Building A Rad Super Capacitor RC Plane

December 25, 2023 by Lewin Day 15 Comments

[Tom Stanton] is a fan of things like rubber band planes, and has built many of his own air-powered models over the years. Now, he’s built a model powered by a supercapacitor for a thoroughly modern twist on stored-energy flying toys.

It’s not a wholly original idea; [Tom] was inspired by a toy he bought off-the-shelf. His idea, though, was to make one that could be hand-cranked to charge it to make it more like the rubber-band planes of old. He thus built his own geared generator for the job using a big pile of magnets and 3D printed components. It’s capable of putting out around 17 volts when cranked at a reasonable speed. Hooked up to the toy plane, his hand-crank generator was able to fully charge the plane in just a few turns.

His generator was really overkill for the small toy, though. Thus, he elected to build himself a much larger supercapacitor-powered model. He wired up a pack of six supercapacitors in series, designed for roughly 18 volts. The pack was given balance leads to ensure that no individual capacitor was charged beyond its 3.0 V rating. The pack was placed inside a nice aerodynamic printed fuselage. The plane was then given a brushless motor and prop, speed controller, servos, and an RC receiver. Indeed, far from a simple throwable model, it’s a fully flyable RC plane.

The plane is quite a capable flyer with plenty of power, but a fairly short run time of just under two minutes. Though, with that said, it can be recharged in just about that same amount of time thanks to its supercapacitor power supply. [Tom] reckons it should be capable of a 1:1 crank time to flight time ratio in ideal conditions.

Supercapacitors are super cool, but we don’t see enough of them. They’ve popped up here and there, and obviously have many important applications, but we’re not sure they’ve had a real killer app in the consumer space. XV Racers were killer fun, though. Continue reading “Building A Rad Super Capacitor RC Plane” →

3D Printing With Plastic Cutlery

December 25, 2023 by Al Williams 18 Comments

How many plastic spoons, knives, and forks do you think we throw away daily? [Stefan] noted that the compostable type is made from PLA, so why shouldn’t you be able to recycle it into 3D printing stock? How did it work? Check it out in the video below.

[Stefan] already has a nice setup for extruding filament. However, unsurprisingly, it won’t accept spoons and forks directly. A blender didn’t help, so he used an industrial plastic shredder. It reduced the utensils to what looked like coarse dust, which he then dried out. After running it through the extruder, the resulting filament was thin and brittle. [Stefan] speculates the plastic was set up for injection molding, but it at least showed the concept had merit.

In a second attempt, he cut the ground-up utensils with fresh PLA in equal measures. That is, 50% of the mix was recycled, and half was not. That made much more usable filament. So did a different brand of compostable plasticware.

The real test was to take dirty plasticware. This time, he soaked utensils in tomato sauce overnight. He cleaned, dried, and shredded the plastic. This time, he used 20% new PLA and some pigment, as well. We aren’t sure this is worth the effort simply on economics, but if you are committed to recycling, this might be worth your while.

It always seems like it should be easy to extrude filament. Until you try to do it, of course. Recycling plastic bottles is especially popular.

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Is This 3D Printed Third Arm Useful? Maybe?

December 25, 2023 by Lewin Day 11 Comments

Humans have two arms, and we do pretty good things with them. More is surely better, though, right? With that in mind, [Emily The Engineer] set out to make a third arm for popular YouTuber [This Old Tony], and our primary question is this: is it actually useful?

The basic design is based around a strapped-on arm brace, which mounts the additional appendage to the wearer’s forearm. It uses a motor-driven geared mechanism to open and close a gripper, but the first revision was incredibly slow to open and close, to the point of being almost useless. Changing out the threaded rod that drives the mechanism massively sped up the gripper, much to [Emily]’s satisfaction. Strength and mounting upgrades got it to the point where it could actually be used to lift objects like spray cans and bricks. Ultimately, though, the arm mount and controls do kind of prevent the user from using their left hand when they have the third hand fitted.

It’s a fun project, if not exactly a useful one, even if [Emily] does use it to carry extra grocery bags . It does have us wondering if some kind of shoulder or backpack-mounted arms could be useful, though. It’s certainly not up to the standards of modern prosthetic, but we do love the idea of human augmentation with additional robot limbs. Here’s hoping technology advances further to make builds like this more capable in future!

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Promethean Matches: The Ancestor To Modern Matches

December 25, 2023 by Maya Posch 7 Comments

The history of making fire at will is a long and storied one, stretching back to the days when we’d rub wooden sticks together, or use flint and steel to ignite tinder. An easier, albeit vastly more expensive and dangerous alternative came in the 19th century when chemists discovered auto-ignition using a potassium chlorate mixture and sulfuric acid. This method was refined and later patented by Samuel Jones in 1828 as the ‘promethean match’ after the God of Fire, Prometheus, which is the topic of a recent [NurdRage] chemistry video.

Using practically the same recipe of potassium chlorate and sugar as in the 19th century, [NurdRage] uses paper straws to contain this powder. Glue is used to section the paper straw into two compartments and seal in the components, with the smaller compartment used for a glass capsule containing sulfuric acid. This vial was produced from the tip of a glass pipette, using a hot flame to first seal the tip, then detach and seal the other end of the tip, resulting in the sulfuric acid capsule, ready to be added to the second compartment.

The moment this glass capsule is crushed, the sulfuric acid will soak into the paper, reaching the large compartment with the potassium chlorate and sugar mixture, causing a strongly exothermic reaction that ignites the paper. Yet as simple as this sounds, [NurdRage] found the three matches he made to be rather fickle, with one igniting beautifully after crushing the capsule with pliers, while one did nothing and the remaining match decided to violently explode rather than burn.

Considering the immense manual labor involved in making these matches, they never were very popular, and were quickly replaced by strike-anywhere matches, followed by safety matches, none of which require you to carry fragile glass capsules containing sulfuric acid with you. As a chemistry experiment, it is however a total blast that will set any boring chemistry class on fire.

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Radiochat Is A Simple LoRa Interface Over WiFi

December 25, 2023 by Lewin Day 20 Comments

LoRa is often talked about as a potentially useful solution for emergency communication. The problem is, few of us are running around with LoRa hardware on a day-to-day basis. Student [William Barkoff] designed the Radiochat device as a simple tool that could pair with virtually anything over WiFi, and allow it to send and receive LoRa messages.

Radiochat is based on the Raspberry Pi Pico W, and uses the microcontroller’s wireless hardware to communicate with other devices. It provides a WiFi network that devices like laptops or smartphones can connect to. The Pico serves up a simple web page which accepts text input. Type in a message and hitting enter and the Pico will command a LoRa radio module over SPI to send that message out over the airwaves. It can then be picked up by another Radiochat module which displays the message on its own webpage.

It’s in an early state of development, and the demo video shows there are still some bugs to work out. Ultimately, though, it could be a cheap battery-powered device that lets smartphones and laptops chat over LoRa in remote areas. Indeed, [William’s] trips to New Mexico on model rocketry expeditions were a big inspiration for the project.

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3D Printing Stacks

December 24, 2023 by Al Williams 3 Comments

There is a big difference between building one of something and building, say, 100 of the same item. It isn’t surprising, then, that 3D printing in bulk differs from printing one object at a time. Of course, filling up your build plate is not a new idea. But [Keep Making] wants to encourage you to think in three dimensions and fill up your build volume in the Z axis, as well.

When you fill your X and Y axes, it is easy to see how the parts separate. But with stack printing, you must separate the parts from different layers. Each part has a single-layer gap, and the top surfaces are ironed for a better finish. Sometimes the prints may stick, and the video shows how to use a screw to pop off recalcitrant prints. The technique produces one side that isn’t as nice a finish as the other side, but it isn’t bad, and for many applications, you don’t care, anyway.

Before you get too excited about your own designs, you might try a simple test file and get your print settings dialed in. Obviously, if you need just two or three copies of something small, it is easier to step and repeat them across the build surface. But if you need to maximize your throughput or make multiple copies of large objects, this might be the technique for you.

Looks like an interesting technique that doesn’t require you to do anything strange like, say, waterproof your printer. No strings attached.

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Hidden Wall-Mount Table Looks Like Hanging Art

December 24, 2023 by Lewin Day 13 Comments

If you live in a compact space, sometimes you have to get creative with your furniture to make the most of it. This wall-hanging table design from [diyhuntress] is perfect for those situations where you need a table, but you don’t want it taking up the whole room when it’s not in use. Plus, it’s kinda stealthy, which makes it even more fun!

The table is a folding design, with a flat wooden top, and an equally-sized supporting leg that goes down to the ground. The other end of the table is supported by a frame on the wall, which also contains several shelves for small objects. The trick is that the table top and support are hinged together, so that they can fold up and sit in front of the shelves, essentially hanging the whole assembly from the wall. Even better, by painting a simple artwork on the support, the whole thing just looks like a decor piece with no clue as to its hidden functionality.

It’s a fun build, and one that you could easily knock out in a weekend with some basic woodworking skills. We’ve featured some other nifty shelf designs before, too. Just remember, too – a neat and tidy space is a boost to your hacker productivity, so don’t rule this out for your own use!

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