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

Protect Your Tomatoes With A 9V Battery

Growing fresh vegetables at home is a popular pastime, even moreso in a year when we’ve all been locked inside. However pests can easily spoil a harvest, potentially putting a lot of hard work down the drain. [Matt] of [DIY Perks] isn’t one to give up his tomatoes without a fight, however, and came up with a solution to protect his plants.

The trick is to take advantage of the mildly conductive slime excreted by snails as they travel along the ground. To protect potted plants, [Matt] places two strips of copper tape around the perimeter of the pot, spaced about a centimeter apart. Each strip is connected to one terminal of a 9 V battery. When a snail attempts to cross the strips, it completes a circuit between the two, and the electrical current that flows irritates the snail, forcing it to retreat.

[Matt] notes that no snails were harmed in the making of the video, and that the solution is far kinder to the slimy critters than poisons or traps. He also goes so far as to demonstrate alternative solutions for garden beds, as well. We’ve more commonly seen [Matt] working with lighting, though it’s great to see he has a bit of a green thumb, too. Video after the break.

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Tend Your Garden… Again

In the early 1940s, several countries saw an incredible shift in agriculture. What were called “victory gardens” were being planted en masse by people from all walks of life, encouraged by various national governments around the world. Millions of these small home gardens sprang up to help reduce the price of produce during World War 2, allowing anyone with even the tiniest pot of soil to contribute to the war effort.

It’s estimated that in 1943 alone, victory gardens accounted for around one third of all vegetables produced in the United States. Since then, however, the vast majority of these productive gardens have been abandoned in favor of highly manicured, fertilized, irrigated turfgrass (which produces no food yet costs more to maintain), but thanks to the recent global pandemic there has been a resurgence of people who at least are curious about growing their own food again, if not already actively planting gardens. In the modern age, even though a lot of the folk knowledge has been lost since the ’40s, planting a garden of any size is easier than ever especially with the amount of technology available to help.

As someone who not only puts food on the table as a writer for a world-renowned tech website but also literally and figuratively puts food on the table as a small-scale market farmer, there are a few things that I’ve learned that I hope will help if you’re starting your first garden.

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Herb Garden Is Smarter Than The Average… Garden

After 13 days, the herbs are showing good signs of growth.

Herbs are a great way to spice up any dish. Often they don’t need much, meaning that it’s possible to grow a useful amount in a fairly compact area. [Sunyecz22] wanted to do just that, so built a convenient indoor herb garden, giving it some smarts along the way.

The project is built around an Arduino Mega, a venerable stalwart of the scene that comes in handy on projects requiring plenty of digital I/O. It’s paired with four soil moisture sensors, one per planter pot to keep an eye on water levels. The system also controls LEDs which provide light based on the time of day to help the herbs grow. Finally, a tidy 3D printed enclosure gives the project a neat, finished look.

It’s a build that’s a straightforward way to get into automatic plant maintenance, and leaves plenty of scope for future work. With the capable Arduino Mega on hand, it would be a cinch to upgrade to automatic watering down the track. We’ve seen similar builds before, too. Video after the break.

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Building A Geodesic Dome Greenhouse

Greenhouses are a great way to improve conditions for your plants, and are an absolute necessity for any serious gardening in colder climates. When the time came for [gentleworks] to build a new greenhouse, rather than going with a conventional design, they decided to go with a geodesic dome instead.

The greenhouse uses a few techniques that will be unfamiliar to those used to run-of-the-mill carpentry. The individual cedar struts meet at a series of hubs, constructed out of short lengths of Schedule 80 PVC pipe. The struts are attached to the pipe with steel straps, screwed into place. This doesn’t give the strongest of holds, but as most of the loads on the struts are compressive in nature, it works well in practice. Plastic sheeting is used as a covering to help let in plenty of light while keeping the cold out. The greenhouse is also heated, and can maintain a 40 deg F temperature differential with 14,000 BTUs.

It’s a build that has us wanting to throw up a dome or two in our own backyard. We’ve seen other geodesic structures before; if you’re working on one yourself, be sure to drop us a line.

Give Your Solar Garden Lights A Color Changing LED Upgrade

White LEDs were the technological breakthrough that changed the world of lighting, now they are everywhere. There’s no better sign of their cost-effective ubiquity than the dollar store solar garden light: a complete unit integrating a white LED with its solar cell and battery storage. Not content with boring white lights on the ground, [Emily] decided to switch up their colors with a mix of single-color LEDs and dynamic color-changing LEDs, then hung them up high as colorful solar ornaments.

The heart of these solar devices is a YX8018 chip (or one of its competitors.) While the sun is shining, solar power is directed to charge up the battery. Once the solar cell stops producing power, presumably because the sun has gone down, the chip starts acting as a boost converter (“Joule thief”) pushing a single cell battery voltage up high enough to drive its white LED. Changing that LED over to a single color LED is pretty straightforward, but a color changing LED adds a bit of challenge. The boost converter deliver power in pulses that are too fast for human eyes to pick up but the time between power pulses is long enough to cause a color-changing circuit to reset itself and never get beyond its boot-up color.

The hack to keep a color-changing LED’s cycle going is to add a capacitor to retain some charge between pulses, and a diode to prevent that charge from draining back into the rest of the circuit. A ping-pong ball serves as light diffuser, and the whole thing is hung up using a 3D-printed sheath which adds its own splash of color.

Solar garden lights are great basis for a cheap and easy introduction to electronics hacking. We’ve seen them turn into LED throwies, into a usable flashlight, or even to power an ATTiny microcontroller.

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Hexagrow Robot Packs A Serious Sensor Package

Automation is a lofty goal in many industries, but not always straightforward to execute. Welding car bodies in the controlled environment of a production line is relatively straightforward. Maintaining plants in a greenhouse, however, brings certain complexities due to the unpredictable organic processes at play. Hexagrow is a robot that aims to study automation in this area, developed as the final year project of [Mithira Udugama] and team.

The robot’s chassis is a very modern build, consisting of carbon fiber panels and 3D printed components. This kind of strength is perhaps overkill for the application, but it makes for a very light and rigid robot when the materials are used correctly.

Testing soil pH isn’t easy, but Hexagrow is up to the challenge.

It’s the sensor package where this build really shines, however. There’s the usual accoutrement of temperature and humidity sensors, and a soil moisture probe, as we’d expect. But there’s more, including an impressive soil pH tester. This involves a robotic arm with a scoop to collect soil samples, which are then weighed by a load cell. This is then used to determine the correct amount of water to add to the sample. The mixture is then agitated, before being tested by the probe to determine the pH level. It recalls memories of the science packages on Mars rovers, and it’s great to see this level of sophistication in a university project build. There’s even a LIDAR mounted on top for navigation purposes, though it’s not clear as to whether this sensor is actually functionally used at this point in development.

Plants can be demanding of their caretakers, so perhaps you’d best check you’re measuring your soil moisture correctly? Video after the break.

[Thanks to Baldpower for the tip!]

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