Categorizing Steel

August 18, 2024 by 24 Comments

In the movie Conan the Barbarian, we hear a great deal about “the riddle of steel.” We are never told exactly what that riddle is, but in modern times, it might be: What’s the difference between 4150 and 1020 steel? If you’ve been around a machine shop, you’ve probably heard the AISI/SAE numbers, but if you didn’t know what they mean, [Jason Lonon] can help. The video below covers what the grade numbers mean in detail.

The four digits are actually two separate two-digit numbers. Sometimes, there will be five digits, in which case it is a two-digit number followed by a three-digit number. The first two digits tell you the actual type of steel. For example, 10 is ordinary steel, while 41 is chromium molybdenum steel. The last two or three digits indicate how much carbon is in the steel. If that number is, say, 40, then the steel contains approximately 0.40% carbon.

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Retrotechtacular: Powerline Sagging And Stringing In The 1950s

August 17, 2024 by 13 Comments

While high-voltage transmission lines are probably the most visible components of the electrical grid, they’re certainly among the least appreciated. They go largely unnoticed by the general public — quick, name the power line closest to you right now — at least until a new one is proposed, causing the NIMBYs and BANANAs to come out in force. To add insult to injury, those who do notice the megastructures that make modern life possible rarely take a moment to appreciate the engineering that goes into stringing up hundreds of miles of cable and making sure it stays up.

Not so the Bonneville Power Administration, the New Deal-era federal agency formed to exploit the hydroelectric abundance of the Pacific Northwest of the United States, which produced this 1950 gem detailing the stringing and sagging of power lines. Unsurprisingly, the many projects needed to wire together the often remote dams to the widely distributed population centers in an area that was only just starting to see growth began in the BPA’s offices, where teams of engineers hunched over desks worked out the best routes. Paper, pencil, and slide rules were the tools of the trade, along with an interesting gadget called a conductor sag template, a hardware implementation of the catenary equation that allowed the “sagger” to determine the height of each tower. The conductors, either steel-cored aluminum or pure copper, were also meticulously selected based on tensile strength, expected wind and ice loading, and the electrical load the line was expected to carry.

Once the engineers had their say, the hard work of physically stringing the wires began out in the field. One suspects that the work today is much the same as it was almost eighty years ago, save for much more stringent health and safety regulations. The prowess needed to transfer the wires from lifting sheaves to the insulators is something to behold, and the courage required to work from ladders hanging from wires at certain death heights is something to behold. But to our mind, the real heroes were the logistics fellows, who determined how much wire was needed for each span and exactly where to stage the reels. It’s worth sparing a moment’s thought for the daring photographer who captured all this action, likely with little more than a leather belt and hemp rope for safety.

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Spy Tech: Making Microdots

August 17, 2024 by 17 Comments

It isn’t just a spy movie trope: secret messages often show up as microdots. [The Thought Emporium] explores the history of microdots and even made a few, which turned out to be — to quote the video you can see below — “both easier than you might think, and yet also harder in other ways.”

If you want to hide a secret message, you really have two problems. The first is actually encoding the message so only the recipient can read it. However, in many cases, you also want the existence of the message to be secret. After all, if an enemy spy sees you with a folder of encrypted documents, your cover is blown even if they don’t know what the documents say.

Today, steganography techniques let you hide messages in innocent-looking images or data files. However, for many years, microdots were the gold standard for hiding secret messages and clandestine photographs. The microdots are typically no bigger than a millimeter to make them easy to hide in plain sight.

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40,000 FPS Omega camera captures Olympic photo-finish

Olympic Sprint Decided By 40,000 FPS Photo Finish

August 17, 2024 by 55 Comments

Advanced technology played a crucial role in determining the winner of the men’s 100-meter final at the Paris 2024 Olympics. In a historically close race, American sprinter Noah Lyles narrowly edged out Jamaica’s Kishane Thompson by just five-thousandths of a second. The final decision relied on an image captured by an Omega photo finish camera that shoots an astonishing 40,000 frames per second.

This cutting-edge technology, originally reported by PetaPixel, ensured the accuracy of the result in a race where both athletes recorded a time of 9.78 seconds. If SmartThings’ shot pourer from the 2012 Olympics were still around, it could once again fulfill its intended role of celebrating US medals.

Omega, the Olympics’ official timekeeper for decades, has continually innovated to enhance performance measurement. The Omega Scan ‘O’ Vision Ultimate, the camera used for this photo finish, is a significant upgrade from its 10,000 frames per second predecessor. The new system captures four times as many frames per second and offers higher resolution, providing a detailed view of the moment each runner’s torso touches the finish line. This level of detail was crucial in determining that Lyles’ torso touched the line first, securing his gold medal.

This camera is part of Omega’s broader technological advancements for the Paris 2024 Olympics, which include advanced Computer Vision systems utilizing AI and high-definition cameras to track athletes in real-time. For a closer look at how technology decided this historic race, watch the video by Eurosport that captured the event.

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A small physical version of the game 2048, played with LEDs as numbers and tilt for input.

2024 Tiny Games Challenge: It’s 2048, But With LEDs

August 17, 2024 by 8 Comments

Remember the game 2048? You slide numbered tiles around on a grid, combining them until you have one tile with a value of 2048 (although it’s possible to go higher). Legend has it that 2048 was created by a bored teenager in the space of a weekend to see if he could program a game from scratch.

It only took a couple of weekends for [David] to get Tiny2048 up and running. In this version, each RGB value represents a number value, and input comes from a rudimentary gesture detector — tilt it this way and that to move the LEDs and combine the ‘numbers’. As you might imagine, it was a bit tricky to use colors to represent numbers, so each one had to be sufficiently unique.

[David] says that the LED matrix is a string of WS2812 LEDs in a grid formation, controlled by an ESP32-S3-MINI-1. Although this may be overkill, [David] broke out a bunch of IO at the top of the board so it can be used in the future as a dev board. Be sure to check it out in blinkenlight action after the break!

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Roll Your Own Presence Sensor

August 16, 2024 by 7 Comments

[Mellow_Labs] wanted an Everything Presence Lite but found it was always out of stock. Therefore, he decided to create his own. The kit uses a millimeter wave sensor as a super-sensitive motion tracker for up to three people. It can even read your heart rate remotely. You can see a video of the project below.

There are a few differences from the original kit. Both use the C4001 24 GHz human presence detection sensor. However, the homebrew version also includes a BME680 environmental sensor.

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Fighting The Scourge Of “Screwdriver Mange”

August 16, 2024 by 45 Comments

We’ve all got our favorite hand tools, and while the selection criteria are usually pretty subjective, it usually boils down to a combination of looks and feel. In our opinion, the king of both these categories when it comes to screwdrivers is those clear, hard acetate plastic handles, which are a joy to use — at least until the plastic starts to degrade and exude a characteristically funky aroma.

But perhaps we can change that if these experiments on screwdriver “mange” hold up. That’s [357magdad]’s unappealing but accurate description of the chemical changes that eventually occur in the strong, hard, crystal-clear handles of your favorite screwdrivers. The polymer used for these handles is cellulose acetate butyrate, or CAB, which is mostly the same cellulose acetate that replaced the more explode-y cellulose nitrate in things like pool balls and movie film, except with some of the acetate groups replaced with a little butyric acid. The polymer is fine at first, but add a little UV light and over time the outer layer of CAB decomposes into a white flaky cellulose residue while the butyric acid volatilizes, creating the characteristic odor of vomitus. Lovely.

In the video below, [357magdad] takes a look at different concoctions that all allegedly cure the mange. TL, DW; it was a dunk in household ammonia that performed the best, well ahead of other common agents like vinegar and bleach. The ammonia — or more precisely, ammonium hydroxide — works very quickly on the cellulose residue, dissolving it readily and leaving the handle mange-free and looking nearly new after some light scrubbing. None of the other agents came close, although acetone did manage to clear up the mange a bit, at the cost of softening the underlying CAB in a process that’s probably similar to acetone smoothing ABS prints.

As for the funky smell, well, the results were less encouraging. Nothing really got rid of the pukey smell, even a roll in baking soda. We suspect there won’t be much for that, since humans can detect it down to 10 parts per million. Consider it the price to pay for a nice-looking screwdriver that feels so good in your hand. Continue reading “Fighting The Scourge Of “Screwdriver Mange”” →