Day: December 17, 2019

Humongous 3D Printer Produces Boat And Challenges

December 17, 2019 by 27 Comments

We’ve seen some pretty big polymer 3D printers, but nothing quite as big as the University of Maine’s 3D printer with a 22,000 ft³  (623 m³) build volume. It holds the Guinness World Record for the largest polymer 3D printer, and with that size comes some interesting challenges and advantages.

You might have already seen the video of it printing an entire patrol boat hull in a single piece, and would have noticed how it printed at a 45° angle. Due to the sheer weight and thermal mass of the print bead, it cannot bridge more than an inch, since it’ll just sag. A 45° overhang angle is about all it can manage, but since the layers can be tilted at that angle, it ends up being able to print horizontal roofs with no support. A 10 mm nozzle is used and the extruded line ends up being 12.5 mm in diameter with a 5 mm layer height. The boat mentioned above was printed with carbon ABS, but it can reportedly use almost any thermoplastic. It looks like the extruder is a screw extruder from an injection moulding machine, and is likely fed with pellets, which is a lot more practical than filament at this scale. Check out the video below by [Paul Bussiere] who works in the Advanced Structures & Composites Center at the University. He also does a very interesting interview with his boss, [James M. Anderson].

The 45° layer angle is very similar to how some infinite build volume 3D printers work. For something more within the reach of the average hacker, check out the tool changing Jubilee.
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Modulated Pilot Lights Anchor AR To Real World

December 17, 2019 by 26 Comments

We’re going to go out on a limb here and say that wherever you are now, a quick glance around will probably reveal at least one LED. They’re everywhere – we can spot a quick half dozen from our desk, mostly acting as pilot lights and room lighting. In those contexts, LEDs are pretty mundane. But what if a little more flash could be added to the LEDs of the world – literally?

That’s the idea behind LightAnchors, which bills itself as a “spatially-anchored augmented reality interface.” LightAnchors comes from work at [Chris Harrison]’s lab at Carnegie Mellon University which seeks new ways to interface with computers, and leverages the ubiquity of LED point sources and the high-speed cameras on today’s smartphones. LightAnchors are basically beacons of digitally encoded data that a smartphone can sense and decode. The target LED is modulated using amplitude-shift keying and each packet contains a data payload and parity bits along with a pre- and post-amble sequence. Software on the phone uses the camera to isolate the point source, track it, and pull the data out of it, which is used to create an overlay on the scene. The video below shows a number of applications, ranging from displaying guest login credentials through the pilot lights on a router to modulating the headlights of a rideshare vehicle so the next fare can find the right car.

An academic paper (PDF link) goes into greater depth on the protocol, and demo Arduino code for creating LightAnchors is thoughtfully provided. It strikes us that the two main hurdles to adoption of LightAnchors would be convincing device manufacturers to support them, and advertising the fact that what looks like a pilot light might actually be something more, but the idea sure beats fixed markers for AR tracking.

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