Hackaday Links: October 20, 2019

It’s Nobel season again, with announcements of the prizes in literature, economics, medicine, physics, and chemistry going to worthies the world over. The wording of the Nobel citations are usually a vast oversimplification of decades of research and end up being a scientific word salad. But this year’s chemistry Nobel citation couldn’t be simpler: “For the development of lithium-ion batteries”. John Goodenough, Stanley Whittingham, and Akira Yoshino share the prize for separate work stretching back to the oil embargo of the early 1970s, when Goodenough invented the first lithium cathode. Wittingham made the major discovery in 1980 that adding cobalt improved the lithium cathode immensely, and Yoshino turned both discoveries into the world’s first practical lithium-ion battery in 1985. Normally, Nobel-worthy achievements are somewhat esoteric and cover a broad area of discovery that few ordinary people can relate to, but this is one that most of us literally carry around every day.

What’s going on with Lulzbot? Nothing good, if the reports of mass layoffs and employee lawsuits are to be believed. Aleph Objects, the Colorado company that manufactures the Lulzbot 3D printer, announced that they would be closing down the business and selling off the remaining inventory of products by the end of October. There was a reported mass layoff on October 11, with 90 of its 113 employees getting a pink slip. One of the employees filed a class-action suit in federal court, alleging that Aleph failed to give 60 days notice of terminations, which a company with more than 100 employees is required to do under federal law. As for the reason for the closure, nobody in the company’s leadership is commenting aside from the usual “streamlining operations” talk. Could it be that the flood of cheap 3D printers from China has commoditized the market, making it too hard for any manufacturer to stand out on features? If so, we may see other printer makers go under too.

For all the reported hardships of life aboard the International Space Station – the problems with zero-gravity personal hygiene, the lack of privacy, and an aroma that ranges from machine-shop to sweaty gym sock – the reward must be those few moments when an astronaut gets to go into the cupola at night and watch the Earth slide by. They all snap pictures, of course, but surprisingly few of them are cataloged or cross-referenced to the position of the ISS. So there’s a huge backlog of beautiful but unknown cities around the planet that. Lost at Night aims to change that by enlisting the pattern-matching abilities of volunteers to compare problem images with known images of the night lights of cities around the world. If nothing else, it’s a good way to get a glimpse at what the astronauts get to see.

Which Pi is the best Pi when it comes to machine learning? That depends on a lot of things, and Evan at Edje Electronics has done some good work comparing the Pi 3 and Pi 4 in a machine vision application. The SSD-MobileNet model was compiled to run on TensorFlow, TF Lite, or the Coral USB accelerator, using both a Pi 3 and a Pi 4. Evan drove around with each rig as a dashcam, capturing typical street scenes and measuring the frame rate from each setup. It’s perhaps no surprise that the Pi 4 and Coral setup won the day, but the degree to which it won was unexpected. It blew everything else away with 34.4 fps; the other five setups ranged from 1.37 to 12.9 fps. Interesting results, and good to keep in mind for your next machine vision project.

Have you accounted for shrinkage? No, not that shrinkage – shrinkage in your 3D-printed parts. James Clough ran into shrinkage issues with a part that needed to match up to a PCB he made. It didn’t, and he shared a thorough analysis of the problem and its solution. While we haven’t run into this problem yet, we can see how it happened – pretty much everything, including PLA, shrinks as it cools. He simply scaled up the model slightly before printing, which is a good tip to keep in mind.

And finally, if you’ve ever tried to break a bundle of spaghetti in half before dropping it in boiling water, you likely know the heartbreak of multiple breakage – many of the strands will fracture into three or more pieces, with the shorter bits shooting away like so much kitchen shrapnel. Because the world apparently has no big problems left to solve, a group of scientists has now figured out how to break spaghetti into only two pieces. Oh sure, they mask it in paper with the lofty title “Controlling fracture cascades through twisting and quenching”, but what it boils down to is applying an axial twist to the spaghetti before bending. That reduces the amount of bending needed to break the pasta, which reduces the shock that propagates along the strand and causes multiple breaks. They even built a machine to do just that, but since it only breaks a strand at a time, clearly there’s room for improvement. So get hacking!

Coandă Effect Makes A Better Hovercraft Than A Quadcopter

Leaving no stone unturned in his quest for alternative and improbable ways to generate lift, [Tom Stanton] has come up with some interesting aircraft over the years. But this time he isn’t exactly flying, with this unusual Coandă effect hovercraft.

If you’re not familiar with the Coandă effect, neither were we until [Tom] tried to harness it for a quadcopter. The idea is that air moving at high speed across a curved surface will tend to follow it, meaning that lift can be generated. [Tom]’s original Coandă-copter was a bit of a bust – yes, there was lift, but it wasn’t much and wasn’t easy to control. He did notice that there was a strong ground effect, though, and that led him to design the hovercraft. Traditional hovercraft use fans to pressurize a plenum under the craft, lifting it on a low-friction cushion of air. The Coandă hovercraft uses the airflow over the curved hull to generate lift, which it does surprisingly well. The hovercraft proved to be pretty peppy once [Tom] got the hang of controlling it, although it seemed prone to lifting off as it maneuvered over bumps in his backyard. We wonder if a control algorithm could be devised to reduce the throttle if an accelerometer detects lift-off; that might make keeping the craft on the ground a bit easier.

As always, we appreciate [Tom]’s builds as well as his high-quality presentation. But if oddball quadcopters or hovercraft aren’t quite your thing, you can always put the Coandă effect to use levitating screwdrivers and the like.

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3D-Printed Transformer Disappoints, But Enlightens

Transformers are deceptively simple devices. Just coils of wire sharing a common core, they tempt you into thinking you can make your own, and in many cases you can. But DIY transformers have their limits, as [Great Scott!] learned when he tried to 3D-print his own power transformer.

To be fair, the bulk of the video below has nothing to do with 3D-printing of transformer coils. The first part concentrates on building transformer cores up from scratch with commercially available punched steel laminations, in much the same way that manufacturers do it. Going through that exercise and the calculations it requires is a great intro to transformer design, and worth the price of admission alone. With the proper number of turns wound onto a bobbin, the laminated E and I pieces were woven together into a core, and the resulting transformer worked pretty much as expected.

The 3D-printed core was another story, though. [Great Scott!] printed E and I pieces from the same iron-infused PLA filament that he used when he 3D-printed a brushless DC motor. The laminations had nowhere near the magnetic flux density of the commercial stampings, though, completely changing the characteristics of the transformer. His conclusion is that a printed transformer isn’t possible, at least not at 50-Hz mains frequency. Printed cores might have a place at RF frequencies, though.

In the end, it wasn’t too surprising a result, but the video is a great intro to transformer design. And we always appreciate the “DIY or Buy” style videos that [Great Scott!] does, like his home-brew DC inverter or build vs. buy lithium-ion battery packs.

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[Ben Krasnow] Looks Inside Film Camera Date Stamping

Honestly, we never wondered how those old film cameras used to put the date stamp in the lower right-hand corner of the frame. Luckily, [Ben Krasnow] does not suffer from this deplorable lack of curiosity, and his video teardown of a date-stamping film camera back (embedded below) not only answers the question, but provides a useful lesson in value engineering.

For the likely fair fraction of the audience who has never taken a photo on film before, cheap 35-mm cameras were once a big thing. They were really all one had for family snapshots and the like unless you wanted to invest in single-lens reflex cameras and all the lenses and accessories. They were miles better than earlier cartridge cameras like the 110 or – shudder – Disc film, and the cameras started getting some neat electronic features too. One was the little red-orange date stamp, which from the color we – and [Ben] assumed was some sort of LED pressed up against the film, but it ends up being much cooler than that.

Digging into the back of an old camera, [Ben] found that there’s actually a tiny projector that uses a mirror to fold the optical path between the film and a grain-of-wheat incandescent bulb. An LCD filter sits in the optical path, but because it’s not exactly on the plane of the film, it actually has to project the image onto the film. The incandescent bulb acts as a point source and the mirror makes the optical path long enough that the date stamp image appears sharp on the film. It’s cheap, readily adapted to other cameras, and reliable.

Teardowns like this aren’t fodder for [Ben]’s usual video fare, which tends more toward homemade CT scanners and Apollo-grade electroluminescent displays, but this was informative and interesting, too.

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Hacking Diabetes Hack Chat

Join us on Wednesday, October 16 at noon Pacific for the Hacking Diabetes Hack Chat with Dana Lewis!

When your child is newly diagnosed with Type 1 diabetes (T1D), everyone is quick to point out, “It’s a great time to be a diabetic.” To some degree, that’s true; thanks to genetically engineered insulin, more frequent or even continuous glucose monitoring (CGM), and insulin infusion pumps, diabetics can now avoid many of the truly terrifying complications of a life lived with chronically elevated blood glucose, like heart disease, kidney failure, blindness, and amputations.

Despite these advances, managing T1D can be an overwhelming task. Every bite of food, every minute of exercise, and every metabolic challenge has to be factored into the calculations for how much insulin to take. Diabetics learn to “think like a pancreas,” but it’s never good enough, and the long-promised day of a true artificial pancreas always seems to remain five years in the future.

Dana Lewis is one diabetic who decided not to wait. After realizing that she could get data from her CGM, she built a system to allow friends and family to monitor her blood glucose readings remotely. With the addition of a Raspberry Pi and some predictive algorithms, she later built an open-source artificial pancreas, which she uses every day. And now she’s helping others take control of their diabetes and build their own devices through OpenAPS.org.

Join us on the Hack Chat as Dana drops by to discuss OpenAPS and her artificial pancreas. We’ll find out what her background is – spoiler alert: she wasn’t a hacker when she started this – what challenges she faced, the state of the OpenAPS project, and where she sees the artificial pancreas going.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, October 16 at 12:00 PM Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

[Dana Lewis image source: GeekWire]

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Gutted Hoverboard Becomes Formidable Track-Drive Robot

When “hoverboards” first came out, you may have been as disappointed as we were that they did not even remotely fulfill the promises of Back to the Future II. Nothing more than a fancified skateboard, hoverboards are not exactly groundbreaking technology. That doesn’t mean they’re not useful platforms for hacking, though, as this hoverboard to track-propelled robot tank conversion proves.

Most of the BOM for this build came from the junk bin – aluminum extrusions, brackets, and even parts cannibalized from a 3D-printer. But as [pasoftdev] points out, the new-in-box hoverboard was the real treasure trove of components. The motors, the control and driver electronics, and the big, beefy battery were all harvested and mounted to the frame. To turn the wheels into tracks, [pasoftdev] printed some sprockets to fit around the original tires. The tracks were printed in sections and screwed to the wheels. Idlers were printed in sections too, using central hubs and a clever method for connecting everything together into a sturdy wheel. Printed tank tread links finished the rolling gear eventually; each of the 34 pieces took almost five hours to print. The dedication paid off, though, as the 15-kg tank is pretty powerful; the brief video below shows it towing an office chair around without any problems.

We noticed that [pasoftdev] found the assembly of the tread links a bit problematic. These 3D-printed links that are joined by Airsoft BBs might make things a little easier next time.

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Hackaday Links: October 13, 2019

Trouble in the Golden State this week, as parts of California were subjected to planned blackouts. Intended to prevent a repeat of last year’s deadly wildfires, which were tied in part to defective electrical distribution equipment, the blackouts could plunge millions in the counties surrounding Sacramento into the dark for days. Schools have canceled classes, the few stores that are open are taking cash only, and hospitals are running on generators. It seems a drastic move for PG&E, the utility that promptly went into bankruptcy after being blamed for last year’s fires, but it has the support of the governor, so the plan is likely to continue as long as the winds do. One group is not likely to complain, though;  California amateur radio operators must be enjoying a greatly decreased noise floor in the blackout areas, thanks to the loss of millions of switch-mode power supplies and their RF noise.

Good news, bad news for Fusion 360 users. Autodesk, the company behind the popular and remarkably capable CAD/CAM/CAE package, has announced changes to its licensing scheme, which went into effect this week. Users no longer have to pay for the “Ultimate” license tier to get goodies like 5-axis machining and generative design tools, as all capabilities are now included in the single paid version of Fusion 360. That’s good because plenty of users were unwilling to bump their $310 annual “Standard” license fee up to $1535 to get those features, but it’s bad because now the annual rate goes to $495. In a nice nod to the current userbase, those currently on the Standard license, as well as early adopters, will get to keep the $310 annual rate as long as they renew, and The $495 pricing tier went into effect in November of 2018, while anyone still on the $310 annual price was grandfathered in (and will remain to be). At that time there was still a $1535 tier called Ultimate, whose price will now be going away but the features remain in the $495 tier which is now the only pricing option for Fusion 360. Ultimate users will see a $1040 price drop. As for the current base of freeloaders like yours truly, fear not: Fusion 360 is still free for personal, non-commercial use. No generative design or tech support for us, though. (Editor’s Note: This paragraph was updated on 10/14/2019 to clarify the tier changes after Autodesk reached out to Hackaday via email.)

You might have had a bad day at the bench, but was it as bad as Román’s? He tipped us off to his nightmare of running into defective Wemos D1 boards – a lot of them. The 50 boards were to satisfy an order of data loggers for a customer, but all the boards seemed caught in an endless reboot loop when plugged into a USB port for programming. He changed PCs, changed cables, but nothing worked to stop the cycle except for one thing: touching the metal case of the module. His write up goes through all the dead-ends he went down to fix the problem, which ended up being a capacitor between the antenna and ground. Was it supposed to be there? Who knows, because once that cap was removed, the boards worked fine. Hats off to Román for troubleshooting this and sharing the results with us.

Ever since giving up their “Don’t be evil” schtick, Google seems to have really embraced the alternative. Now they’re in trouble for targeting the homeless in their quest for facial recognition data. The “volunteer research studies” consisted of playing what Google contractors were trained to describe as a “mini-game” on a modified smartphone, which captured video of the player’s face. Participants were compensated with $5 Starbucks gift cards but were not told that video was being captured, and if asked, contractors were allegedly trained to lie about that. Contractors were also allegedly trained to seek out people with dark skin, ostensibly to improve facial recognition algorithms that notoriously have a hard time with darker complexions. To be fair, the homeless were not exclusively targeted; college students were also given gift cards in exchange for their facial data.

For most of us, 3D-printing is a hobby, or at least in service of other hobbies. Few of us make a living at it, but professionals who do are often a great source of tips and tricks. One such pro is industrial designer Eric Strebel, who recently posted a video of his 3D-printing pro-tips. A lot of it is concerned with post-processing prints, like using a cake decorator’s spatula to pry prints off the bed, or the use of card scrapers and dental chisels to clean up prints. But the money tip from this video is the rolling cart he made for his Ultimaker. With the printer on top and storage below, it’s a great way to free up some bench space.

And finally, have you ever wondered how we hackers will rebuild society once the apocalypse hits and mutant zombie biker gangs roam the Earth? If so, then you need to check out Collapse OS, the operating system for an uncertain future. Designed to be as self-contained as possible, Collapse OS is intended to run on “field expedient” computers, cobbled together from whatever e-waste can be scrounged, as long as it includes a Z80 microprocessor. The OS has been tested on an RC2014 and a Sega Master System so far, but keep an eye out for TRS-80s, Kaypros, and the odd TI-84 graphing calculator as you pick through the remains of civilization.