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Hackaday Links: July 13, 2025

There’s interesting news out of Wyoming, where a coal mine was opened this week. But the fact that it’s the first new coal mine in 50 years isn’t the big news — it’s the mine’s abundance of rare earth elements that’s grabbing the headlines. As we’ve pointed out before, rare earth elements aren’t actually all that rare, they’re just widely distributed through the Earth’s crust, making them difficult to recover. But there are places where the concentration of rare earth metals like neodymium, dysprosium, scandium, and terbium is slightly higher than normal, making recovery a little less of a challenge. The Brook Mine outside of Sheridan, Wyoming is one such place, at least according to a Preliminary Economic Assessment performed by Ramaco Resources, the mining company that’s developing the deposit.

The PEA states that up to 1,200 tons of rare earth oxides will be produced a year, mainly from the “carbonaceous claystones and shales located above and below the coal seams.” That sounds like good news to us for a couple of reasons. First, clays and shales are relatively soft rocks, making it less energy- and time-intensive to recover massive amounts of raw material than it would be for harder rock types. But the fact that the rare earth elements aren’t locked inside the coal is what’s really exciting. If the REEs were in the coal itself, that would present something similar to the “gasoline problem” we’ve discussed before. Crude oil is a mixture of different hydrocarbons, so if you need one fraction, like diesel, but not another, like gasoline, perhaps because you’ve switched to electric vehicles, tough luck — the refining process still produces as much gasoline as the crude contains. In this case, it seems like the coal trapped between the REE-bearing layers is the primary economic driver for the mine, but if in the future the coal isn’t needed, the REEs could perhaps be harvested and the coal simply left behind to be buried in the ground whence it came.

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Simple Demo Shows The Potential Of Magnetic Gears

We’ve probably all used gears in our projects at one time or another, and even if we’re not familiar with the engineering details, the principles of transmitting torque through meshed teeth are pretty easy to understand. Magnetic gears, though, are a little less intuitive, which is why we appreciated stumbling upon this magnetic gear drivetrain demonstration project.

[William Fraser]’s demo may be simple, but it’s a great introduction to magnetic gearing. The stator is a block of wood with twelve bolts to act as pole pieces, closely spaced in a circle around a shaft. Both ends of the shaft have rotors, one with eleven pairs of neodymium magnets arranged in a circle with alternating polarity, and a pinion on the other side of the stator with a single pair of magnets. When the pinion is spun, the magnetic flux across the pole pieces forces the rotor to revolve in the opposite direction at a 12:1 ratio.

Watching the video below, it would be easy to assume such an arrangement would only work for low torque applications, but [William] demonstrated that the system could take a significant load before clutching out. That could even be a feature for some applications. We’ve got an “Ask Hackaday” article on magnetic gears if you want to dive a little deeper and see what these interesting mechanisms are good for.

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High Tech Tagging Adds Graffiti To Poles

[Akira] looks to increase his urban canvas by tagging poles which some custom hardware. If you’re looking to add some art to a lamp post, height becomes a problem. That’s where this little guy comes in. The remote-controlled pole climber includes a marker that leaves a trail as the device climbs and descends.

The rig clamps around a pole, with omnidirectional bearings on three sides of the four-sided frame. That last side is occupied by a rubber wheel mounted at a bit of an angle. When the motor turns the angle of the wheel causes the jig to rotate around the pole and climb at the same time. To come back down the motor is simply reversed. Xbee modules are used to make a rudimentary wireless control with a button for up and another for down. It looks like the marker is also mounted on a servo but we didn’t see a way to control when it is actually touching the pole. Perhaps you can figure it out by studying the clip after the jump.

We’ve seen projects that climb poles before. Among our favorites is the one that takes your bicycle with it.

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Ski Pole Persistence Of Vision

[Powder4u] wanted to make a persistence of vision display for his bicycle but with 50 cm of snow on the ground it’s hard to get out and ride right now. Instead he made this persistence of vision ski-pole accessory. We asked him to share some details and he obliged. It’s made using an Arduino compatible ATmega168, LEDs with resistors, and installed on some protoboard. The enclosure is a clear pencil case, which isn’t water tight but he’s tried to bolster that with some creative scotch tape placement. There’s no sensor to detect which direction the board is moving in so displaying alpha-numeric messages will have some issues, but as you can see he managed to display image data without issue.

We’re used to night skiing with floodlights along the slopes. This would be a fun little thing to have along with you on those dark lift rides.

Climbing Bike Storage Thwarts Thieves?

If you’ve got an expensive bike and don’t mind carrying around a whole bunch of extra weight in your courier bag you’ll like this concept. A design team built a pole-climbing bike rack in about 14 days. The video after the break shows the prototyping process as well as the finished “lock” in use. It’s a commercial for the company that employs the designers, but this is one kind of advert we don’t mind watching.

Square channel makes up the body of the device, with a set of Rollerblade wheels which grab a light pole and use three 12V gear motors for climbing. The controller is a wireless fob similar to those used for keyless entry on cars. In the video you can hear the cliché sound of a car alarm being set once the carrier reaches its finished height. Nice.

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