3D Printed TPU Bellows With PLA Interface Layers

Of all FDM filament types, flexible ones such as TPU invite a whole new way of thinking, as well as applications. Case in point the TPU-based bellows that the [Functional Part Friday] channel on YouTube recently demonstrated.

The idea is quite straightforward: you print TPU and PLA in alternating layers, making sure that the TPU is connected to its previous layer in an alternating fashion. After printing, you peel the PLA and TPU apart, remove the PLA layers and presto, you got yourself bellows.

There were some issues along the way, of course. Case in point the differences between TPU from different brands (Sainsmart, Sunlu) that caused some headaches, and most of all the incompatibility between the Bambu Lab AMS and TPU that led to incredibly brittle TPU prints. This required bypassing the feed mechanism in the AMS, which subsequently went down a rabbit hole of preventing the PTFE tube from getting sucked into the AMS. Being able to print TPU & PLA at the same time also requires a printer with two independent extruders like the Bambu Lab H2D used here, as both materials do not mix in any way. Great news for H2D and IDEX printer owners, of course.

As for practical applications for bellows, beyond printing your own 1900s-era camera, accordion or hand air bellows, you can also create lathe way covers and so on.

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Jellybean Mac Hides Modern PC

The iMac G3 is an absolute icon of industrial design, as (or perhaps more) era-defining than the Mac Classic before it. In the modern day, if your old iMac even boots, well, you can’t do much with it. [Rick Norcross] got a hold of a dead (hopefully irreparable) specimen, and stuffed a modern PC inside of it.

From the outside, it’s suprizingly hard to tell. Of course the CRT had to go, replaced with a 15″ ELO panel that fits well after being de-bezeled. (If its resolution is only 1024 x 768, well, it’s also only 15″, and that pixel density matches the case.) An M-ATX motherboard squeezes right in, above a modular PSU. Cooling comes from a 140 mm case fan placed under the original handle. Of course you can’t have an old Mac without a startup chime, and [Rick] obliges by including an Adafruit FX board wired to the internal speakers, set to chime on power-up while the PC components are booting.

These sorts of mods have proven controversial in the past– certainly there’s good reason to want to preserve aging hardware–but perhaps with this generation of iMac it won’t raise the same ire as when someone guts a Mac Classic. We’ve seen the same treatment given to a G4 iMac, but somehow the lamp doesn’t quite have the same place in our hearts as the redoubtable jellybean.

Superconductivity News: What Makes Floquet Majorana Fermions Special For Quantum Computing?

Researchers from the USA and India have proposed that Floquet Majorana fermions may improve quantum computing by controlling superconducting currents, potentially reducing errors and increasing stability.

In a study published in Physical Review Letters that was co-authored by [Babak Seradjeh], a Professor of Physics at Indiana University Bloomington, and theoretical physicists [Rekha Kumari] and [Arijit Kundu], from the Indian Institute of Technology Kanpur, the scientists validate their theory using numerical simulations.

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Wireless USB Autopsy

It might seem strange to people like us, but normal people hate wires. Really hate wires. A lot. So it makes sense that with so many wireless technologies, there should be a way to do USB over wireless. There is, but it really hasn’t caught on outside of a few small pockets. [Cameron Kaiser] wants to share why he thinks the technology never went anywhere.

Wireless USB makes sense. We have high-speed wireless networking. Bluetooth doesn’t handle that kind of speed, but forms a workable wireless network. In the background, of course, would be competing standards.

Texas Instruments and Intel wanted to use multiband orthogonal frequency-division multiplexing (MB-OFDM) to carry data using a large number of subcarriers. Motorola (later Freescale), HP, and others were backing the competing direct sequence ultra-wideband or DS-UWB. Attempts to come up with a common system degenerated.

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Liquid Silicone 3D Printing Is No Joke

They might call it Levity, but there’s nothing funny about Rapid Liquid Print’s new silicone 3D printer. It has to be seen to be believed, and luckily [3D Printing Nerd] gives us lots of beauty shots in this short video, embedded below.

Smooth, and fast. This bladder took 51 minutes according to the RLP website.

Printing a liquid, even a somewhat-viscous one like platinum-cure silicone, presents certain obvious challenges. The Levity solves them with buoyancy: the prints are deposited not onto a bed, but into a gel, meaning they are fully supported as the silicone cures. The fact that the liquid doesn’t cure instantly has a side benefit: the layers bleed into one another, which means this technique should (in theory) be stronger in all directions than FDM printing. We have no data to back that up, but what you can see for yourself that the layer-blending creates a very smooth appearance in the finished prints.

If you watch the video, it really looks like magic, the way prints appear in the gel. The gel is apparently a commercially-available hydrogel, which is good since the build volume looks to need  ̶a̶b̶o̶u̶t̶ ̶5̶0̶0̶ ̶L̶ at least 125 L of the stuff. The two-part silicone is also industry-standard and off-the-shelf, though no doubt the exact ratios and are tweaked for purpose. There’s no magic, just a really neat technology.

If you want one, you can sign up for the waiting list at Rapid Liquid Print’s website, but be prepared to wait; units ship next year, and there’s already a list.

Alternatively, since there is no magic here, we’d love to see someone take it on themselves, the way once equally exotic SLS printers have entered the DIY world. There was a time when resin printers were new and exotic and hobbyists had to roll their own, too. None of this is to say we don’t respect the dickens out of the Rapid Liquid Print team and their achievement–it’s just that imitation is the sincerest form of flattery. Continue reading “Liquid Silicone 3D Printing Is No Joke”

FLOSS Weekly Episode 832: Give Yourself A Medal

This week, Jonathan Bennett chats with Alexandre Dulaunoy and Quentin Jérôme about Kunai and CIRCL! How does Kunai help solve Linux security monitoring? Why is eBPF the right place for one of these tools to run? And how is CIRCL helping Luxembourg and the world deal with the modern security landscape? Watch to find out!

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Cabinentaxi layout as it existed in 1978, with labels by the Tim Traveller YT channel.

Germany’s Cabinentaxi: The Double-Sided Monorail That Wasn’t Meant To Be

The 1970s was a perfect time for alternative modes of transport to be trialed that might replace cars in the wake of the global oil crisis. One of these was the Cabinentaxi, or C-Bahn as it was later called, which was a variation on the standard suspended and monorail concepts.

It was a people mover concept, with ‘pods’ (or cabins) that’d ride either on top of or below the suspended track. It was tested intensively over the course of six years, performed admirably, and completely failed to materialize commercially due to budget crunch times around the world.

Image of the Cabinentaxi from a promotional video, showing carriages on top and below the monorail.

Recently [Tim Traveller] went to the muddy farm field that once housed the big test track (pictured above), of which nothing remains but the gates and a sign. Despite the fact that few people have heard of Cabinentaxi prior to seeing [Tim]’s video or reading this, there is a big Wikipedia entry on it, as well as a (German language) site dedicated to the technology.

What made the C-Bahn different from trains and buses were the smaller pods, high throughput capacity and ability to call a pod on demand at any of the stations. This kind of flexibility is what is seen more or less with today’s people moving systems at airports and some cities, except the C-Bahn was classified as a personal rapid transport (PRT), with on-demand pods that could travel between any two stations without stopping or delays. This is something that isn’t seen with public transport today, even if self-driving cars purport to one day do this kind of trick.

Considering that this technology died most due to economical circumstances, we remain hopeful to see its revival one day.

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