Kill the Exhaust, Not Your Lungs with the Fume Coffin

As if slinging around 40 watts of potentially tattoo-removing or retina-singeing laser beams wasn’t anxiety-inducing enough, now comes a new, scary acronym – LCAGs, or “laser-generated airborne contaminants.” With something that scary floating around your shop, it might be a good idea to build a souped-up laser cutter exhaust fan to save your lungs.

We jest, but taking care of yourself is the responsible way to have a long and fruitful hacking career, and while [patternmusic]’s “Fume Coffin” might seem like overkill, can you go too far to protect your lungs? Plywood and acrylic, the most common materials that come across a laser cutter’s bed, both release quite a witch’s brew of toxins when vaporized by a laser beam. The Fume Coffin clears the air in your shop by venting it to the outdoors after giving it a good scrubbing through an activated charcoal pre-filter and a HEPA polishing element. Both filters are commercially available so replacements won’t be an issue, and the entire thing is housed in a wooden box that gives the device its name.

Since it’s ejecting 200 cubic feet per minute, you’ll have to provide at least that much make-up air, but other than that the Fume Coffin should be a welcome addition to the shop. We’ve seen a few other attempts to handle LCAGs effectively before, including a DIY charcoal and automotive air filter design.

Solar Bulldozer Gets Dirty

As the threat of climate change looms, more and more industries are starting to electrify rather than using traditional fuel sources like gasoline and diesel. It almost all cases, the efficiency gains turn out to be environmentally and economically beneficial. Obviously we have seen more electric cars on the roads, but this trend extends far beyond automobiles to things like lawn equipment, bicycles, boats, and even airplanes. The latest in this trend of electrified machines comes to us from YouTube user [J Mantzel] who has built his own solar-powered bulldozer.

The fact that this bulldozer is completely solar-powered is only the tip of the iceberg, however. The even more impressive part is that this bulldozer was built completely from scratch. The solar panel on the roof charges a set of batteries that drive the motors, and even though the bulldozer is slow it’s incredibly strong for its small size. It’s also possible for it to operate on solar alone if it’s sunny enough, which almost eliminates the need for the batteries entirely. It’s also built out of stainless steel and aluminum, which makes it mostly rust-proof.

This is an impressive build that goes along well with [J Mantzel]’s other projects, most of which center around an off-grid lifestyle. If that’s up your alley, there is a lot of inspiration to be had from his various projects. Be sure to check out the video of his bulldozer below as well. You don’t have to build an off-grid bulldozer to get started in the world of living off-the-grid, though, and it’s easy to start small with just one solar panel and a truck.

Thanks to [Darko] for the tip!

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Robot Lives in Your Garden and Eats the Weeds

You can’t deny the appeal of gardening. Whether it’s a productive patch of vegetables or a flower bed to delight the senses, the effort put into gardening is amply rewarded. Nobody seems to like the weeding, though — well, almost nobody; I find it quite relaxing. But if you’re not willing to get down and dirty with the weeds, you might consider deploying a weed-eating garden robot to do the job for you.

Dubbed the Tertill, and still very much a prototype, the garden robot is the brainchild of some former iRobot employees. That’s a pretty solid pedigree, and you can see the Roomba-esque navigation scheme in action — when it bumps into something it turns away, eventually covering the whole garden. Weed discrimination is dead simple: short plants bad, tall plants good. Seedlings are protected by a collar until they’re big enough not to get zapped by the solar-powered robot’s line trimmer.

It’s a pretty good idea, but the devil will be in the details. Will it be able to tend the understory of gardens where weeds tend to gather as the plants get taller? Can it handle steep-sided raised beds or deeply mulched gardens? Perhaps there are lessons to be learned from this Australian weed-bot.

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Hackaday Prize Entry: Collaborative Water Purification

Look over any description of a water treatment plant, and you’ll find a description that includes the words, ‘coagulation tanks’. What are these treatment plants coagulating? You don’t want to know. How are they doing it? With chemicals and minerals. Obviously, there’s something else that can be done.

For their Hackaday Prize entry, [Ryan], [designbybeck], [Clint], [Wanda] and [Maker Mark] are investigating electrocoagulation. It’s an alternative to a frothy brew of chemicals that uses electricity to pull pollutants out of the water.

Right now, the tests are much smaller in scale than the tens of thousands of gallons you’d find at a water treatment plant. In fact, the test rig is only a 16-ounce mason jar. While this isn’t large enough to precipitate pollutants out of a household water supply, it is big enough for a proof of concept.

The team is using two electrodes for this build, one aluminum, and one iron. These electrodes are connected via alligator leads to the electronics board they’ve built. This electronics board is basically just an H-Bridge (used so they can reverse the polarity of the field emitter and prevent a buildup of gunk on the electrodes) and a few connectors to a power supply. The results are encouraging; they have a few time-lapse videos of a mason jar of dirty water clearing up with the power of electricity. It’s a great project with some great documentation. The team already has a bunch of updates on their project and instructions on how to replicate their hardware. You can check out those videos below.

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Build Your Own Hydroponic Wheel

Hydroponics is an effective way of growing plants indoors through the use of water medium and artificial lighting. It often involves having a system to raise and lower the water level around the plants to let the roots breathe, however this can require some non-trivial plumbing. [Peter] wanted to instead explore the realm of wheel hydroponics to grow some ingredients for salad.

The idea is to have pods mounted on a rotating assembly, similar to the carriages on a Ferris Wheel. By rotating the wheel slowly, each pod spends a certain amount of time submerged, and a certain amount of time in free air. This allows the water level to remain constant and only the pods need to move.

The tank for the build is a simple plastic storage bin from a local hardware store, with the wheel assembled from various odds and ends and laser cut components, making this a build very possible for those with access to a hackerspace. A stepper motor provides the motive power, with the assembly completing approximately one rotation per hour.

[Peter] has run the device for several months now, noting that there are issues with certain plants maintaining their hold to the wheel, as well as algae growth in the water medium. There’s room for development but overall, it’s a great build and we hope [Peter] will be serving up some delicious fresh salads soon.

For another take, perhaps you’d like your hydroponics solar powered?

[Thanks Nils!]

To Deal with Plastic Trash, All You Need is Bugs

Outlawed now in some places, or only available to tote your purchases at a ridiculous premium, the billions of “T-shirt” bags used every year present a serious waste management problem. Whether blowing across the landscape like synthetic tumbleweeds, floating in the ocean as ersatz jellyfish, or clogging up municipal waste streams, finding a way to deal with them could really make a difference. And finding a bug that eats polyethylene and poops antifreeze might be a great first step in bioremediating the mess.

As with many scientific discoveries, learning about the useful and unexpected eating habits of the larval stage of the Greater Wax Moth Galleria mellonella can be chalked up to serendipity. It began when biochemist [Federica Bertocchini] cleaned a wax moth infestation from her beehive. She put the beeswax-loving pests in a plastic bag, later finding they had chewed their way out. Intrigued, she and [Paolo Bombelli] ran some experiments using the bugs. They showed the mechanism wasn’t just mechanical and that the worms were digesting the polyethylene, to the tune of 92 mg consumed for 100 worms in 12 hours. That’s about 1,000 times faster than bioremediation with bacteria.

Furthermore, the bugs excrete ethylene glycol, a useful industrial chemical, in the process. Finally, to see if the process can scale, the researchers showed that a homogenate of wax moth larvae could digest PE sheets. This could lead to an industrial process if the enzymes involved can be isolated and engineered. The letter describing the process is a fascinating read.

While this one may not a classically hackish way to deal with plastic recycling, the potential for this method is huge. We look forward to seeing where this goes.

[Images: César Hernández/CSIC]

A Cool Mist that Dries Your Clothes

This one is both wild enough to be confused as a conspiracy theory and common sense enough to be the big solution staring us in the face which nobody realized. Until now. Oak Ridge National Laboratory and General Electric (GE), working on a grant from the US Department of Energy (DOE), have been playing around with new clothes dryer technology since 2014 and have come with something new and exciting. Clothes dryers that use ultrasonic traducers to remove moisture from garments instead of using heat.

If you’ve ever seen a cool mist humidifier you’ll know how this works. A piezo element generates ultrasonic waves that atomize water and humidify the air. This is exactly the same except the water is stored in clothing, rather than a reservoir. Once it’s atomized it can be removed with traditional air movement.

This is a totally obvious application of the simple and inexpensive technology — when the garment is laying flat on a bed of transducers. This can be implemented in a press drying system where a garment is laid flat on a bed or transducers and another bed hinges down from above. Poof, your shirt is dry in a few seconds.

But individual households don’t have these kinds of dryers. They have what are called drum dryers that spin the clothes. Reading closely, this piece of the puzzle is still to come:

They play [sic] to scale-up the technoloogy to press drying and eventually a clothes dryer drum in the next five months.

We look at this as having a similar technological hurdle as wireless electricity. There must be an inverse-square law on the effect of the ultrasonic waves to atomize water as the water moves further away from the transducers. It that’s the case, tranducers on the circumference of a drum would be inefficient at drying the clothing toward the center. This slide deck hints that that problem is being addressed. It talks about only running the transducers when the fabric is physically coupled with the elements. It’s an interesting application and we hope that it could work in conjunction with traditional drying methods to boost energy savings, even if this doesn’t pan out as a total replacement.

With a vast population, cost adds up fast. There are roughly 125 M households in the United States and the overwhelming majority of them use clothes dryers (while many other parts of the world have a higher percentage who hang-dry their clothing). The DOE estimates $9 billion a year is spent on drying clothes in the US. Reducing that number by even 1/10th of 1% will pay off more than tenfold the $880,000 research budget that went into this. Of course, you have to outfit those households with new equipment which will take at least 8-12 years through natural attrition, even if ultrasonics hit the market as soon as possible.

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