2026-01-23 00:30:50
[Kevin] admits that FreeCAD may not be the ideal tool for editing STL files. But it is possible, and he shares some practical advice in the video below. If you want to get the most out of your 3D printer, it pays to be able to create new parts, and FreeCAD is a fine option for that. However, sometimes you download an STL from the Internet, and it just isn’t quite what you need.
Unlike native CAD formats, STLs are meshes of triangles, so you get very large numbers of items, which can be unwieldy. The first trick is to get the object exactly centered. That’s easy if you know how, but not easy if you are just eyeballing it.
If you use the correct workbench, FreeCAD can analyze and fix mesh problems like non-manifold parts, flipped normals, and other issues. The example is a wheel with just over 6,000 faces, which is manageable. But complex objects may make FreeCAD slow. [Kevin] says you should be fine until the number of faces goes above 100,000. In that case, you can decimate the number of faces with, of course, a corresponding loss in resolution.
Once you are satisfied with the mesh, you can create a real FreeCAD shape from the mesh. The resulting object will be hollow, so the next step will be to convert the shape to a solid.
That still leaves many triangles when you really want flat surfaces to be, well, flat. The trick is to make a copy and use the “refine shape” option for the copy. Once you have a FreeCAD solid, you can do anything you can do in FreeCAD.
We’ve run our share of FreeCAD tips if you want more. There are other ways to tweak STLs, too.
2026-01-22 23:00:29
There’s little about building spacecraft that anyone would call simple. But there’s at least one element of designing a vehicle that will operate outside the Earth’s atmosphere that’s fairly easier to handle: aerodynamics. That’s because, at the altitude that most satellites operate at, drag can essentially be ignored. Which is why most satellites look like refrigerators with solar panels and high-gain antennas attached jutting out at odd angles.
But for all the advantages that the lack of meaningful drag on a vehicle has, there’s at least one big potential downside. If a spacecraft is orbiting high enough over the Earth that the impact of atmospheric drag is negligible, then the only way that vehicle is coming back down in a reasonable amount of time is if it has the means to reduce its own velocity. Otherwise, it could be stuck in orbit for decades. At a high enough orbit, it could essentially stay up forever.
There was a time when that kind of thing wasn’t a problem. It was just enough to get into space in the first place, and little thought was given to what was going to happen in five or ten years down the road. But today, low Earth orbit is getting crowded. As the cost of launching something into space continues to drop, multiple companies are either planning or actively building their own satellite constellations comprised of thousands of individual spacecraft.
Fortunately, there may be a simple solution to this problem. By putting a satellite into what’s known as a very low Earth orbit (VLEO), a spacecraft will experience enough drag that maintaining its velocity requires constantly firing its thrusters. Naturally this presents its own technical challenges, but the upside is that such an orbit is essentially self-cleaning — should the craft’s propulsion fail, it would fall out of orbit and burn up in months or even weeks. As an added bonus, operating at a lower altitude has other practical advantages, such as allowing for lower latency communication.
VLEO satellites hold considerable promise, but successfully operating in this unique environment requires certain design considerations. The result are vehicles that look less like the flying refrigerators we’re used to, with a hybrid design that features the sort of aerodynamic considerations more commonly found on aircraft.
This might sound like science fiction, but such craft have already been developed and successfully operated in VLEO. The best example so far is the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE), launched by the European Space Agency (ESA) back in 2009.
To make its observations, GOCE operated at an altitude of 255 kilometers (158 miles), and dropped as low as just 229 km (142 mi) in the final phases of the mission. For reference the International Space Station flies at around 400 km (250 mi), and the innermost “shell” of SpaceX’s Starlink satellites are currently being moved to 480 km (298 mi).
Given the considerable drag experienced by GOCE at these altitudes, the spacecraft bore little resemblance to a traditional satellite. Rather than putting the solar panels on outstretched “wings”, they were mounted to the surface of the dart-like vehicle. To keep its orientation relative to the Earth’s surface stable, the craft featured stubby tail fins that made it look like a futuristic torpedo.
Even with its streamlined design, maintaining such a low orbit required GOCE to continually fire its high-efficiency ion engine for the duration of its mission, which ended up being four and a half years.
In the case of GOCE, the end of the mission was dictated by how much propellant it carried. Once it had burned through the 40 kg (88 lb) of xenon onboard, the vehicle would begin to rapidly decelerate, and ground controllers estimated it would re-enter the atmosphere in a matter of weeks. Ultimately the engine officially shutdown on October 21st, and by November 9th, it’s orbit had already decayed to 155 km (96 mi). Two days later, the craft burned up in the atmosphere.
While GOCE may be the most significant VLEO mission so far from a scientific and engineering standpoint, the current record for the spacecraft with the lowest operational orbit is actually held by the Japan Aerospace Exploration Agency (JAXA).
In December 2017 JAXA launched the Super Low Altitude Test Satellite (SLATS) into an initial orbit of 630 km (390 mi), which was steadily lowered in phases over the next several weeks until it reached 167.4 km (104 mi). Like GOCE, SLATS used a continuously operating ion engine to maintain velocity, although at the lowest altitudes, it also used chemical reaction control system (RCS) thrusters to counteract the higher drag.
SLATS was a much smaller vehicle than GOCE, coming in at roughly half the mass. It also carried just 12 kg (26 lb) of xenon propellant, which limited its operational life. It also utilized a far more conventional design than GOCE, although its rectangular shape was somewhat streamlined when compared to a traditional satellite. Its solar arrays were also mounted in parallel to the main body of the craft, giving it an airplane-like appearance.
The combination of lower altitude and higher frontal drag meant that SLATS had an even harder time maintaining velocity than GOCE. Once its propulsion system was finally switched off in October 2019, the craft re-entered the atmosphere and burned up within 24 hours. The mission has since been recognized by Guinness World Records for the lowest altitude maintained by an Earth observation satellite.
As impressive as GOCE and SLATS were, their success was based more on careful planning than any particular technological breakthrough. After all, ion propulsion for satellites is not new, nor is the field of aerodynamics. The concepts were simply applied in a novel way.
But there exists the potential for a totally new type of vehicle that operates exclusively in VLEO. Such a craft would be a true hybrid, in the sense that its primarily a spacecraft, but uses an air-breathing electric propulsion (ABEP) system akin to an aircraft’s jet engine. Such a vehicle could, at least in theory, maintain an altitude as low as 90 km (56 mi) indefinitely — so long as its solar panels can produce enough power.
Both the Defense Advanced Research Projects Agency (DARPA) in the United States and the ESA are currently funding several studies of ABEP vehicles, such as Redwire’s SabreSat, which have numerous military and civilian applications. Test flights are still years away, but should VLEO satellites powered by ABEP become common platforms for constellation applications, they may help alleviate orbital congestion before it becomes a serious enough problem to impact our utilization of space.
2026-01-22 20:00:47
Although already having entered the territory of ‘retro gaming’, the Sony PlayStation 3 remains a notoriously hard to emulate game console. Much of this is to blame on its unique PowerPC-based Cell processor architecture, which uses a highly parallel approach across its asymmetric multi-core die that is very hard to map to more standard architectures like those in today’s x86 and ARM CPUs. This makes it even more amazing that the RPCS3 emulator team has now crossed the 70% ‘playable’ threshold on their compatibility list.
This doesn’t mean that you can fire up these games on any purported ‘gaming system’, as the system requirements are pretty steep. If you want any kind of enjoyable performance the recommended PC specifications feature an Intel 10th generation 6-core CPU, 16 GB of dual-channel RAM and a NVIDIA RTX 2000 or AMD RX 5000 series GPU or better.
It should be noted here also that the ‘playable’ tag in the compatibility list means that the game can be completed without game breaking glitches. Performance remains an issue, with very creative optimizations through e.g. the abuse of x86 SIMD instructions remaining the topic of research by the emulator developers. Yet as original PS3 hardware gradually becomes less available, the importance of projects like RPCS3 will become more important.
Header: Evan-Amos, Public domain.
2026-01-22 17:00:06
The Nintendo Wii first launched in 2006, and quickly became a fixture in living rooms around the world. It offered motion-controlled bowling, some basic internet features, and a pretty decent Zelda game. On top of all that, though, you could also use it to order a pizza, as [Retro Game Attic] demonstrates.
The Wii used to organize different features of the console into “channels.” Way back in the day, you could install the Demae Channel on your Wii in Japan, which would let you order fast food from various outlets using the Demaecan service.
The Demae Channel service was discontinued in 2017. However, it has since been resurrected by WiiLink, which is a homebrew project which replicates the functionality of the original Nintendo WiiConnect 24 and Wi-Fi Connection servers. As it stands, you can load the WiiLink version of the Demae Channel (or Food Channel) on to your Wii, and use it to order pizza from your local Domino’s Pizza. It only works in the United States and Canada right now, and there are no other restaurants available, at least until further development is completed to add JustEat compatibility. It’s not entirely clear how much of the functionality was recreated from the original Demae Channel; what is clear is that plenty of custom development has been done on the WiiLink version to integrate it with modern delivery services.
What’s so exciting about this is how well it actually works. The app perfectly nails the classic Wii Channel visual style. It also seems to integrate well with the Domino’s API for digital orders, even displaying simple updates on holiday opening hours and order times. Pricing data and images of the pizzas are all available right in the app, and you can even make modifications. It might be a gimmick… but it actually works. Notably, though, the app avoids any stickiness with handling payment—thankfully, pay-on-delivery is still legitimate in the pizza world in 2026.
Will this revolutionize how you order pizza on a daily basis? Probably not. Is it one of the coolest Wii hacks we’ve seen in a while? Undeniably. Video after the break.
2026-01-22 14:00:09
Creative clocks are a dime a dozen, even clocks that use binary have been created in nearly every format. [typo] promises a clever adaptation to the binary format, and it promises a more usable display. Using a combination of both traditional binary and digital gradients creates a usable and yet still nerdy fun clock.
[typo]’s clock fits the traditional binary counting method with the hours on the left side of its face. On the other hand, its right side presents a lighting gradient depending on the completion of the hour. While this is simple in principle, [typo] chose to correct what many don’t consider when deploying visual gradients. The human eye doesn’t see everything exactly as it is, which creates a rough logarithmic curve that gets corrected for in the binary/digital hybrid clock.
If you want something more mobile and still have that smidge of difficult time telling you, check out this minimalist wrist watch!
2026-01-22 11:00:02
One of the good things about simulating circuits is that you can easily change component values trivially. In the real world, you might use a potentiometer or a pot to provide an adjustable value. However, as [Ralph] discovered, there’s no pot component in LTSpice. At first, he cobbled up a fake pot with two resistors, one representing the top terminal to the wiper, and the other one representing the wiper to the bottom terminal. Check it out in the video below.
At first, [Ralph] just set values for the two halves manually, making sure not to set either resistor to zero so as not to merge the nets. However, as you might guess, you can make the values parameters and then step them.
By using .step you can alter one of the resistor values. Then you can use a formula to compute the other resistor since the sum of the two resistors has to add up to the pot’s total value. That is, a 10K pot will have the two resistors always add up to 10K.
Of course, you could do this without the .step and simply change one value to automatically compute both resistors if you prefer.
We’ve done our own tutorials with .step and parameters if you want a little more context. You can even use this idea to make your own custom pot component.
