Pack Your Plywood Cuts With Genetic Algortihms

January 22, 2016 by Elliot Williams 42 Comments

Reading (or writing!) Hackaday, we find that people are often solving problems for us that we didn’t even know that we had. Take [Jack Qiao]’s SVGnest for instance. If you’ve ever used a laser cutter, for instance, you’ve probably thought for a second or two about how to best pack the objects into a sheet, given it your best shot, and then moved on. But if you had a lot of parts, and their shapes were irregular, and you wanted to minimize materials cost, you’d think up something better.

SVGnest, which runs in a browser, takes a bunch of SVG shapes and a bounding box as an input, and then tries to pack them all as well as possible. Actually optimizing the placement is a computationally expensive proposition, and that’s considering the placement order to be fixed and allowing only 90 degree rotations of each piece.

Once you consider all the possible orders in which you place the pieces, it becomes ridiculously computationally expensive, so SVGnest cheats and uses a genetic algorithm, which essentially swaps a few pieces and tests for an improvement many, many times over. Doing this randomly would be silly, so the routine packs the biggest pieces first, and then back-fills the small ones wherever they fit, possibly moving the big ones around to accommodate.

That’s a lot of computational work, but the end result is amazing. SVGnest packs shapes better than we could ever hope to, and as well as some commercial nesting software. Kudos. And now that the software is written, as soon as you stumble upon this problem yourself, you have a means to get to the solution. Thanks [Jack]!

DIY Laser Lumia Lights Up The Night

January 15, 2016 by James Hobson 20 Comments

Lasers are awesome, and as the technology continues to advance, they keep getting cheaper! If you’ve ever wanted your own laser light show in your man cave, it’s never been easier.

In the 70’s [rgrokett] was a planetarium technician, responsible for building and operating laser shows. Back then, the laser modules were huge and expensive. After being reminded of days gone past, thanks to an article about laser light show operators, he decided to try his own hand at building a Low-cost Laser Lumia Lightshow.

And it couldn’t be easier.

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Laser Cutting A Bread Knife

January 10, 2016 by James Hobson 19 Comments

What started out as simply a question of whether or not they could… [G2AS] decided to try making a laser cut serrated bread knife — out of plastic.

Now from a distance this may look like they just took their laser cutter and cut out the pattern of a knife, with a jigsaw edge. But no, they actually laser cut a jig which allowed them to cut the serrated edge on an angle, creating an actual sharp edge. It’s quite the setup, but a pretty awesome result. Continue reading “Laser Cutting A Bread Knife” →

Laser Cut Map Taken To The Next Level

December 29, 2015 by James Hobson 18 Comments

For Christmas this year, [Scottshambaugh] decided to make his family a map of their hometown — Portland, ME. Using topographical map data, he made this jaw-dropping 3D map, and it looks amazing.

He started by exporting the elevation data of Portland using software called QGIS, a free opensource geographical information system — it’s extremely powerful software, but takes a bit to learn. Luckily, [Scott] made a tutorial for us. All you need to do is add the road data, put all the slices into an illustrator file, clean up some of the files, and you’re ready to start laser cutting.

He used 1/8th thick sheets of Baltic birch plywood, a staple material around laser cutters because it burns quickly and easily and is very flexible, which means that it’s harder to break. The map measures 12″ x 24″ — but once it’s laser cut, be ready for a multi-leveled jigsaw puzzle! The small pieces of elevation data can be very tricky!

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Seeing Around Corners With Frickin’ Lasers

December 14, 2015 by James Hobson 31 Comments

Researchers at the University of Edinburgh and Heriot-Watt University have created a sensor that can see around corners using lasers, high speed cameras, and some intense data processing. They can essentially turn a laser light source into a virtual mirror to look through.

Led by [Genevieve Gariepy], the team has been able to prove their research in a lab setting, and are now trying to refine it to work in the real world. While the animated image above makes the system seem rather simple, the tech behind it makes our heads hurt.

The timing measurement alone for the laser light to bounce off the hidden object and be reflected to where the camera can see it needs to be accurate down to the 500 billionth of a second (500 nanoseconds). Five hundred billionths.

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Raspberry Pi Communication Via LASER

December 12, 2015 by Al Williams 28 Comments

[Nick Touran] wanted to make two Raspberry Pi’s communicate wirelessly. There are lots of options, but [Nick] used a LASER and a photoresistor, along with Morse code. If you don’t find Morse code fancy enough, you could always refer to it as OOK (on/off keying). The circuit uses a common LASER module and an ordinary photoresistor that varies in resistance based on light. A resistor forms a voltage divider with the photoresistor and an external A/D reads the resulting voltage.

The circuit works, but we couldn’t help but notice a few items. Not all photoresistors are as sensitive to the same light wavelengths, so for the maximum range you’d want to pick a particular photoresistor. While the analog to digital converter is certainly workable, we couldn’t help but wonder if you couldn’t set up the divider to use the inherent threshold of the Raspberry Pi’s input pins for a simpler circuit. Of course, if you used the same technique with an Arduino, you could use the built-in A/D converter, and the A/D converter is probably easier to get working.

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Laser Cut-and-Weld Makes 3D Objects

December 6, 2015 by Elliot Williams 19 Comments

Everybody likes 3D printing, right? But it’s slow compared to 2D laser cutting. If only there were a way to combine multiple 2D slices into a 3D model. OK, we know that you’re already doing it by hand with glue and/or joints. But where’s the fun in that?

LaserStacker automates the whole procedure for you. They’ve tweaked their laser cutter settings to allow not just cutting but also welding of acrylic. This lets them build up 3D objects out of acrylic slices with no human intervention by first making a cutting pass at one depth and then selectively re-welding together at another. And they’ve also built up some software, along with a library of functional elements, that makes designing these sort of parts easier.

There’s hardly any detail on their website about how it works, so you’ll have to watch the video below the break and make some educated guesses. It looks like they raise the cutter head upwards to make the welding passes, probably spreading the beam out a bit. Do they also run it at lower power, or slower? We demand details!

Anyway, check out the demo video at 3:30 where they run through the slice-to-depth and heal modes through their paces. It’s pretty impressive.

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