#SGU #TheSkepticsGuideToTheUniverse:
The Skeptics Guide #1028 - Mar 22 2025

Interview with Michael Marshall @michaelmarshall6504 and Cecil #Cicirello; News Items: #NASA Delays #Artemis, Punishing #AI, Hybrid #Bionic_Hand, #Pettawatt #ElectronBeam; Who's That #Noisy; Your Questions and E-mails: Rewriting #Physics; #Science or Fiction

Webseite der Episode: https://www.theskepticsguide.org/podcast/sgu

Mediendatei: https://mgln.ai/e/35/traffic.libsyn.com/secure/skepticsguide/skepticast2025-03-22.mp3

Hackaday Links: April 10, 2022

A funny thing happened on the way to the delta. The one on Jezero crater on Mars, that is, as the Perseverance rover may have captured a glimpse of the parachute that helped deliver it to the Red Planet a little over a year ago. Getting the rover safely onto the Martian surface was an incredibly complex undertaking, made all the more impressive by the fact that it was completely autonomous. The parachute, which slowed the descent vehicle holding the rover, was jettisoned well before the "Sky Crane" deployed to lower the rover to the surface. The parachute wafted to the surface a bit over a kilometer from the landing zone. NASA hasn't confirmed that what's seen in the raw images is the chute; in fact, they haven't even acknowledged the big white thing that's obviously not a rock in the picture at all. Perhaps they're reserving final judgment until they get an overflight by the Ingenuity helicopter, which is currently landed not too far from where the descent stage crashed. We'd love to see pictures of that wreckage.

We recently had a Hack Chat on 3D printing metal where Agustin Cruz came on to talk about his attempt to build an affordable electron beam sintering printer. The chat was great, and now Agustin has made a bunch of progress that's worth a look. The idea behind electron beam sintering is simple -- it's basically a souped-up version of the electron gun and deflection coils in the back of a CRT, which blasts away at a bed of fine metal powder to sinter it together, layer by layer. The details, though, like working in a vacuum, precisely depositing a fresh layer of powder, and precisely controlling beam power and position, are non-trivial. Check out Agustin's progress on his Hackaday.io project.

Do you think of yourself as a boring person? Chances are you don't -- it seems like being a bore is like having bad breath, in that it's hard to tell if you've got it. But according to a new study, boring people are not only quantifiable, but the stereotypes about them are all pretty much true -- or at least consistent. The methodology seems a little subjective, though -- participants were asked to provide a brief description of a boring person, which hilariously included former US Vice President Al Gore for his "really monotone speech" and "no emotion." They then imagined personality characteristics, hobbies, and occupations for these stereotypical bores, coming up with things like long-winded stories, geocaching, and accounting. Feeling personally attacked by this point, we read no further, but the take-home message seems to be that while everyone is boring to someone, you really have to work at it to be boring to everyone.

If you listen to the Hackaday Podcast, which of course immediately disqualifies you from the boring people cohort, you'll know about the "What's That Sound?" segment, where a short clip of some tech-relevant sound is played, and if you can identify it, riches and fame await. Well, if you can't get enough of that stuff, head over to the Museum of Endangered Sounds, which seeks to preserve our auditory heritage before it slips away. The site has a mere smattering of sounds so far, including the AIM message alert, the old Nokia ringtone, Windows 95 startup, a floppy drive seeking tracks, and the sound of a cartridge being inserted into a Nintendo NES, complete with the obligatory blowing on the connector. We can think of literally thousands of more sounds worth preserving, and while we don't see a way to contribute sounds, it might be worth pinging the proprietor if you can think of anything.

And finally, I share with you the following photo, sent by my son, currently studying at the University of Idaho, snapped moments before his attempted abduction:

Thankfully, he managed to sidestep the slow-moving swarm and make good his escape. I count thirteen of these Starship delivery bots in the picture, doing who the hell knows what. Are they heading back to base for the night? Off to an all-hands meeting? Or perhaps they're on strike and working the picket line? Hard to say, but it's interesting behavior for these things.

#hackadaycolumns #hackadaylinks #audioclip #boringpeople #deliverybot #electronbeam #ingenuity #jezero #mars #metal3dprinting #perseverance #starship #whatsthatsound

The Metal 3D Printing Hack Chat Brings the Heat

At this point, it's safe to say the novelty of desktop 3D printing has worn off. The community has largely come to terms with the limitations of extruded plastics, and while we still vehemently believe that it's a transformative technology, we'll admit there aren't too many applications where a $200 USD printer squirting out PLA is truly the best tool for the job.

But rather than looking at today's consumer 3D printer market as the end of the line, what if it's just the beginning? With the problems of slicing, motion control, and extrusion more or less solved when it comes to machines that print in plastic, is it finally time to turn our attention to the unique problems inherent in building affordable metal printers? Agustin Cruz certainly thinks so, which is why he took to the Hack Chat this week to talk about his personal vision for an open source 3D printer that can turn powdered metals into solid objects by way of a carefully controlled electron beam.

To be clear, Agustin isn't suggesting you toss out your Creality anytime soon. Metal 3D printing will always be a niche within a niche, but for applications where even advanced engineering plastics like PEI and PEEK simply won't do, he argues the community needs to have a cheap and accessible option. Especially for developing and low income countries where traditional manufacturing may be difficult. The machine he's been working on wouldn't be outside the capabilities of an individual to build and operate, but at least for right now the primary target is hospitals, colleges, and small companies.

The Chat was full of technical questions about Agustin's design, and he wasn't shy about tackling them. Some wondered why he decided to sinter the metal powder with an electron gun when solid-state lasers are cheap, easily available, and relatively straightforward to work with. But while the laser might seem like the easier solution on the surface, Agustin points out that using a magnetically focused electron beam gives his printer some unique capabilities.

For example, he can easily defocus the beam and pass it over the entire build plate to pre-heat the powder. The steerable beam doesn't require mirrors either, which not only reduces the weight and complexity of the machine, but in theory should allow for faster print speeds. The beam can be moved in the X/Y dimensions with an accuracy of 0.01 mm, and while the beam diameter is currently a respectable 0.5 mm, Agustin says he's working on bringing that down to 0.1 mm for high detail work. The temperature at the focal point of the beam is between 1,400 and 1,500 °C, which he notes is not only hot enough to melt the powdered metal, but can also weld stainless steel.

But, there's a downside. As brought up by several people in the Chat, using an electron beam requires the build chamber be pulled down to a vacuum. Some wondered how the fine metal powder would react to vacuum conditions, while others noted that oil from the diffusion pump would likely contaminate the powder. Then of course there's the inevitable difficulty in sealing the chamber, as well as the added bulk and weight such a structure brings to the table. Still, Agustin maintains the concept works well enough in his proof of concept machine, and believes pulling a vacuum will always be easier than producing a high-power laser beam.

Speaking of which, Agustin says his prototype is roughly 70% complete as of right now. He's got the stainless steel vacuum chamber that encapsulates the 5 cm diameter build area, the pumps to pull it down, the custom-built electron gun, and the necessary power supply and sensors to drive it all safely. It consumes around 1,500 watts while in operation, of which 100 watts is devoted to the electron gun itself. What he doesn 't have right now is a Z axis, but it sounds like the design is already rattling around in his head.

We're very glad Agustin was able to take the time to talk with the community about his project, and hope it gets more people thinking about the possibilities of 3D printing with metal. We'll be keeping a close eye on his prototype over the coming months to see how things develop, and we think you should to. Will his electron beam concept pan out? Will laser sintering end up being the more successful approach? Honestly we don't know, but we're eager to find out.

The Hack Chat is a weekly online chat session hosted by leading experts from all corners of the hardware hacking universe. It 's a great way for hackers connect in a fun and informal way, but if you can't make it live, these overview posts as well as the transcripts posted to Hackaday.io make sure you don't miss out.

#hackadaycolumns #3dprinting #electronbeam #electronbeamwelding #hackchat #lasersintering #metal3dprinter #powderedmetal