Photochromic Eggs: Not For Breakfast

April 18, 2017 by Lewin Day 17 Comments

Photochromic paint is pretty nifty – under exposure to light of the right wavelength, it’ll change colour. This gives it all kinds of applications for temporary displays. [Jiri Zemanek] decided to apply photochromic paint to an egg, utilising it to create stroboscopic patterns with the help of a laser.

Patterns for the egg are generated in MATLAB. A Discovery STM32 board acts as a controller, looking after the laser scanner and a stepper motor which rotates the egg. A phototransistor is used to sync the position of the laser and the egg as it rotates.

The photochromic paint used in this project is activated by UV light. To energize the paint, [Jiri] harvested a violet laser from a Blu-ray player, fitting it to a scanning assembly from a laser printer. Instead of scanning the laser across an imaging drum, it is instead scanned vertically on a rotating egg. Patterns can then be drawn on the egg, which fade over time as the paint gives up its stored energy.

[Jiri] exploits this by writing a variety of patterns onto the egg, which then animate in a manner similar to a zoetrope – when visualised under strobing light, the patterns appear to move. There are also a few holiday messages shown for Easter, making the egg all the more appropriate as a billboard.

If you like the idea of drawing on eggs but are put off by their non-uniform geometry, check out the Egg-bot. Video below the break.

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Submersible Robots Hunt Lice With Lasers

April 10, 2017 by James Hobson 54 Comments

De-lousing is a trying agricultural process. It becomes a major problem in pens which contain the hundreds of thousands of salmon farmed by Norwegians — the world’s largest salmon exporter — an environment which allows the parasite to flourish. To tackle the problem, the Stingray, developed by [Stingray Marine Solutions], is an autonomous drone capable of destroying the lice with a laser in the order of tens of thousands per day.

Introduced in Norway back in 2014 — and some areas in Scotland in 2016 — the Stingray floats in the salmon pen, alert and waiting. If the lice-recognition software (never thought you’d hear that term, huh?) detects a parasite for more than two frames in the video feed, it immediately annihilates it with a 530 nanometre-wide, 100 millisecond laser pulse from up to two metres away. Don’t worry — the salmon’s scales are reflective enough to leave it unharmed, while the pest is fried to a crisp. In action, it’s reminiscent of a point-defense laser on a spaceship.

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Two-Piece Boxes Thanks To Laser-Cut Flex Hinges

April 6, 2017 by Dan Maloney 14 Comments

It sounds like a challenge from a [Martin Gardner] math puzzle from the Scientific American of days gone by: is it possible to build a three-dimensional wooden box with only two surfaces? It turns out it is, if you bend the rules and bend the wood to make living hinge boxes with a laser cutter.

[Martin Raynsford] clearly wasn’t setting out to probe the limits of topology with these boxes, but they’re a pretty neat trick nonetheless. The key to these boxes is the narrow to non-existent kerf left by a laser cutter that makes interference fits with wood a reality. [Martin]’s design leverages the slot and tab connection we’re used to seeing in laser-cut boxes, but adds a living flex-hinge to curve each piece of plywood into a U-shape. The two pieces are then nested together like those old aluminum hobby enclosures from Radio Shack. His GitHub has OpenSCAD scripts to parametrically create two different styles of two-piece boxes so you can scale it up or (somewhat) down according to your needs. There’s also a more traditional three-piece box, and any of them might be a great choice for a control panel or small Arduino enclosure. And as a bonus, the flex-hinge provides ventilation.

Need slots and tabs for boxes but you’re more familiar with FreeCAD? These parametric scripts will get you started, and we’ll bet you can port the flex-hinge bit easily, too.

Sudo Make Me A Sandwich

March 30, 2017 by Anool Mahidharia 29 Comments

How do you like your Ham and Cheese sandwich? If you answered “I prefer it beefy”, look no further than [William Osman]’s Vin Diesel Ham and Cheese Sandwich! [Osman]’s blog tagline is “There’s science to do” but he is the first to admit this is science gone too far. When one of his followers, [Restroom Sounds], commented “Please sculpt a bust of [Vin Diesel] using laser cut cross-sections of laser sliced ham”, he just had to do it.

His friend [CameraManJohn] modeled the bust using Maya and [Osman] has provided links to download the files in case there’s the remote possibility that someone else wants to try this out. They picked the cheapest packs of sliced ham they could get from the supermarket — so technically, they did not actually laser slice the ham. For help with generating the slice outlines, they found the Slicer app for Autodesk’s Fusion 360 which did exactly what needed to be done. The app converts the 3D model into individual cross sections, similar to an MRI. It helps to measure the thickness of various samples of your raw material so that the Slicer output is not too stretched (or squished). The result is a set of numbered 2D drawings that can be sent to your laser cutter.

The rest of the video scores pretty high on the gross-o-meter, as [Osman] goes about laser cutting slices of ham (and a few slices of cheese), tasting laser cut ham (for Science, of course), and trying to prevent his computer from getting messed up. In the end, the sandwich actually turns out looking quite nice, although we will not comment on its taste. A pair of googly eyes adds character to the bust.

One problem is that the Slicer app does not optimise its results for efficient packing. with the smallest part occupying the same bounding box as the largest. This leads to a lot of wasted pieces of ham slices to be thrown away. [Bill] is still wondering what to do with his awesome sandwich, so if you have suggestions, chime in with your comments after you’ve seen the video linked below. If you know [Vin Diesel], let him know.

This isn’t [Osman]’s first adventure with crazy food hacks — here are a few tasty examples: a Toast-Bot that Butters For You (sometimes), a Laser-Cut Gingerbread Trailer Home, and a Pumpkin-Skinned BattleBot.

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Teensy Laser Harp Has Big Sound

March 20, 2017 by Kristina Panos 11 Comments

[Johan] has slipped down the rabbit hole of making musical instruments. His poison? Laser harp MIDI controllers. Having never made one before, he thought he would start small and then iterate using what he learned. Fortunately for us, [Johan] documented the process over on .io, essentially creating a step-by-step guide for building a simple but powerful 16-note laser harp.

Laser Harp I is built around a Teensy 3.2 and, of course, lasers pointed at LDRs. [Johan] used fairly low-power laser modules, which are slightly less blinding if you accidentally look at them for a second, but should still be taken seriously. He added four potentiometers to control the sensitivity, scale, octave, and the transposition. The sensitivity pot essentially accounts for the ambient light in the room. Although it only has 16 notes, Laser Harp I is ready to rock with over 30 different scales to choose from. Check out the brief demo that [Johan] put up on his Instagram.

If you try to build your own laser harp and get lost trying to follow [Johan]’s instructions, don’t worry. His well-commented code and lovely schematic will undoubtedly save you. Then you can move on to open-beam designs.

Burn Music On To Anything!

March 11, 2017 by James Hobson 17 Comments

If at first you don’t succeed, try, try, and try again. This is especially true when your efforts involve a salvaged record player, a laser cutter, and He-Man. Taking that advice to heart, maniac maker extraordinaire [William Osman] managed to literally burn music onto a CD.

Considering the viability of laser-cut records is dubious — especially when jerry-built — it took a couple frustrating tests to finally see results, all the while risking his laser’s lens. Eventually, [Osman]’s perseverance paid off. The lens is loosely held by a piece of delrin, which is itself touching a speaker blaring music. The vibrations of the speaker cause the lens to oscillate the focal point of the laser into a wavelength that is able to be played on a record player. You don’t get much of the high-end on the audio and the static almost drowns out the music, but it is most definitely a really shoddy record of a song!

Vinyl aficionados are certainly pulling their hair out at this point. For the rest of us, if you read [Jenny’s] primer on record players you’ll recognize that a preamplifier (the ‘phono’ input on your amp) is what’s missing from this setup and would surely yield more audible results.

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Tales Of A Cheap Chinese Laser Cutter

February 22, 2017 by Jenny List 51 Comments

The star turn of most hackspaces and other community workshops is usually a laser cutter. An expensive and fiddly device that it makes much more sense to own collectively than to buy yourself.

This isn’t to say that laser cutters are outside the budget of the experimenter though, we’re all familiar with the inexpensive table-top machines from China. Blue and white boxes that can be yours for a few hundred dollars, and hold the promise of a real laser cutter on your table.

Owning one of these machines is not always smooth sailing though, because their construction and choice of components are often highly variable. A thorough check and often a session of fixing the non-functional parts is a must before first power-on.

[Extreme Electronics] bought one, and in a series of posts documented the process from unboxing to cutting. Starting with a full description of the machine and what to watch for out of the box, then a look at the software. A plugin for Corel Draw was supplied, along with a dubious copy of Corel Draw itself. Finally we see the machine in operation, and the process of finding the proper height for beam focus by cutting an inclined plane of acrylic.

The series rounds off with a list of useful links, and should make interesting reading for anyone, whether they are in the market for a cutter or not.

These cutters/engravers have featured here before many times. Among many others we’ve seen one working with the Mach3 CNC software, or another driven by a SmoothieBoard.