Author: Dan Maloney

3283 Articles

Retrotechtacular: The Tyranny Of Large Numbers

January 30, 2025 by 3 Comments

Although much diminished now, the public switched telephone network was one of the largest machines ever constructed. To make good on its promise of instant communication across town or around the world, the network had to reach into every home and business, snake along poles to thousands of central offices, and hum through the ether on microwave links. In its heyday it was almost unfathomably complex, with calls potentially passing through thousands of electronic components, any of which failing could present anything from a minor annoyance to a matter of life or death.

The brief but very interesting film below deals with “The Tyranny of Large Numbers.” Produced sometime in the 1960s by Western Electric, the manufacturing arm of the Bell System, it takes a detailed look at the problems caused by scaling up systems. As an example, it focuses on the humble carbon film resistor, a component used by the millions in various pieces of telco gear. Getting the manufacturing of these simple but critical components right apparently took a lot of effort. Initially made by hand, a tedious and error-prone process briefly covered in the film, Western Electric looked for ways to scale up production significantly while simultaneously increasing quality.

While the equipment used by the Western engineers to automate the production of resistors, especially the Librascope LGP-30 computer that’s running the show, may look quaint, there’s a lot about the process that’s still used to this day. Vibratory bowl feeders for the ceramic cores, carbon deposition by hot methane, and an early version of a SCARA arm to sputter gold terminals on the core could all be used to produce precision resistors today. Even cutting the helical groove to trim the resistance is similar, although today it’s done with a laser instead of a grinding wheel. There are differences, of course; we doubt current resistor manufacturers look for leaks in the outer coating by submerging them in water and watching for bubbles, but that’s how they did it in the 60s.

The productivity results were impressive. Just replacing the silver paint used for terminal cups with sputtered gold terminals cut 16 hours of curing time out of the process. The overall throughput increased to 1,200 pieces per hour, an impressive number for such high-reliability precision components, some of which we’d wager were still in service well into the early 2000s. Most of them are likely long gone, but the shadows cast by these automated manufacturing processes stretch into our time, and probably far beyond.

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Cool Kinetic Sculpture Has Tooling Secrets To Share

January 29, 2025 by 8 Comments

Occasionally, we get a tip for a project that is so compelling that we just have to write it up despite lacking details on how and why it was built. Alternatively, there are other projects where the finished product is cool, but the tooling or methods used to get there are the real treat. “Homeokinesis,” a kinetic art installation by [Ricardo Weissenberg], ticks off both those boxes in a big way.

First, the project itself. Judging by the brief video clip in the reddit post below, Homeokinesis is a wall-mounted array of electromagnetically actuated cards. The cards are hinged so that solenoids behind them flip the card out a bit, making interesting patterns of shadow and light, along with a subtle and pleasing clicking sound. The mechanism appears to be largely custom-made, with ample use of 3D printed parts to make the frame and the armatures for each unit of the panel.

Now for the fun part. Rather than relying on commercial solenoids, [Ricardo] decided to roll his own, and built a really cool CNC machine to do it. The machine has a spindle that can hold at least eleven coil forms, which appear to be 3D printed. Blank coil forms have a pair of DuPont-style terminal pins pressed into them before mounting on the spindle, a job facilitated by another custom tool that we’d love more details on. Once the spindle is loaded up with forms, magnet wire feeds through a small mandrel mounted on a motorized carriage and wraps around one terminal pin by a combination of carriage and spindle movements. The spindle then neatly wraps the wire on the form before making the connection to the other terminal and moving on to the next form.

The coil winder is brilliant to watch in action — however briefly — in the video below. We’ve reached out to [Ricardo] for more information, which we’ll be sure to pass along. For now, there are a lot of great ideas here, both on the fabrication side and with the art piece itself, and we tip our hats to [Ricardo] for sharing this.

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Big Chemistry: Catalysts

January 28, 2025 by 19 Comments

I was fascinated by the idea of jet packs when I was a kid. They were sci-fi magic, and the idea that you could strap into an oversized backpack wrapped in tinfoil and fly around was very enticing. Better still was when I learned that these things weren’t powered by complicated rockets but by plain hydrogen peroxide, which violently decomposes into water and oxygen when it comes in contact with a metal like silver or platinum. Of course I ran right to the medicine cabinet to fetch a bottle of peroxide to drip on a spoon from my mother’s good silverware set. Needless to say, I was sorely disappointed by the results.

My little impromptu experiment went wrong in many ways, not least because the old bottle of peroxide I used probably had little of the reactive compound left in it. Given enough time, the decomposition of peroxide will happen all by itself. To be useful in a jet pack, this reaction has to proceed much, much faster, which was what the silver was for. The silver (or rather, a coating of samarium nitrate on the silver) acted as a catalyst that vastly increased the rate of peroxide decomposition, enough to produce jets of steam and oxygen with enough thrust to propel the wearer into the air. Using 90% pure peroxide would have helped too.

As it is for jet packs, so it is with industrial chemistry. Bulk chemical processes can rarely be left to their own devices, as some reactions proceed so slowly that they’d be commercially infeasible. Catalysts are the key to the chemistry we need to keep the world running, and reactors full of them are a major feature of many of the processes of Big Chemistry.

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A Little Pigment Helps With Laser Glass Engraving

January 28, 2025 by 19 Comments

The range of materials suitable for even the cheapest laser cutter is part of what makes them such versatile and desirable tools. As long as you temper your expectations, there’s plenty of material to cut with your 40 watt CO2 laser or at least engrave—just not glass; that’s a tough one.

Or is it? According to [rschoenm], all it takes to engrave glass is a special coating. The recipe is easy: two parts white PVA glue, one part water, and two parts powdered titanium dioxide. The TiO2 is the important part; it changes color when heated by the laser, forming a deep black line that adheres to the surface of the glass. The glue is just there as a binder to keep the TiO2 from being blasted away by the air assist, and the water thins out the goop for easy spreading with a paintbrush. Apply one or two coats, let it dry, and blast away. Vector files work better than raster files, and you’ll probably have to play with settings to get optimal results.

With plain float glass, [rschoenm] gets really nice results. He also tried ceramic tile and achieved similar results, although he says he had to add a drop or two of food coloring to the coating so he could see it against the white tile surface. Acrylic didn’t work, but there are other methods to do that.

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Hackaday Links: January 26, 2025

January 26, 2025 by 7 Comments

Disappointing news this week for those longing for same-hour Amazon delivery as the retail giant tapped the brakes on its Prime Air drone deliveries. The pause is partially blamed on a December incident at the company’s Pendleton, Oregon test facility, where two MK30 delivery drones collided in midair during light rain conditions. A Bloomberg report states that the crash, which resulted in one of the drones catching fire on the ground, was due to a software error related to the weather. As a result, they decided to ground their entire fleet, which provides 60-minute delivery to test markets in Arizona and Texas, until a software update can be issued.

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Laser-Cut Metal Endoskeleton Beefs Up 3D Prints

January 24, 2025 by 23 Comments

There are limits to what you can do with an FDM printer to make your parts stronger. It really comes down to adding more plastic, like increasing wall thickness or boosting up the infill percentage. Other than that, redesigning the part to put more material where the part is most likely to fail is about the only other thing you can do. Unless, of course, you have access to a fiber laser cutter that can make internal metal supports for your prints.

As [Paul] explains it, this project stemmed from an unfortunate episode where a printed monitor stand failed, sending the LCD panel to its doom. He had taken care to reinforce that part by filling it with fiberglass resin, but to no avail. Unwilling to risk a repeat with a new tablet holder, he decided to test several alternative methods for reinforcing parts. Using a 100 W fiber laser cutter, he cut different internal supports from 0.2 mm steel shim stock. In one case he simply sandwiched the support between two half-thickness brackets, while in another he embedded the steel right into the print. He also made two parts that were filled with epoxy resin, one with a steel support embedded and one without.

The test setup was very simple, just a crane scale to measure the force exerted by pulling down on the part with his foot; crude, but effective. Every reinforced part performed better than a plain printed part with no reinforcement, but the clear winner was the epoxy-filled part with a solid-metal insert. Honestly, we were surprised at how much benefit such a thin piece of metal offered, even when it was directly embedded into the print during a pause.

Not everyone has access to a fiber laser cutter, of course, so this method might not be for everyone. In that case, you might want to check out other ways to beef up your prints, including just splitting them in two.

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Mining And Refining: The Halogens

January 21, 2025 by 25 Comments

I was looking at the periodic table of the elements the other day, as one does, when my eye fell upon the right-hand side of the chart. Right next to the noble gases at the extreme edge of the table is a column of elements with similar and interesting properties: the halogens. Almost all of these reactive elements are pretty familiar, especially chlorine, which most of us eat by the gram every day in the form of table salt. As the neighborhoods of the periodic table go, Group 17 is pretty familiar territory.

But for some reason, one member of this group caught my attention: iodine. I realized I had no idea where we get iodine, which led to the realization that apart from chlorine, I really didn’t know where any of the halogens came from. And as usual, that meant I needed to dig in and learn a little bit about the mining and refining of the halogens. At least most of them; as interesting as they may be, we’ll be skipping the naturally occurring but rare and highly radioactive halogen astatine, as well as the synthetic halogen tennessine, which lives just below it in the group.

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