If At First You Don’t Succeed…

… at least document what failed and give the failure analysis a good effort. And then later on, you can “try, try again” or let someone else carry on with the work; they’ll have a good basis to start from.

We were talking about a project to use 10 W blue lasers to post-smooth 3D prints when I came up with this not-very-catchy catchphrase. The project itself is very much “in progress”, which is a nice way of saying that it hasn’t yet fully met its goals. But nonetheless I was entirely happy to watch not one, but two, videos where [I changed a thing] discussed the intricacies of laser-smoothing 3D prints, precisely because it sounds easy but absolutely isn’t, and because the problems were laid out so well.

I definitely take for granted how easy the slice-it-into-layers nature of FDM 3D printers makes path planning. After all, you can print interlocking knots, hinges, and even entire sections of chain mail as long as you only have to go one layer at a time. When you print this way, you never have to worry about the print head crashing into something that you’ve printed before, or being unable to reach into a small valley. To smooth two or more layers of a 3D print into each other, you are suddenly out of the comfy flatland. You have to worry about collisions, obstructions, and all the rest of actual 3D.

But those issues and more were carefully documented as [I changed a thing] went through his attempts at writing the software to drive the laser-augmented machine, and honestly that attention to the problems that were confounding him was worth a dozen “success” videos. In that sense, it worked on me a little like nerd sniping.

Those were my takeaways from the video series, then. One, it’s hard to do laser smoothing uniformly. But two, documenting the difficulties, considerations, and failures for your future self, or for others, is not just good practice, but can also encourage other people to help you with your project, or to take it on themselves. The more thought you put into how and why your project failed, the more bait you’re laying out for the next nerd. And that’s at least one part of what makes the open-source ethos work.

Failed 3D Printed Part Brings Down Small Plane

Back in March, a small aircraft in the UK lost engine power while coming in for a landing and crashed. The aircraft was a total loss, but thankfully, the pilot suffered only minor injuries. According to the recently released report by the Air Accidents Investigation Branch, we now know a failed 3D printed part is to blame.

The part in question is a plastic air induction elbow — a curved duct that forms part of the engine’s air intake system. The collapsed part you see in the image above had an air filter attached to its front (towards the left in the image), which had detached and fallen off. Heat from the engine caused the part to soften and collapse, which in turn greatly reduced intake airflow, and therefore available power.

Serious injury was avoided, but the aircraft was destroyed.

While the cause of the incident is evident enough, there are still some unknowns regarding the part itself. The fact that it was 3D printed isn’t an issue. Additive manufacturing is used effectively in the aviation industry all the time, and it seems the owner of the aircraft purchased the part at an airshow in the USA with no reason to believe anything was awry. So what happened?

The part in question is normally made from laminated fiberglass and epoxy, with a glass transition of 84° C. Glass transition is the temperature at which a material begins to soften, and is usually far below the material’s actual melting point.

When a part is heated at or beyond its glass transition, it doesn’t melt but is no longer “solid” in the normal sense, and may not even be able to support its own weight. It’s the reason some folks pack parts in powdered salt to support them before annealing.

The printed part the owner purchased and installed was understood to be made from CF-ABS, or ABS with carbon fiber. ABS has a glass transition of around 100° C, which should have been plenty for this application. However, the investigation tested two samples taken from the failed part and measured the glass temperature at 52.8°C and 54.0°C, respectively. That’s a far cry from what was expected, and led to part failure from the heat of the engine.

The actual composition of the part in question has not been confirmed, but it sure seems likely that whatever it was made from, it wasn’t ABS. The Light Aircraft Association (LAA) plans to circulate an alert to inspectors regarding 3D printed parts, and the possibility they aren’t made from what they claim to be.

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Hackaday Links: February 23, 2025

Ho-hum — another week, another high-profile bricking. In a move anyone could see coming, Humane has announced that their pricey AI Pin widgets will cease to work in any meaningful way as of noon on February 28. The company made a splash when it launched its wearable assistant in April of 2024, and from an engineering point of view, it was pretty cool. Meant to be worn on one’s shirt, it had a little bit of a Star Trek: The Next Generation comm badge vibe as the primary UI was accessed through tapping the front of the thing. It also had a display that projected information onto your hand, plus the usual array of sensors and cameras which no doubt provided a rich stream of user data. Somehow, though, Humane wasn’t able to make the numbers work out, and as a result they’ll be shutting down their servers at the end of the month, with refunds offered only to users who bought their AI Pins in the last 90 days.

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Blame It On The Sockets: Forensic Analysis Of The Arecibo Collapse

Nearly three years after the rapid unplanned disassembly of the Arecibo radio telescope, we finally have a culprit in the collapse: bad sockets.

In case you somehow missed it, back in 2020 we started getting ominous reports that the cables supporting the 900-ton instrument platform above the 300-meter primary reflector of what was at the time the world’s largest radio telescope were slowly coming undone. From the first sign of problems in August, when the first broken cable smashed a hole in the reflector, to the failure of a second cable in November, it surely seemed like Arecibo’s days were numbered, and that it would fall victim to all the other bad luck we seemed to be rapidly accruing in that fateful year. The inevitable finally happened on December 1, when over-stressed cables on support tower four finally gave way, sending the platform on a graceful swing into the side of the natural depression that cradled the reflector, damaging the telescope beyond all hope of repair.

The long run-up to the telescope’s final act had a silver lining in that it provided engineers and scientists with a chance to carefully observe the failure in real-time. So there was no real mystery as to what happened, at least from a big-picture perspective. But one always wants to know the fine-scale details of such failures, a task which fell to forensic investigation firm Thornton Tomasetti. They enlisted the help of the Columbia University Strength of Materials lab, which sent pieces of the failed cable to the Oak Ridge National Laboratory’s High Flux Isotope reactor for neutron imaging, which is like an X-ray study but uses streams of neutrons that interact with the material’s nuclei rather than their electrons.

The full report (PDF) reveals five proximate causes for the collapse, chief of which is “[T]he manual and inconsistent splay of the wires during cable socketing,” which we take to mean that the individual strands of the cables were not spread out correctly before the molten zinc “spelter socket” was molded around them. The resulting shear stress caused the zinc to slowly flow around the cable strands, letting them slip out of the surrounding steel socket and — well, you can watch the rest below for yourself.

As is usually the case with such failures, there are multiple causes, all of which are covered in the 300+ page report. But being able to pin the bulk of the failure on a single, easily understood — and easily addressed — defect is comforting, in a way. It’s cold comfort to astronomers and Arecibo staff, perhaps, but at least it’s a lesson that might prevent future failures of cable-supported structures.

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Books You Should Read: Why Buildings Fall Down

People with long commutes usually come up with tricks to stay focused and alert and avoid the dangerous tendency to zone out during the drive. One trick I used to use was keeping mental track of the various construction projects I’d pass by on my way to work, noticing which piers on a new highway overpass were nearing completion, or watching steelworkers put together the complex rebar endoskeletons of a new stretch of roadway.

One project I loved to watch back in the 80s was a new high-rise going in right next to the highway, which fascinated me because of the construction method. Rather than putting together a steel frame, laying out decking, and covering each floor with concrete, the workers seemed to be fabricating each floor at ground level and then jacking them up on the vertical steel columns. I was fascinated by this because every time I passed by the floors were in a different position, spreading out vertically as the building grew.

And then one day, it just wasn’t there anymore. Where there had been columns stretching nine stories into the city sky with concrete slabs lined up ready to be jacked up into their final positions, there was just an enormous hole in the ground with a ghastly gray cloud of concrete dust rising from it. It was April 23, 1987, and what was once going to be a luxury apartment building called L’Ambience Plaza in Bridgeport, Connecticut lay pancaked into the ground, entombing the bodies of 28 construction workers.

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So How Does A Rocket Fly Sideways, Anyway?

It’s often said that getting into orbit is less about going up, and more about going sideways very fast. So in that sense, the recent launch conducted by aerospace startup Astra could be seen as the vehicle simply getting the order of operations wrong. Instead of going up and then burning towards the horizon, it made an exceptionally unusual sideways flight before finally moving skyward.

As you might expect, the booster didn’t make it to orbit. But not for lack of trying. In fact, that the 11.6 meter (38 feet) vehicle was able to navigate through its unprecedented lateral maneuver and largely correct its flight-path is a testament to the engineering prowess of the team at the Alameda, California based company. It’s worth noting that it was the ground controller’s decision to cut the rocket’s engines once it had flown high and far enough away to not endanger anyone on the ground that ultimately ended the flight; the booster itself was still fighting to reach space until the very last moment.

Astra’s rocket on the launch pad.

There’s a certain irony to the fact that this flight, the third Astra has attempted since their founding in 2016, was the first to be live streamed to YouTube. Had the company not pulled back their usual veil of secrecy, we likely wouldn’t have such glorious high-resolution footage of what will forever be remembered as one of the most bizarre rocket mishaps in history. The surreal image of the rocket smoothly sliding out of frame as if it was trying to avoid the camera’s gaze has already become a meme online, arguably reaching a larger and more diverse audience than would have resulted from a successful launch. As they say, there’s no such thing as bad press.

Naturally, the viral clip has spurred some questions. You don’t have to be a space expert to know that the pointy end of the rocket is usually supposed to go up, but considering how smooth the maneuver looks, some have even wondered if it wasn’t somehow intentional. With so much attention on this unusual event, it seems like the perfect time to take a close look at how Astra’s latest rocket launch went, quite literally, sideways.

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Sirius XM Satellite Failure A Reminder That Space Is Risky (And That Satellite Insurance Is A Thing)

It’s easy to imagine that once a spacecraft leaves Earth’s atmosphere and is in a stable orbit, the most dangerous phase of the mission is over. After all, that’s when we collectively close the live stream and turn our attentions back to terrestrial matters. Once the fire and fury of the launch is over with, all the excitement is done. From that point on, it’s just years of silently sailing through the vacuum of space. What’s the worst that could happen?

Unfortunately, satellite radio provider Sirius XM just received a harsh reminder that there’s still plenty that can go wrong after you’ve slipped Earth’s surly bonds. Despite a flawless launch in early December 2020 on a SpaceX Falcon 9 and a reportedly uneventful trip to its designated position in geostationary orbit approximately 35,786 km (22,236 mi) above the planet, their brand new SXM-7 broadcasting satellite appears to be in serious trouble.

Maxar Technologies, prime contractor for the SXM-7, says they’re currently trying to determine what’s gone wrong with the 7,000 kilogram satellite. In a statement, the Colorado-based aerospace company claimed they were focused on “safely completing the commissioning of the satellite and optimizing its performance.” But the language used by Sirius XM in their January 27th filing with the U.S. Securities and Exchange Commission was notably more pessimistic. No mention is made of bringing SXM-7 online, and instead, the company makes it clear that their existing fleet of satellites will be able to maintain service to their customers until a replacement can be launched.

So what happened, and more importantly, is there any hope for SXM-7? Neither company has released any concrete details, and given the amount of money on the line, there’s a good chance the public won’t get the full story for some time. But we can theorize a bit based on what we do know, and make some predictions about where things go from here.

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