Nuclear fission is a powerful phenomenon. When the conditions are right, atomic nuclei split, releasing neutrons that then split other nuclei in an ongoing chain reaction that releases enormous amounts of energy. This is how nuclear weapons work. In a more stable and controlled fashion, it’s how our nuclear reactors work too.
However, these chain reactions can also happen accidentally—with terrifying results. Though rare, criticality incidents – events where an accidental self-sustaining nuclear chain reaction occurs – serve as sobering reminders of the immense and unwieldy forces we attempt to harness when playing with nuclear materials.
The process of ironmaking has relied for centuries on iron ore, an impure form of iron oxide, slowly being reduced to iron by carbon monoxide in a furnace. Whether that furnace is the charcoal fire of an Iron Age craftsman or a modern blast furnace, the fundamental process remains the same, even if the technology around it has been refined. Now details are emerging of a new take on iron smelting from China, which turns what has always been a slow and intensive process into one that only takes a few seconds. So-called flash ironmaking relies on the injection of a fine iron ore powder into a superheated furnace, with the reduction happening explosively and delivering a constant stream of molten iron.
Frustratingly there is little detail on how it works, with the primary source for the news coverage being a paywalled South China Morning Post article. The journal article alluded to has proved frustratingly difficult to find online, leaving us with a few questions as to how it all works. Is the reducing agent still carbon monoxide, for example, or do they use another one such as hydrogen? The interesting part from an economic perspective is that it’s said to work on lower-grade ores, opening up the prospect for the Chinese steelmakers relying less on imports. There’s no work though on how the process would deal with the inevitable slag such ore would create.
If any readers have journal access we’d be interested in some insight in the comments, and we’re sure this story will deliver fresh information over time. Having been part of building a blast furnace of our own in the past, it’s something we find interesting
[Happy Little Diodes] built a Pi Pico logic analyzer designed by [El Dr. Gusman] using the original design. But he recently had a chance to test the newest version of the design, which is a big upgrade. You can see his take on the new design in the video below.
The original design could sample 24 channels at 100 MHz and required two different PCBs. The new version uses a single board and can operate up to 400 MHz. There’s also a provision for chaining multiple boards together to get more channels. You can set the level shifters to use 5 V, 3.3 V, or an external voltage. Since [Happy] is working on a ZX Spectrum, the 5 V conversion is a necessity.
The code is on GitHub, although it warns you that version six — the one seen in the video — isn’t stable, so you might have to wait to make one on your own. The software looks impressive and there may be some effort to integrate with Sigrok.
If you missed our coverage of the earlier version, you can still catch up. Dead set on Sigrok support? [Pico-Coder] can help you out.
London, Ontario college student [Victoria Korhonen] has captured the attention of tech enthusiasts and miniaturization lovers with her creation of what might be the world’s smallest arcade machine. Standing just 64 mm tall, 26 mm wide, and 30 mm deep, this machine is a scaled-down marvel playing the classic Atari game PONG. While the record isn’t yet official—it takes about three months for Guinness to certify—it’s clear [Korhonen]’s creation embodies ingenuity and dedication.
[Korhonen], an electromechanical engineering student, took six months to design and build this micro arcade. Inspired by records within reach, she aimed to outdo the previous tiniest arcade machine by shaving off just a few millimeters During the project she faced repeated failures, but viewed each iteration as a step towards success. Her miniature machine isn’t just a gimmick; it’s fully functional, with every component—from paddle mechanics to coding—developed from scratch.
[Korhonen] is already eyeing new projects, including creating the smallest humanoid robot. She also plans to integrate her electromechanical expertise into her family’s escape room business. Her journey aligns with other hobbyist projects pushing the limits of miniaturization, such as this credit card-sized Tetris clone or [Aliaksei Zholner]’s paper micro engines.
Hobbyist 3D printers have traditionally run the open source Marlin and later Klipper firmware, but as some hobbyists push their printers to the limits, more capable and less conservative firmware was needed. This is why the aptly named ‘Danger-Klipper’ fork of the Klipper firmware comes with the motto ‘I should be able to light my printer on fire’. Because the goal of Danger-Klipper wasn’t literally to light printers on fire (barring unfortunate accidents), the project has now been renamed to Kalico by the developers, after the pirate Calico Jack to maintain the nautical theming.
The Kalico project logo.
Not only does the project get a new name, but also a cute new pirate-themed calico cat logo. Beyond these changes not much else is different, though the documentation is obviously now also at a new domain. As a Klipper fork just about any printer that can run Klipper should be able to run Kalico, though the focus is on Raspberry Pi 2, 3 or 4. The FAQ has some more details on what Kalico can run on. Obviously, Kalico makes for a great option if you are building your own customized 3D printer (or similar), and will support the typical web UIs like Fluidd, OctoPrint, etc.
For some of the differences between Klipper and Kalico, the ‘Danger Features’ section of the documentation provides an impression. Suffice it to say that Kalico is not the kind of firmware to hold your hand or provide guiderails, making it an option for advanced users for whom breaking things while pushing boundaries is just part of the hobby.
For better or worse, a lot of human technology is confined to fewer dimensions than the three we can theoretically move about in. Cars and trains only travel two dimensionally with limited exceptions, maps and books generally don’t take advantage of a third dimension, and most computer displays and even the chips that make them work are largely two-dimensional in nature. Most styles of cooking can only apply heat in a single dimension as well, but [Dane Kouttron] wanted to make sure the meat his cookouts took advantage of a truly three-dimensional cooking style by adding a gyroscopic mechanism to the spit.
The first thing that needed to be built were a series of concentric rings for each of the three axes of rotation. Metal tubes were shaped with a pipe bender and then welded into their final forms, with an annealing step to flatten the loops. From there, the rings are attached to each other with a series of offset bearings. The outer tube is mounted above the fire and a single motor spins this tube. Since no piece of meat is perfectly symmetrical (and could be offset on the interior ring a bit even if it were) enough chaos is introduced to the system that the meat is free to rotate in any direction, change direction at any time, and overall get cooked in a more uniform way than a traditional single-dimensional rotating spit.
The cable car system of San Francisco is the last manually operated cable car system in the world, with three of the original twenty-three lines still operating today. With these systems being installed between 1873 and 1890, they were due major maintenance and upgrades by the time the 1980s and with it their 100th year of operation rolled around. This rebuilding and upgrading process was recorded in a documentary by a local SF television station, which makes for some fascinating viewing.
San Francisco cable car making its way through traffic. Early 20th century.
While the cars themselves were fairly straight-forward to restore, and the original grips that’d latch onto the cable didn’t need any changes. But there were upgrades to the lubrication used (originally pine tar), and the powerhouse (the ‘barn’) was completely gutted and rebuilt.
As opposed to a funicular system where the cars are permanently attached to the cable, a cable car system features a constantly moving cable that the cars can grip onto at will, with most of the wear and tear on the grip dies. Despite researchers at San Francisco State University (SFSU) investigating alternatives, the original metal grip dies were left in place, despite their 4-day replacement schedule.
Ultimately, the rails and related guides were all ripped out and replaced with new ones, with the rails thermite-welded in place, and the cars largely rebuilt from scratch. Although new technologies were used where available, the goal was to keep the look as close as possible to what it looked at the dawn of the 20th century. While more expensive than demolishing and scrapping the original buildings and rolling stock, this helped to keep the look that has made it a historical symbol when the upgraded system rolled back into action on June 21, 1984.
Decades later, this rebuilt cable car system is still running as smoothly as ever, thanks to these efforts. Although SF’s cable car system is reportedly mostly used by tourists, the technology has seen somewhat of a resurgence. Amidst a number of funicular systems, a true new cable car system can be found in the form of e.g. the MiniMetro system which fills the automated people mover niche.
