A Spinning Egg For Your Thoughts

Brushless motors are fascinating devices that come in all sorts of shapes and sizes, but you’ve probably never seen one in the form of a free-spinning shiny metal egg. Created by [David Windestål], [Giacomo Di Muro], and [Chad Kapper], the Motion Zero is part top, part brushless motor, and fully mesmerizing. Tech overview video after the break.

Like the classic Tippe Top toy, an ovoid shape like this shiny metal egg will stand on its end if it’s spun fast enough. To do this, the team embedded magnets in the metal egg, effectively turning it into a rotor. An array of 4 PCB coils under a smooth concave surface serves as the stator. Because the egg is not held in position by a shaft, hall effect sensors were incorporated to determine the position of the egg, and properly control the state of the coils to keep it spinning.

Recognizing how easy it was to get lost in thought while staring at a shiny spinning egg, the rest of the device was designed with meditation in mind. The top cover is a block of aluminum machined with ripple patterns, with ball bearings that slide between the ripples as the control interface. Additional hall effect sensors on the PCB determine the position of the balls to adjust the rotation speed and shut-off timer. You can even choose to make the egg move around or remain in one position. The main controller is an ESP32 module, which reads all the hall effect sensors and controls the coils via motor drivers.

The Motion Zero has made its debut on Kickstarter and already exceeded its initial funding goal. We like the creators’ willingness to share the inner workings of a product that manages to transform a simple concept into a mesmerizing piece of engineering artistry.

We’ve seen a good bit of [David Windestål]’s has a fascination with weird tech over the years, like racing belt sanders, fire breathing waterfowl, tri and bicopters. He even built a prop anti-drone RF cannon for a movie.

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Exploring Ground-Effect With A Quadcopter

The ground-effect (GE) refers to the almost mystical property where the interaction of the airflow around an aircraft’s wing and the ground massively increases efficiency due to the reduction of lift-dependent drag, perhaps best demonstrated by the Soviet Lun-class “ekranoplans” of the 1980s and 90s. Interestingly, this principle also applies to rotary aircraft, which led the [rctestflight] YouTube channel to wonder what would happen if a quadcopter were to be adapted for GE.

As noted on the Wikipedia entry for Ground-effect vehicle (GEV), it’s essential to have some kind of forward motion. With a rotorcraft like a helicopter or quadcopter this motion is already provided by the spinning propeller, which makes it noticeably easier to get the aircraft into the ground-effect. operating mode. Following the notion that the GE becomes noticeable at an altitude that’s dependent on the length of the aircraft’s wings, this got translated into putting the largest propellers available on the custom inverted-prop (to put them lower to the ground) quadcopter, to see what effect this would have on the quadcopter’s performance. As demonstrated by the recorded current drawn (each time with a fully charged battery), bigger is indeed better, and the GE effect is indeed very noticeable for a quadcopter.

Getting a usable GEV out of the basic inverted-prop quadcopter required some more lateral thinking, however, as it was not very easy to control this low to the ground. Here following design cues from skirtless hovercraft designs helped a lot, essentially drawing on the Coandă effect. Although this improved performance, at this point the quadcopter had been fitted with a fifth propeller for propulsion and was skidding about more like a skirtless hovercraft and less of a quadcopter.

Although great for scaring the living daylights out of unsuspecting water-based wildlife, what this unfortunately demonstrates is that GEVs are still hard, no matter which form they take. At the very least it does make for an excellent introduction into various aspects of aerodynamics.

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Powerful Nerf Blaster Aims To Fire 100 Darts Per Second

Nerf has made plenty of fully-automatic blasters over the years, but their toys typically lack punch, precision, and fire rate. [3DprintedLife] set about building a blaster to rectify that last shortcoming, aiming for design that could fire 100 darts per second.

The design uses half length darts which tend to fly a little nicer from high-powered blasters. It fires them using belts driven by powerful motors, similar to wheel blasters. The darts themselves are loaded into a drum magazine which has sliders to push the darts into the wheels as the drum rotates by.

It all sounds straightforward enough, but getting it all working in harmony is a challenge—particularly at a fire rate of 100 darts per second. The build video explains the trials and tribulations involved in getting near that fire rate, with darts getting shredded and magazines throwing out parts along the way.  A good helping of iterative design helps get everything playing nice, with the darts neatly leaving the magazine and flying downrange at great speed. The slow-motion videos of darts flying out of the blaster in rapid succession are a special treat.

Files are available via Onshape for those looking to dive deeper into the design. We’ve seen some other neat Nerf blasters before, too. Video after the break.

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Toy Bulldozer Becomes Epic Terrifying Lawnmower

Regular lawnmowers are a perfectly fine way to mow your lawn, but they can be a bit boring. They’re also not always the best at tackling thick brush and bushes. [rctestflight] has a solution to both of those problems, in the form of a plant-munching bulldozer.

The concept is simple — it starts with a hefty miniature RC bulldozer. Weighing in at 27 kilograms (60 pounds), the beast has actual functioning hydraulics to control the blade and plow. It struggles somewhat with traction, particularly in muddier conditions, and can’t really dig much, but it nonetheless looks the business.

As cool as it was, [rctestflight] decided to employ it for some real yard work by outfitting it with a mowing rig. The ‘dozer was outfitted with a pair of sawblades, run by twin brushless motors for plenty of grunt. That gave the bulldozer the ability to mow through not just lawn, but even thick blackberry bushes and two-foot high weeds.

It’s not great at steering, but it’s able to destroy thick brush with reckless abandon. Fundamentally, it looks like a very fun way to mow an overgrown yard.

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3D Printed RC Car Is Geared For Speed

You can always go out and buy an RC car off the shelf. However, it’s readily achievable to print your own design that has many of the features of off-the-shelf models, as demonstrated by [Jinan].

[Jinan] set about creating a rear-wheel-drive design with a low center of gravity for good handling. Two large 5.2 Ah batteries slung low in the chassis help keep the car planted when cornering. [Jinan] also developed a double-wishbone suspension setup up front to handle bumps with ease.

With his eyes on top speed, [Jinan] needed a drivetrain that could handle sustained high RPM operation without failure. During the development process, [Jinan] spent plenty of time learning about the mathematics behind gear shapes before relying on a built-in CAD generator to do the job for him. Armed with proper gearing, he focused on making sure the driveshafts and other links wouldn’t fail at speed.

[Jinan] doesn’t shy away from diving into the engineering of his design, analyzing failures and improving on his designs along the way. It’s no surprise his design was able to reach 66 km/h (41 MPH) after his rigorous development process.  It’s compelling watching, and a great way to learn something.

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Building A Hydraulic Lego Excavator Using Standard Pneumatic Cylinders

Everyone already knows that Lego Technic is pretty rad when it comes to existing, pre-made kits, but there’s also quite a bit of hacking potential left. One such area is the lack of hydraulics in Lego Technic, an egregious oversight that [Brick Technology] simply had to correct. His effort results in a partially hydraulic, fully remote-controlled excavator. Rather than a traditional gear hydraulic pump as you’d expect in a real-life excavator, a custom peristaltic pump is used to move the fluid to the hydraulic cylinders (rams for our British and Oceanic friends).

The undercarriage is (sadly) purely electrical, with a slip-ring providing power to the electric final drives in the tracks, enabling it to spin around endlessly without limitations. Where the hydraulics come into play is in the excavator’s arm, with two hydraulic lift cylinders on the boom, one cylinder to control the stick, and a final cylinder to control the bucket. Rather than a hydraulic switch, the setup is simplified by using a single peristaltic pump per cylinder circuit.

Remote control and power are provided using the rather chonky BuWizz 3.0 Pro, which offers a wireless control link (here controlled using BrickController 2 on Android). Although original Lego cylinders were used, these are only intended for pneumatics, where it’s hoped that the used mixture of water and windscreen wiper fluid will prevent corrosion.

(Thanks to [Keith Olson] for the tip)

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A Bubble Machine Built From Scrap

Not every project has to be an AI-powered particle accelerator using lasers. Sometimes simple projects can be very satisfying, and a simple project can be a great gateway to introduce a friend or a child to our hacker ways. That’s why we noticed [Crazy Science’s] bubble machine upcycled from a CD and a water bottle. It isn’t likely to figure in anyone’s Ph.D. dissertation any time soon, but that isn’t the point

Once you see the pictures, you can probably figure out how to build it. For extra points, consider scrounging everything from stuff you already have. We were curious about drilling holes in the CD as we’d imagine they’d crack with an ordinary drill bit. Apparently, a soldering iron will pierce the disk, but we would advise doing that in a well-ventilated area.

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