam, and recycled rubber tile to help with heat, sound, and vibration respectively. Don’t worry, though, he did install a ventilation system for the fumes! After the printer housing is squared away, he place a webcam inside so that the user can monitor the print without disturbing it. Everything, including the current print, is managed with a computer on the top of the cabinet.
Having a good workspace is just as important as having a quality tool, and [Fabien] has certainly accomplished that for his new 3D printer. There have been a lot of good workspace builds over the years, too, including electronics labs in a portable box and this masterpiece workbench. If you’ve ever experienced the frustration of working in an area that wasn’t designed for the task at hand, you’ll easily be able to appreciate any of these custom solutions.