Denim Epoxy Table Is A Work Of Art

July 27, 2023 by Lewin Day 34 Comments

Epoxy has become a hugely popular material in the woodworking and furniture worlds. Who doesn’t love glossy, translucent finishes, after all? [Cam] recently spotted some neat combinations of epoxy with denim, and decided to see if he could replicate the technique to create a very unique desk. We’d say he succeeded.

A significant amount of material was involved, with [Cam] claiming he used 1,000 square feet of denim and 20 gallons of epoxy. The denim was sourced as a bulk roll, making it easy to cut to the proper size to make the desk. Liquid Glass epoxy was used for its visual qualities and its hard-wearing nature.

Combining the two materials was a challenging task. The 50 layers of denim had to be squeegeed one at a time to remove excess epoxy, a process made harder by the thickness of the material. Once all laid up, the stack of denim was compressed between sheets of wood, leading to an epoxy spill of monumental proportions.

Regardless, when the final desk was cleaned up and polished, the results were well worth the trouble. It looks like some kind of crazy denim gem thanks to the rich shine and perfect grain. It’s a material we’d like to play with ourselves.

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Exploring Tropical Rainforest Stratification Using Space-Based LiDAR

July 27, 2023 by Maya Posch 11 Comments

GEDI is deployed on the the Japanese Experiment Module – Exposed Facility (JEM-EF). The highlighted box shows the location of GEDI on the JEM-EF.

Even though it may seem like we have already explored every single square centimeter of the Earth, there are still many areas that are practically unmapped. These areas include the bottom of the Earth’s oceans, but also the canopy of the planet’s rainforests. Rather having herds of explorers clamber around in the upper reaches of these forests to take measurements, researchers decided to use LiDAR to create a 3D map of these forests (press release).

The resulting GEDI (Global Ecosystem Dynamics Investigation) NASA project includes a triple-laser-based LiDAR system that was launched to the International Space Station in late 2018 by CRS-16 where it has fulfilled its two-year mission which began in March of 2019. Included in the parameters recorded this way are surface topography, canopy height metrics, canopy cover metrics and vertical structure metrics.

Originally, the LiDAR scanner was supposed to be decommissioned by stuffing it into the trunk of a Dragon craft before its deorbit, but after NASA found a way to scoot the scanner over to make way for a DOD payload, the project looks to resume scanning the Earth’s forests next year, where it can safely remain until the ISS is deorbited in 2031. Courtesy of the ISS’s continuous orbiting of the Earth, it’ll enable daily monitoring of its rainforests in particular, which gives us invaluable information about the ecosystems they harbor, as well as whether they’re thriving or not.

Hopefully after its hibernation period the orbital LiDAR scanner will be back in action, as the instrument is subjected to quite severe temperature changes in its storage location. Regardless, putting LiDAR scanners in orbit has to be one of those amazing ideas to help us keep track of such simple things as measuring the height of trees and density of foliage.

A Wigglegram Lens With Variable Aperture

July 27, 2023 by Lewin Day 6 Comments

Wigglegrams are those weird animated pictures you’ve seen that seem to generate a 3D-like effect. [scealux] had built lenses to take such pictures before, but wanted to take things to the next level. Enter the Wigglegram Lens, version 2.

In building a new lens for the Open Sauce ’23 event, [scealux] wanted to get variable aperture working, while also improving focus speed. The lens was also intended for use with a Sony A7R3. Unlike his previous effort, this lens would only work on the full-frame Sony FE mount cameras.

The lens uses a bevy of 3D printed parts, along with plastic lenses salvaged from old disposable cameras. When assembled, it takes three photos simultaneously on one single frame. They can then be reassembled into a Wigglegram by post-processing on a computer. The results are grainy and rough, but yet somehow compelling.

If you want to see [scealux]’s original build for Sony E-mount cameras, we covered it here. Video after the break.

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A Simple One-Handed Solder Feeder

July 27, 2023 by Lewin Day 46 Comments

Soldering can get frustrating when you’re working fast. It often feels like you don’t have enough hands, particularly on jobs where you need to keep feeding solder in a hurry. To solve that issue, [mulcmu] developed a simple one-handed solder feeder.

The solder is fed out of the tip by simply dragging it with the thumb.

The intended use-case is for busy work like soldering long pin headers. The one-handed device allows solder to be continually fed while the other hand uses the soldering iron. It solves a long-running problem for [mulcmu], after their experiments with techniques inspired by TIG welding came to nought.

The design uses a pen-like form factor. A 3D-printed hollow tube has a wire ferrule inserted in the end, which serves as the tip of the device through which solder is fed. The tube has a cutaway, which allows the user to feed solder through using an easy motion of the thumb. The solder itself is fed from a spool in a regular bench top holder. If more slack is required in the solder feed, one simply pins the solder down in the device and tugs to draw more out.

If you find yourself regularly soldering repetitive jobs by hand, this could be a gamechanger for you. Those working in through-hole would be perhaps best served by this device. Meanwhile, if you’ve got nifty tool hacks of your own to share, don’t hesitate to let us know!

Magnetic Gearbox, Part 2: Axial Flux Improves Performance

July 27, 2023 by Dan Maloney 13 Comments

The number of interesting and innovative mechanisms that 3D printing has enabled always fascinates us, and it’s always a treat when one of them shows up in our feeds. This axial flux magnetic gearbox is a great example of such a mechanism, and one that really makes you think about possible applications.

The principles of [Retsetman]’s gearbox are simple for anyone who has ever played with a couple of magnets to understand, since it relies on that powerful attractive and repulsive force you feel when magnets get close to each other. Unlike his previous radial flux gearbox, which used a pair of magnet-studded cylindrical rotors nested one inside the other, this design has a pair of disc-shaped printed rotors that face each other on aligned shafts. Each rotor has slots for sixteen neodymium magnets, which are glued into the slots in specific arrangements of polarity — every other magnet for the low-speed rotor, and groups of four on the high-speed rotor. Between the two rotors is a fixed flux modulator, a stator with ten ferromagnetic inserts screwed into it.

In operation, which the video below demonstrates nicely, the magnetic flux is coupled between the rotors by the steel inserts in the stator so that when one rotor moves, the other moves at a 4:1 (or 1:4) ratio in the opposite direction. [Retsetman] got the gearbox cranked up to about 8,500 RPM briefly, but found that extended operation at as little as 4,000 RPM invited disaster not due to eddy current heating of the inserts or magnets as one might expect, but from simple frictional heating of the rotor bearings.

Torque tests of the original gearbox were unimpressive, but [Retsetman]’s experiments with both laminated stator inserts and more powerful magnets really boosted the output — up to a 250% improvement! We’d also like to see what effect a Hallbach array would have on performance, although we suspect that the proper ratios between the two rotors might be difficult to achieve.

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Did TETRA Have A Backdoor Hidden In Encrypted Police And Military Radios?

July 27, 2023 by Lewin Day 42 Comments

Encrypted communications are considered vital for many organizations, from military users to law enforcement officers. Meanwhile, the ability to listen in on those communications is of great value to groups like intelligence agencies and criminal operators. Thus exists the constant arms race between those developing encryption and those desperately eager to break it.

In a startling revelation, cybersecurity researchers have found a potentially intentional backdoor in encrypted radios using the TETRA (TErrestrial Trunked RAdio) standard. TETRA equipment is used worldwide by law enforcement agencies, military groups, and critical infrastructure providers, some of which may have been unintentionally airing sensitive conversations for decades.

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ESP32 Freezer Alarm Keeps Tabs On Tricky Door

July 27, 2023 by Lewin Day 31 Comments

Leaving your freezer door open accidentally is a great way to make a huge mess in the kitchen. [Guy Dupont] had a freezer that would regularly fail to close properly, and was sick of the regular meltdown events. Thus, he whipped up a very digital solution.

The build combines an ESP32 with a reed switch, which is activated by a magnet on the freezer door. If the freezer door is open, the reed switch similarly remains open. The ESP32 checks the switch status every few minutes, and if the door remains open for two consecutive checks, it raises the alarm. A notification is sent to [Guy] via WiFi so that he can rectify the situation. The rig runs off a 400 mAh battery, which lasts for just over three weeks running door checks at two minute intervals.

Based on [Guy]’s YouTube video, it appears the freezer door is jamming up against the wall. Perhaps shoving the freezer into a better position would help, though we suspect he would have thought of that first. And, in his own words, “That would be a very boring YouTube video, wouldn’t it?”

It’s not the first fridge alarm we’ve featured, and it won’t be the last, refrigeration gods willing.

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