Hydrodipping 101

July 15, 2017 by Dan Maloney 34 Comments

Style counts, and sometimes all it takes to jazz up the product of a 3D-printer is a 2D printer and a how-to guide on hydrographic printing.

Hydrographic printing, sometimes called hydrodipping, is a process for transferring graphics onto complex-shaped objects in one simple step. A design is printed on a special film which is then floated on the surface of a tank of water. The object to be decorated is carefully dipped into the water right through the film and the design wraps around all the nooks and crannies in one step.

The video tutorial below details the steps to hydrographic printing and outlines how easy the method has become with the availability of water transfer films for inkjet printers. The film is polyvinyl acetate, which is essentially white glue and hence quite soluble in water. The film dissolves and leaves the ink floating on the surface, ready for dipping.

The video lists quite a few tips for optimizing the process for 3D-printed parts and should let you decorate your parts quickly and easily. And once you master the basics, you might want to look at mathematically warping your design to hydrodip complex surfaces.

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Behind The Scenes At A Professional Fireworks Show

July 14, 2017 by John Baichtal 18 Comments

Have you ever wondered what goes on behind the scenes at a big fireworks show? Last year [Kenneth] was asked to help manually ignite a fireworks show, and this consisted of him running down a row of shells with a road flare, lighting each one in turn. He apparently did so well that this year worked another show, this one with a more complicated setup.

The show [Kenneth] helped run consisted of 950 three-inch shells, wired in series into small groups, plus another 150 in 25-shell clusters used for the finale. The fireworks were organized in racks consisting of five three-inch diameter tubes of HDPE secured together by 2x4s. Each tube held a shell, and each shell came pre-wired with both a match fuse and electrically-triggered squib. Each squib or series of squibs connects to 45-channel breakouts, which connect to a control board.

Even after the show was completed, [Kenneth] had work to do, walking around and looking in each tube to see if there are any unfired shells. The dual wiring is so the shell can be fired with a flare if the squib is a dud. In this show they found six shells, and [Kenneth] was tasked with setting off those last shells with a road flare—otherwise they’d have to use a licensed and placarded vehicle just to transport a few shells.

For more fireworks goodness checkout this beautiful Arduino fireworks controller and this network-controlled fireworks launcher.

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A 3D Scanner That Archimedes Could Get Behind

July 14, 2017 by Dan Maloney 48 Comments

3D-scanning seems like a straightforward process — put the subject inside a motion control gantry, bounce light off the surface, measure the reflections, and do some math to reconstruct the shape in three dimensions. But traditional 3D-scanning isn’t good for subjects with complex topologies and lots of nooks and crannies that light can’t get to. Which is why volumetric 3D-scanning could become an important tool someday.

As the name implies, volumetric scanning relies on measuring the change in volume of a medium as an object is moved through it. In the case of [Kfir Aberman] and [Oren Katzir]’s “dip scanning” method, the medium is a tank of water whose level is measured to a high precision with a float sensor. The object to be scanned is dipped slowly into the water by a robot as data is gathered. The robot removes the object, changes the orientation, and dips again. Dipping is repeated until enough data has been collected to run through a transformation algorithm that can reconstruct the shape of the object. Anywhere the water can reach can be scanned, and the video below shows how good the results can be with enough data. Full details are available in the PDF of their paper.

While optical 3D-scanning with the standard turntable and laser configuration will probably be around for a while, dip scanning seems like a powerful method for getting topological data using really simple equipment.

[wpvideo xx88I1SN]

Thanks to [bmsleight] for the tip.

A Neural Network Can Now Be Your Writing Assistant

July 14, 2017 by Cameron Coward 15 Comments

Writing is a difficult job; though, as a primarily word-based site, we may be a little biased here at Hackaday. Not only does a writer have to know the basics, like what a semicolon is and when to use one, they also need to build sentences that convey information in a manner that is pleasant to read. As many commenters like to point out, even we struggle with this on occasion (lauded and scholarly as we are).

Wouldn’t it be better if we could let our computers do the heavy lifting for us? After all, a monkey with infinite time will eventually write Shakespeare and all that. Surely, a computer can be programmed to do all that fancy word assembly while we sit back and enjoy some coffee. Well, that’s what [Robin Sloan] set out to do with a recurrent neural network-powered writing assistant.

Alright, so it doesn’t actually write completely on its own. Instead, [Robin’s] software takes advantage of [JC Johnson’s] torch-rnn project, and integrates it into Atom to autocomplete sentences. [Robin] trained his neural network on hundreds of old issues of the sci-fi magazines Galaxy and IF Magazine, which are available at the Internet Archive. Once the server and corresponding Atom package are installed, a writer can simply push the Tab key and the sentence will be completed.

The results are interesting. [Robin] himself says “it’s like writing with a deranged but very well-read parrot on your shoulder.” While it’s not likely to be used as a serious writing tool anytime soon, the potential is certainly intriguing. When trained on relevant source material, the integration into software like Atom could be very useful. If a neural network can compose music, surely it can write some silly tech articles.

[thanks to Tim Trzepacz for the tip!]

Typewriter image: LjL (Public domain).

Shed Pounds And Inches While Binge Watching Netflix

July 13, 2017 by Dan Maloney 33 Comments

Feel like breaking out of your streaming-induced vegetative state but can’t seem to break the binge-watching cycle? Maybe you’re a candidate for this exercise bike that controls how much Netflix you watch.

The concept behind [Roboro]’s anti-couch potato build is simple — just keep pedaling and you get to keep watching. The details are pretty simple too and start with an Arduino monitoring the signal coming from a jack thoughtfully provided by the manufacturer of his exercise bike. The frequency of the square wave is translated into a speed which a Python script on a PC reads over USB. Once a Netflix stream is started, dropping below the user-defined speed pauses the movie. The video below shows it doing its thing.

Improvements readily spring to mind, like adding a speed buffer so that pedaling faster lets you bank some streaming time and earn a rest. Maybe it could somehow integrate with these Netflix-enabled socks, or even with the Netflix and Chill button. But those sort of defeat the purpose a bit.

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ESP8266 Dev Board Sports Flying Squirrel PCB Art

July 12, 2017 by John Baichtal 14 Comments

[Jarrett] has a box of Nokia phone batteries and decided to use them in a project. He designed and built WiFi throwies— these consist of ESP8266 WiFi chips attached to custom PCBs and powered by Nokia phone batteries. The board charges LiPoly/Li-Ion batteries over USB with the help of a MCP73831 charger chip and has USB-serial on-board. It’s much more of a powered ESP8266 dev board than a throwie, but we’ll give [Jarrett] the benefit of the doubt.

The PCB ended up larger than [Jarrett] would have liked, because of the size requirements of the phone battery connected to it. However, this gave him the canvas to create some fun PCB art. After designing the board he imported the Gerbers into Adobe Photoshop and converted each layer into a monocolor image based on the material of that layer—purple for OSHPark’s stencil mask, beige for DirtyPCB’s FR4, and so on. One challenge [Jarrett] encountered was how to get the art back into Altium Circuit Maker, his layout program of choice. After playing around with different methods for a few days, he wrote a tutorial sharing what he found out.

HaD has covered WiFi throwies before. We also appreciate a beautiful circuit board. Check out our posts on turning PCBs into art and making lapel pins out of circuit board fiberglass.

Old Rabbit Ears Optimized For Weather Satellite Downlink

July 10, 2017 by Dan Maloney 10 Comments

Communicating with a satellite seems like something that should take a lot of equipment. A fancy antenna and racks full of receivers, filters, and amplifiers would seem to be the entry-level suite of gear. But listening to a weather satellite with an old pair of rabbit ears and an SDR dongle? That’s a thing too.

There was a time when a pair of rabbit ears accompanied every new TV. Those days are gone, but [Thomas Cholakov (N1SPY)] managed to find one of the old TV dipoles in his garage, complete with 300-ohm twinlead and spade connectors. He put it to work listening to a NOAA weather satellite on 137 MHz by configuring it in a horizontal V-dipole arrangement. The antenna legs are spread about 120° apart and adjusted to about 20.5 inches (52 cm) length each. The length makes the antenna resonant at the right frequency, the vee shape makes the radiation pattern nearly circular, and the horizontal polarization excludes signals from the nearby FM broadcast band and directs the pattern skyward. [Thomas] doesn’t mention how he matched the antenna’s impedance to the SDR, but there appears to be some sort of balun in the video below. The satellite signal is decoded and displayed in real time with surprisingly good results.

Itching to listen to satellites but don’t have any rabbit ears? No problem — just go find a cooking pot and get to it.

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