A Field Guide To The North American Cold Chain

July 17, 2025 by 20 Comments

So far in the “Field Guide” series, we’ve mainly looked at critical infrastructure systems that, while often blending into the scenery, are easily observable once you know where to look. From the substations, transmission lines, and local distribution systems that make up the electrical grid to cell towers and even weigh stations, most of what we’ve covered so far are mega-scale engineering projects that are critical to modern life, each of which you can get a good look at while you’re tooling down the road in a car.

This time around, though, we’re going to switch things up a bit and discuss a less-obvious but vitally important infrastructure system: the cold chain. While you might never have heard the term, you’ve certainly seen most of the major components at one time or another, and if you’ve ever enjoyed fresh fruit in the dead of winter or microwaved a frozen burrito for dinner, you’ve taken advantage of a globe-spanning system that makes sure environmentally sensitive products can be safely stored and transported.

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This Service Life Study Really Grinds Our Gears

July 17, 2025 by 57 Comments

3D printing is arguably over-used in the maker community. It’s just so easy to run off a quick prototype and then… well, it’s good enough, right? Choosing the right plastic can go a long way to making sure your “good enough” prototype really is good enough for long term use. If you’re producing anything with gearing, you might want to cast your eyes to a study by [Mert Safak Tunalioglu] and [Bekir Volkan Agca] titled: Wear and Service Life of 3-D Printed Polymeric Gears.

Photograph of the test rig used in the study.
No spin doctoring here, spinning gears.

The authors printed simple test gears in ABS, PLA, and PETG, and built a test rig to run them at 900 rpm with a load of 1.5 Nm against a steel drive gear. The gears were pulled off and weighed every 10,000 rotations, and allowed to run to destruction, which occurred in the hundreds-of-thousands of rotations in each case. The verdict? Well, as you can tell from the image, it’s to use PETG.

The authors think that this is down to PETG’s ductility, so we would have liked to see a hard TPU added to the mix, to say nothing of the engineering filaments. On the other hand, this study was aimed at the most common plastics in the 3D printing world and also verified a theoretical model that can be applied to other polymers.

This tip was sent in by [Benjamin], who came across it as part of the research to build his first telescope, which we look forward to seeing. As he points out, it’s quite lucky for the rest of us that the U.S. government provides funding to make such basic research available, in a way his nation of France does not. All politics aside, we’re grateful both to receive your tips and for the generosity of the US taxpayer.

We’ve seen similar tests done by the community — like this one using worm gears — but it’s also neat to see how institutional science approaches the same problem. If you need oodles of cycles but not a lot of torque, maybe skip the spurs and print a magnetic gearbox. Alternatively you break out the grog and the sea shanties and print yourself a capstan.

An image of a light grey graphing calculator with a dark grey screen and key surround. The text on the monochrome LCD screen shows "Input: ENEB Result 1: BEEN Confidence 1: 14% [##] Result 2: Good Confidence 2: 12% [#] Press ENTER key..."

A Neural Net For A Graphing Calculator?

July 17, 2025 by 1 Comment

Machine learning and neural nets can be pretty handy, and people continue to push the envelope of what they can do both in high end server farms as well as slower systems. At the extreme end of the spectrum is [ExploratoryStudios]’s Hermes Optimus Neural Net for a TI-84 Plus Silver Edition.

This neural net is setup as an autocorrect system that can take four character inputs and match them to a library of twelve words. That’s not a lot, but we’re talking about a device with 24 kB of RAM, so the little machine is doing its best. Perhaps more interesting than any practical output is the puzzle solving involved in getting this to work within the memory constraints.

The neural net “employs a feedforward neural network with a precisely calibrated 4-60-12 architecture and sigmoid activation functions.” This leads to an approximate 85% accuracy being able to identify and correct the given target words. We appreciate the readout of the net’s confidence as well which is something that seems to have gone out the window with many newer “AI” systems.

We’ve seen another TI-84 neural net for handwriting recognition, but is the current crop of AI still headed in the wrong direction?

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Vintage Hardware Find Includes Time Capsule Of Data

July 16, 2025 by 4 Comments

Before social media brought the Internet to the masses, and before even Napster, ICQ, and AIM gave those with a phone line a reason to connect online at all, those who went online often went to a BBS messageboard. By modern standards these text-only environments would have been extremely limited, with only weather updates, stock information, limited news, some email and messaging, and perhaps some classifieds or other miscellaneous information. This was an important time for the early Internet though, and [Nicola] recently discovered a time capsule of sorts from this era.

He first got a tip about a piece of vintage hardware, a DEC VAXstation II which was missing from his collection. But after painstakingly preserving the data on the hard drive he found it had been hosting one of these BBS servers and had plenty of gems from the era to show off. Not only does this build restore the DEC hardware but [Nicola] was able to virtualize the server using the data he recovered on a SIMH emulator, granting insights into how the Internet of this era was used.

[Nicola] also brought the BBS messaging system back online, although he notes that running it on the original hardware wouldn’t be feasible so for now it runs in the cloud. It’s a fascinating look into the Internet of the past, far beyond when many of us first went online as well. For a deep dive on how these systems worked, as well as an introduction to some of the Internet culture of the day, we saw this guide to the BBS a little while ago.

This SSD Will Self Destruct In Ten Seconds…

July 16, 2025 by 16 Comments

In case you can’t wait for your flash memory to die from write cycling, TeamGroup now has a drive that, via software or hardware, can destroy its own flash chips with a surge of voltage. If you wonder why you might want this, there are military applications where how you destroy a piece of equipment is right up there in the manual with how to use it.

They have obviously put a lot of thought into it, as you can see in the video below. Apparently, if you are in the middle of blowing up the flash and power cuts out, the chip will resume frying itself when you restore power.

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Opening A Six-Lock Safe With One Key Using Brunnian Links

July 16, 2025 by 6 Comments

Brunnian links are a type of nontrivial link – or knot – where multiple linked loops become unlinked if a single loop is cut or removed. Beyond ‘fun’ disentanglement toys and a tantalizing subject of academic papers on knot theory, it can also be used for practical applications, as demonstrated by [Anthony Francis-Jones] in a recent video. In it we get a safe that is locked with multiple padlocks, each of which can unlock and open the safe by itself.

This type of locked enclosure is quite commonly used in military and other applications where you do not want to give the same key to each person in a group, yet still want to give each person full access. After taking us through the basics of Brunnian links, including Borromean rings, we are introduced to the design behind the safe with its six padlocks.

As a demonstration piece it uses cheap luggage padlocks and Perspex (acrylic) rods and sheets to give a vibrant and transparent view of its workings. During the assembly it becomes quite apparent how it works, with each padlock controlling one direction of motion of a piece, each of which can be used to disassemble the entire locking mechanism and open the safe.

Brunnian links are also found in the braids often made by children out of elastic bands, which together with this safe can be used to get children hooked on Brunnian links and general knot theory.

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Mini Car Racing Game Really Shows Off Multicolor Printing

July 16, 2025 by 12 Comments

Quality 3D printing is a common hobbyist tool nowadays, and [wontonnn]’s mini arcade car racing game really shows off how 3D printing can bring parts from functional to fantastic. There are quite a few details we like in [wontonn]’s design, so let’s take a closer look.

The mini mechanical game is one of those treadmill-based car racing games in which the player navigates a little car between an onslaught of belt-borne obstacles. A little DC motor spins things up in a modular side assembly, and a hand-cranked option is available. The player’s car attaches via a magnet to a steering arm; if the player’s car gets knocked off the magnet, game over.

Treadmill belt segments print as large pre-assembled pieces, with ends that snap together without connectors. Belts like this are sometimes tricky, so this is worth keeping in mind should one ever need a similar part. Since there are no external fasteners or hardware to depend on, one could resize it easily to suit their own project purposes.

The finishing touches on the whole assembly look great. It used to be that the sort of colors and lettering seen here would come from a sticker or label, but [wontonn] gets clean lines and colors by raising (or sinking) different parts of the design. The checkerboard pattern, for example, has the light squares raised for printing in a different color.

Electromechanical arcade games have an appeal all their own, being a fusion of both mechanical and electric design that comes together in a special way. Want to make your own? Get inspired by the classic Lunar Lander reimagined, or check out this LEGO treadmill racer that takes an entirely different approach to the concept.

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