TechyMagThings

This custom enclosure for a 64×64 RGB LED matrix by [Davisan1001] not only provides a mount point for a Raspberry Pi, but presents a clean and smooth face with square pixels thanks to a 3D-printed grid, some parchment paper, and a sheet of clear plastic.

The first clever thing in this design is the way [Davisan1001] created the grid that acts as a light blocker for each LED in the matrix, preventing light from “spilling” over into its neighbors. Instead of designing the grid from scratch, the solution was just to leverage slicer settings. By printing a flat square with a grid pattern infill and zero solid top and bottom layers, the slicer creates the grid all by itself. A little trial and error was required to get the spacing just right, but it seems to have worked out fine. We’re not sure it’s better than designing a grid in CAD, but it was certainly a clever way to avoid having to do so.

[Davisan1001] also struggled to find an effective and economical solution for a diffuser. Certainly, high-quality diffuser films are available for sale, as are specialty acrylic sheets, but surely there was some household DIY option to do the trick. A sheet of plain white paper blocks too much light. Wax paper handles poorly, and off-angle viewing is poor. The sweet spot was parchment paper.

Parchment paper is commonly used in baking and is thin, easy to handle, flat and even in color, and just opaque enough to act as an effective diffuser while still transmitting enough light to not impede clarity. Cover the LED matrix with the 3D-printed grid, lay parchment paper over that, cover with a sheet of clear plastic, and the job is done.

Light diffusion can be tricky to get just right in a DIY project, and what works for one application won’t necessarily work for another. Our community had loads of suggestions on different solutions, so consider this one more idea to try the next time you have a project that calls for it.

After the [Slow Mo Guys] acquired a 168 TB Seagate LaCie Thunderbolt 3-based RAID storage system back in 2019 to store their video footage, they were obviously slightly miffed when suddenly it would just refuse to power up. Naturally the device was now out of warranty, the product itself no longer produced and Seagate support was less than supportive, ergo they sent the device to [Mend it Mark] for an attempted repair.

At first inspection the device appeared to be basically unresponsive, with none of the four fans running and no signs of life other than a few lit LEDs on the main PCB after supplying power to it. After full disassembly and with no repair guide or schematics to go by [Mark] had to start from basics, first diagnosing whether all the power rails were turning on, which they weren’t.

Eventually this led to the NXP LPC11U6x-series MCU which acts as the main power management and monitoring chip in the system. [Mark] deduced that this MCU wasn’t turning on all the power rails because it was waiting for a signal from the fan controllers on the SATA backplane. With the MCU sending the right signals here, and the fans all working when directly supplied with power, ultimately it turned out that a single SI2319 or similar P-channel MOSFET in SOT-23 package near one of the fan connectors had gone faulty.

Replacing this one MOSFET seems to have fixed the RAID array, with it now happily powering up, although the real test will be once the [Slow Mo Guys] start shoving the HDDs back into it. Assuming that this was the sole fault in the system, then it was a very cheap fix in terms of materials. It’s a real shame that repair guides or schematics aren’t made available for devices like this, even if just after they stop being produced.

A fun trick with a pole is to try to balance it so that it can stand on one end. This can be done in a few ways, such as by exerting a force on either end to counterbalance any force that threatens to make it fall over. The approach that [Peter Ryseck] chose was to cobble together what is effectively a flying drone for on top of a standing pole, without cheating such as by simply lifting it off the ground.

Getting to the point where the drone could react quickly enough to changes in the pole’s orientation was the hardest part, as the quieter, larger propellers also have a lot more inertia. This ruled out using 10″ blades, while triple 5″ blades seemed to work well enough. For the avionics a standard quadcopter control board and software is used, with the programming such that it’ll react appropriately without causing additional instabilities.

Naturally making this work took some trial and error, with issues like oscillations plaguing the system. One unexpected problem was that the pole – taken from a pool fishing net – was flexible enough to add its own instabilities to the system. In the video all these issues and their solutions are explained in detail, along with the ultimate result. One very neat solution here for example is to have the pole lean into the wind, which is a more stable configuration than insisting on having the pole be at a perfect ninety degrees with the ground.

Delidding a CPU involves removing the integrated heat spreader (IHS) that’s put over the bare die and the substrate that it is mounted on. The reason for this is usually to improve cooling performance, as the IHS is effectively a small heatsink between the die and the large heatsink, adding more problematic thermal interfaces. If delidding is done improperly it can cause severe damage to the substrate, as in the case of a very nice 1.3 GHz Tualatin Pentium III CPU that [Bits und Bolts] got in an eBay lot with nasty delidding damage.

With the delidding enthusiast presumably having used brute force and ignorance combined with a prying implement, around a dozen of tiny traces on the substrate got severed, requiring tedious trace repair to fix. After confirming that with the severed traces the CPU is indeed busted, enough of the soldermask is removed to make a repair.

Any traces that were still good got covered with soldermask, while for the remainders the thinnest available copper wire was used to create new traces. Although very much doable with a good microscope and a steady hand, this is definitely one of those things that’s much easier to prevent than to fix.

With IHSes having become standard on CPUs, delidding continues to this day, with increasing risks of severed traces and ripped-off capacitors should it go wrong. Although those newer CPU substrates are probably not repairable, repairing these older CPUs instead of tossing them as e-waste seems plausible at least.

Large prints have a risk of warping, by which we mean corners can lift off the print bed as the object sort of curls inward on itself. It’s not always due to poor filament quality or an unclean build plate. Sound like something you’ve dealt with? Check out this handy roundup to understand why it happens, and learn ways to prevent it.

The reason some objects have trouble while others don’t is physics. Deposited plastic shrinks ever so slightly as it cools, and some shapes — like wide, flat surfaces with sharp corners — are worse for this than others. This sort of problem is what the guide addresses with a number of techniques.

Some are simple, like turning on brims which increases an object’s footprint. This increased surface area offers more adhesion, but also increases heat transfer from the print bed into the model, slowing the cooling process. Thinner walls and an altered infill pattern is another option. Other techniques are more complex.

The most effective methods involve modifying the model itself to reduce or eliminate stress points. One such method is to break the model’s footprint into multiple zones with a shallow grid. Instead of one big flat bottom, the object has multiple smaller ones. Because big flat areas are more susceptible to warping than small ones, turning the bottom into a grid pattern helps spread those stresses out and prevent lifting.

If you design your own models, you’ll find several design tips worth keeping in mind. It’s always smart to practice good DFM (Design For Manufacturability) which means taking 3D printer strengths and weaknesses into account when designing an object. In this case, it can help prevent print failures. Good DFM can also make parts much, much stronger just by designing in the right features.

After getting called out in the field to troubleshoot a large PV solar installation, [Derek] found himself suddenly in the midst of an arc flash, causing burns all over his face and arms. In a recent video he goes over the scenario that led up to this unfortunate event, as the holes in the Swiss cheese slowly lined themselves up, culminating in a high-current 480 VDC discharge nearly giving [Derek] a fatal embrace.

Despite being a professionally trained and certified professional, being called out to diagnose a weird issue on a slightly unusual solar farm’s electrical installation already worked against him. After having spent some time doing said troubleshooting, he finally tracked down the auxiliary transformer that normally powers the low-voltage gear, along with the spicy parts that should absolutely be unpowered after flipping the breaker into the ‘off’ position.

Testing for no power confirmed that the power had indeed been cut, which was when the wiring that normally connects the auxiliary transformer was spotted still lying just out of reach in the back of the cabinet. Clearly this was the cause behind one of the issues that the owner had been having.

This was when [Derek] decided to go to the light reach for this spool of wiring with a pair of pliers, into the – as it turned out – still live high-voltage side. One massive arc flash and hospital recovery later, [Derek] learned that the layout of the lines in the cabinet were different from usual, with the position of the roll of loose wiring being a potential hint that something was off.

The problem here was one of habituation, and the assumption that the system that he was working on was de-energized. The reason that he’s still with us being that the pliers acted as the current path instead of his body, and the arc flash cooked only the exposed parts of his skin, being mostly parts of his face and his hands.

Terrifyingly, [Derek] was working alone, and was forced to dial 911 somehow, with fingers that no longer registered on the iPhone’s touch screen on account of the skin having been turned into charcoal. While he doesn’t remember exactly how he managed to reach 911, it’s likely that the voice assistant finally connected him. The property owner also arrived and did what he could do to help before the ambulance arrived.

Overall, the lesson here is that complacency and assumptions are the killers here. Even if the layout of a high-voltage circuit is different in a way that makes no sense and there ought to be industry standards, when it’s you reaching into that cabinet such trivial details matter less than having ensured that there’s absolutely no power on anything, even if you know that there shouldn’t be. Reality only has to disagree with you once there.

[Derek] was lucky in the sense that the cabinet mostly shielded him from the arc flash’s intense heat, but over 19% of his skin was still burned, requiring skin grafts and an ongoing, very painful recovery. By sharing his story he hopes that he can prevent at least one other person reaching into that cabinet with some pliers for that ‘let me just quickly…’ moment.

A surprising number of things we use in everyday life retain most of their design cues from their 19th century ancestors. The bicycle retains the same basic design as it had in 1890, as does the sewing machine, the toilet, the car, and of course, the keyboard and the QWERTY layout from old typewriters. But we aren’t doomed to have our technology perpetually living in the past. [Paul] wanted a keyboard designed around human hands, rather than being designed around a machine, so he built this unique split keyboard.

The design of this specific keyboard went through around 50 iterations before he was comfortable with it. Other design goals here were for it to be portable, and the split nature of this certainly makes it more compact as does the use of low-profile switches. Each finger’s column is angled and spaced based on the needs of that finger, with the ring finger keys sitting higher and the index finger columns angled inward. Each thumb has access to three keys, one of which is the spacebar and the other two layer keys, which is what enables this design to get down to only 36 total keys.

When thinking about it for any length of time, the modern keyboard’s design holdovers from the 1800s are fairly wasteful compared to this split, ergonomic version. Especially when looking at the spacebar, which ties up both thumbs and only performs a single task, there’s a lot of opportunity for modern designs to be more efficient, more portable, and easier on one’s body. Feel free to take this to the extreme and use all three dimensions, as long as you aren’t particularly concerned with portability.