Weed Eater String Made From Plastic Bottles

For those who don’t mind constantly adding tiny but measurable amounts of microplastics to their landscaping, string trimmers are an excellent way of maintaining edging around garden beds, trimming weeds, or maintaining ground covers on a steep hill. One problem with them, though, is that not only is the string consumable but it can be expensive. Plus, if you have a trimmer with a proprietary spool you need to hope the company never goes out of business. Or, you can simply refill your string spool with this handy tool.

The build uses plastic bottles to create the string from what would likely become garbage anyway. First, a sharp roller-style knife slices the plastic into a long thin strip. Once cut, it is fed through a heater similar to a hot end on a 3D printer which allows the plastic to be deformed or forged into a cylinder. From there the plastic is added onto a spool, which also has the motor in it that drives the entire mechanism. In this case it is using an old variable-speed drill.

From the comments on the video, there is some discussion about the economics of using this string in a weed eater. It’s likely the plastic won’t last as long as specialty string trimmer string, and the time and expense of making the plastic may never save much money. But we have to give credit to the ingenuity nonetheless. And, if you’re really into recycling plastic just for the sake of keeping it out of the landfill, there are plenty of other ways to go about accomplishing that goal.

I will NEVER buy weed whip line again! from landscaping

Ceramic stove (credit: Felix Reimann)

Same Taste With Less Energy: Optimizing The Way We Cook Food

Preparing food is the fourth most energy-intensive activity in a household. While there has been a lot of effort on the first three — space heating, water heating, and electrical appliances — most houses still use stoves and ovens that are not too dissimilar to those from half a century ago.

More recent technologies that make cooking more efficient and pleasant have been developed, such as induction heating. Other well-known and common appliances are secretly power savers: microwaves and electric kettles. In addition, pressure cookers enable the shortening of cooking times, and for those who like dishes that take hours to simmer, vacuum-insulated pans can be a real energy-saver.

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Sea Level Rise From Melting Ice Sheets Could Soon Be Locked In

Where today we talk broadly of climate change and it’s various effects, the conversation was once simpler. We called it “global warming” and fretted about cooking outside in the summer and the sea level rise that would claim so many of our favorite cities.

Scientists are now concerned that sea level rises could be locked in, as ice sheets and glaciers pass “tipping points” beyond which their loss cannot be stopped. Research is ongoing to determine how best we can avoid these points of no return.

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Machine Learning Does Its Civic Duty By Spotting Roadside Litter

If there’s one thing that never seems to suffer from supply chain problems, it’s litter. It’s everywhere, easy to spot and — you’d think — pick up. Sadly, most of us seem to treat litter as somebody else’s problem, but with something like this machine vision litter mapper, you can at least be part of the solution.

For the civic-minded [Nathaniel Felleke], the litter problem in his native San Diego was getting to be too much. He reasoned that a map of where the trash is located could help municipal crews with cleanup, so he set about building a system to search for trash automatically. Using Edge Impulse and a collection of roadside images captured from a variety of sources, he built a model for recognizing trash. To find the garbage, a webcam with a car window mount captures images while driving, and a Raspberry Pi 4 runs the model and looks for garbage. When roadside litter is found, the Pi uses a Blues Wireless Notecard to send the GPS location of the rubbish to a cloud database via its cellular modem.

Cruising around the streets of San Diego, [Nathaniel]’s system builds up a database of garbage hotspots. From there, it’s pretty straightforward to pull the data and overlay it on Google Maps to create a heatmap of where the garbage lies. The video below shows his system in action.

Yes, driving around a personal vehicle specifically to spot litter is just adding more waste to the mix, but you’d imagine putting something like this on municipal vehicles that are already driving around cities anyway. Either way, we picked up some neat tips, especially those wireless IoT cards. We’ve seen them used before, but [Nathaniel]’s project gives us a path forward on some ideas we’ve had kicking around for a while.

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Throw Out That Box? No, Build A Shelving Unit

Are you one of those people who hoards cardboard for someday, and then periodically breaks it all down and puts it out for recycling because you haven’t done anything with it yet? Well, load up a new blade in the utility knife and fire up that hot glue gun, because the [Cardboard Ninja]’s gonna show you how to make a shelving unit from the biggest box in your collection.

[Cardboard Ninja] goes about the build quite smartly, cutting the legs from the four long bends already in the cardboard. This is repeated in the shelves, which are made from the box’s sides — [Cardboard Ninja] takes advantage of the bends when it comes to cutting out the shelves and creates the other three with the edge of a metal ruler. The rest of the cardboard is devoted to supports for shelves and legs.

While you could use this unit to hold all the other, smaller boxen you have lying around, that would be a gross under-utilization. You see, the way this is put together, it can hold upwards of 133 lbs (60 kg) total, provided the rules of weight distribution are followed, and the heaviest things are on the bottom shelf.

That does seem like a lot of weight, but given that this was constructed by someone who has a holster for their utility knife and calls themselves [Cardboard Ninja], I think we can trust their stress tests and just go with it. Given that, it’s always a good idea to anchor shelving units to the wall.

You know, this would make a pretty good entry into the second Challenge of this year’s Hackaday Prize. Remember: this is the final weekend to enter, and the window closes at 7AM Pacific on Sunday, so get hackin’!

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Revolving Doors Aren’t Just Annoying, They’re Energy Saving Too

While most of us have been content with swing and sliding doors for the vast majority of our needs around the home, the revolving door remains popular in a wide variety of contexts.

It’s a confounding contraption that always feels ready to snatch and ensnare the unwary user. However, these doors do have certain benefits that have allowed them to retain popularity in many public buildings around the world. Let’s dive in to why below.

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How To Make A Difference Through Plant Metabolism

Generally when we consider the many plants around us, we imagine them efficiently using the electromagnetic radiation from the Sun via photosynthesis in their leaves — pulling carbon-dioxide from the air, as well as water from the soil via their roots, and grow as quickly as they reasonably can. In reality, the efficiency of this process is less than 10% of the input energy, and the different types of plant metabolisms that have formed over the course of evolution aren’t all the same.

Among the plant metabolisms in use today, some use significantly more efficient carbon fixation pathways, while others end up wasting a lot of the energy they obtained from photosynthesis with unnecessarily complicated processes, especially to deal with waste. How fast plants can grow if they had all evolved the most efficient carbon fixation pathway has been the subject of a number of studies these past decades, involving everything from crop plants to trees.

As these studies are showing us, more than a scientific and evolutionary biological curiosity, these genetically engineered plants offer real opportunities in everything from food production to reforestation.

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