Why Can’t I 3D Print With Rubber?

December 31, 2025 by Jenny List 59 Comments

A friend of mine and I both have a similar project in mind, the manufacture of custom footwear with our hackerspace’s shiny new multi-material 3D printer. It seems like a match made in heaven, a machine that can seamlessly integrate components made with widely differing materials into a complex three-dimensional structure. As is so often the case though, there are limits to what can be done with the tool in hand, and here I’ve met one of them.

I can’t get a good range of footwear for my significantly oversized feet, and I want a set of extra grippy soles for a particular sporting application. For that the best material is a rubber, yet the types of rubber that are best for the job can unfortunately not be 3D printed. In understanding why that is the case I’ve followed a fascinating path which has taught me stuff about 3D printing that I certainly didn’t know.

The extruder unit from a Prusa Mini 3D printer — Newton strikes back, and I can’t force rubber through this thing.

A friend of mine from way back is a petrochemist, so I asked him about the melting points of various rubbers to see if I could find an appropriate filament His answer, predictably, was that it’s not that simple, because rubbers don’t behave in the same way as the polymers I am used to. With a conventional 3D printer filament, as the polymer is fed into the extruder and heated up, it turns to liquid and flows out of the nozzle to the print. It ‘s then hot enough to fuse with the layer below as it solidifies, which is how our 3D prints retain their shape. This property is where we get the term “plastic” from, which loosely means “Able to be moulded”.

My problem is that rubber doesn’t behave that way. As any casual glance at a motor vehicle will tell you, rubber can be moulded, but it doesn’t neatly liquefy and flow in the way my PLA or PET does. It’s a non-Newtonian fluid, a term which I was familiar with from such things as non-drip paint, tomato ketchup, or oobleck, but had never as an electronic engineer directly encountered in something I am working on. Continue reading “Why Can’t I 3D Print With Rubber?” →

How Wind Nearly Took Down Boulder NTP

December 29, 2025 by Fenix Guthrie 28 Comments

NTP is one of the most interesting and important, but all too forgotten, protocols that makes the internet tick. Accurate clock synchronization is required for everything ranging from cryptography to business and science. NTP is closely tied around a handful of atomic clocks, some in orbit on GPS satellites, and some in laboratories. So the near-failure of one such atomic clock sparked a rather large, and nerdy, internet debate.

On December 17, 2025, the Colorado front range experience a massive wind storm. The National Center for Atmospheric Reassure in Boulder recorded gusts in excess of 100 mph (about 85 knots or 160 kph). This storm was a real doozy, but gusts this strong are not unheard of in Boulder either. That is no small reason the National Renewable Energy Laboratory (now the National Laboratory of the Rockies) has a wind turbine testing facility in the neighborhood.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Ultimate Portable Split

December 23, 2025 by Kristina Panos 8 Comments

What do you look for in a travel keyboard? For me, it has to be split, though this condition most immediately demands a carrying solution of some kind. Wirelessness I can take or leave, so it’s nice to have both options available. And of course, bonus points if it looks so good that people interrupt me to ask questions.

A pair of hands poised above a blue split keyboard that packs easily for travel in a 3D-printed case. The case doubles as a laptop stand. — Image by [kleshwong] via YouTube

Depending on your own personal answers to this burning question, the PSKEEB 5 just may be your endgame. And, lucky for you, [kleshwong] plans to open source it soon. All he asks for is your support by watching the video below and doing the usual YouTube-related things.

You’ll see a couple of really neat features, like swing-out tenting feet, a trackpoint, rotary encoders, and the best part of all — a carrying case that doubles as a laptop stand. Sweet!

Eight years in the making, this is the fifth in a series, thus the name: the P stands for Portability; the S for Split. [kleshwong] believes that 36 keys is just right, as long as you have what you need on various layers.

So, do what you can in the like/share/subscribe realm so we can all see the GitHub come to pass, would you? Here’s the spot to watch, and you can enjoy looking through the previous versions while you wait with your forks and stars.

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Surviving The RAM Apocalypse With Software Optimizations

December 23, 2025 by Maya Posch 115 Comments

To the surprise of almost nobody, the unprecedented build-out of datacenters and the equipping of them with servers for so-called ‘AI’ has led to a massive shortage of certain components. With random access memory (RAM) being so far the most heavily affected and with storage in the form of HDDs and SSDs not far behind, this has led many to ask the question of how we will survive the coming months, years, decades, or however-long the current AI bubble will last.

One thing is already certain, and that is that we will have to make our current computer systems last longer, and forego simply tossing in more sticks of RAM in favor of doing more with less. This is easy to imagine for those of us who remember running a full-blown Windows desktop system on a sub-GHz x86 system with less than a GB of RAM, but might require some adjustment for everyone else.

In short, what can us software developers do differently to make a hundred MB of RAM stretch further, and make a GB of storage space look positively spacious again?

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Ask Hackaday: What Goes Into A Legible Font, And Why Does It Matter?

December 22, 2025 by Jenny List 72 Comments

Two patent front pages, on the left American with a serif font, on the right British with a sans serif font. — American and British patents, for comparison.

There’s an interesting cultural observation to be made as a writer based in Europe, that we like our sans-serif fonts, while our American friends seem to prefer a font with a serif. It’s something that was particularly noticeable in the days of print advertising, and it becomes very obvious when looking at government documents.

We’ve brought together two 1980s patents from the respective sources to illustrate this, the American RSA encryption patent, and the British drive circuitry patent for the Sinclair flat screen CRT. The American one uses Times New Roman, while the British one uses a sans-serif font which we’re guessing may be Arial. The odd thing is in both cases they exude formality and authority to their respective audiences, but Americans see the sans-serif font as less formal and Europeans see the serif version as old-fashioned. If you thought Brits and Americans were divided by a common language, evidently it runs much deeper than that. Continue reading “Ask Hackaday: What Goes Into A Legible Font, And Why Does It Matter?” →

Hackaday Links: December 21, 2025

December 21, 2025 by Dan Maloney 15 Comments

It’s amazing how fragile our digital lives can be, and how quickly they can fall to pieces. Case in point: the digital dilemma that Paris Buttfield-Addison found himself in last week, which denied him access to 20 years of photographs, messages, documents, and general access to the Apple ecosystem. According to Paris, the whole thing started when he tried to redeem a $500 Apple gift card in exchange for 6 TB of iCloud storage. The gift card purchase didn’t go through, and shortly thereafter, the account was locked, effectively bricking his $30,000 collection of iGadgets and rendering his massive trove of iCloud data inaccessible. Decades of loyalty to the Apple ecosystem, gone in a heartbeat.

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Bare Metal STM32: Increasing The System Clock And Running Dhrystone

December 18, 2025 by Maya Posch 9 Comments

When you start an STM32 MCU with its default configuration, its CPU will tick along at a leisurely number of cycles on the order of 8 to 16 MHz, using the high-speed internal (HSI) clock source as a safe default to bootstrap from. After this phase, we are free to go wild with the system clock, as well as the various clock sources that are available beyond the HSI.

Increasing the system clock doesn’t just affect the CPU either, but also affects the MCU’s internal buses via its prescalers and with it the peripherals like timers on that bus. Hence it’s essential to understand the clock fabric of the target MCU. This article will focus on the general case of increasing the system clock on an STM32F103 MCU from the default to the maximum rated clock speed using the relevant registers, taking into account aspects like Flash wait states and the APB and AHB prescalers.

Although the Dhrystone benchmark is rather old-fashioned now, it’ll be used to demonstrate the difference that a faster CPU makes, as well as how complex accurately benchmarking is. Plus it’s just interesting to get an idea of how a lowly Cortex-M3 based MCU compares to a once top-of-the line Intel Pentium 90 CPU.

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