Laser Cutting Orreries

An orrery is a clockwork model of the solar system, demonstrating the machinations of the planets traveling around the sun in a sublime pattern of epicycles. A tellurion is a subset of the orrery, showing the rotation of the Earth around the sun, and the orbit of the moon around the Earth. [HuidongT] created his own tellurion out of laser-cut parts and just a few bits of copper tubes and bearings.

This project was originally inspired by the holzmechanik, a tellurion constructed from plywood gears and brass tube. [HuidongT] saw a few shortcomings in this project: the Earth didn’t spin and the moon didn’t orbit with its natural five-degree inclination. [Huidong]’s tellurion would have these features and include an illuminated sun, demonstrate the change of the seasons, and show lunar and solar eclipses.

While there was a bit of math involved in figuring out the gearing, it’s not much: the Earth would go around the sun every 365.25 days, the moon would go around the Earth every 27.32 days, and there is a difference between sidereal and solar time. A quick script made quick work of the math, and anyone can easily find tools to create gears given a diameter and the number of teeth.

The fabrication of this tellurion was made with acrylic on a laser cutter with a handful of 3D printed parts. The electronics are simple enough — just a motor and a few LEDs, and the completed project works well enough. You can check out a video of the tellurium below.

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A Poor-Man’s Laser CNC Engraver

What do you get when you mix the disappointment that sometimes accompanies cheap Chinese electronics with the childhood fascination of torturing insects with a magnifying glass on a sunny day? You get a solar-powered CNC etcher, that’s what.

We all remember the days of focussing the sun on a hapless insect, or perhaps less sadistically on a green plastic army man or just a hunk of dry wood. The wonder that accompanied that intense white spot instantly charring the wood and releasing wisps of smoke stayed with you forever, as seemingly did the green spots in your vision. [drum303] remembered those days and used them to assuage his buyer’s remorse when the laser module on his brand new CNC engraver crapped out after the first 10 minutes. A cheap magnifying glass mounted to the laser holder and a sunny day, and he don’t need no stinkin’ lasers! The speed needs to be set to a super slow — 100mm per minute — and there’s the problem of tracking the sun, but the results are far finer than any of our childhood solar-artistic attempts ever were.

Do we have the makings of a possible performance art piece here? A large outdoor gantry with a big Fresnel lens that could etch a design onto a large piece of plywood would be a pretty boss beachside attraction. Of course, you’d need a simple solar tracker to keep things in focus.

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[Daito Manabe] Interview: Shocking!

We’ve loved [Daito Manabe]’s work for a while now. Don’t know [Daito]? Read this recent interview with him and catch up. Is he a hacker’s artist, or an artist’s hacker?

My personal favorite hack of his is laser painting apparatus from 2011. The gimmick is that he uses the way the phosphors fade out to create a greyscale image. Saying that is one thing, but watching it all come together in time is just beautiful.

Maybe you’ve seen his facial-electrocution sequencer (words we never thought we’d write! YouTube link). He’s taken that concept and pushed it to the limit — setting up the same sequences on multiple people make them look eerily like the sacks of meat that they are, until everyone laughs at the end of the experiment and they’re all back to being human.

Anyway, if you didn’t know [Daito], check out the rest of his work. Have any other favorite tech artists that we’re missing? Drop us a line.

Laser PCBs with LDGraphy

There are many, many ways to get a PCB design onto a board for etching. Even with practice however, the quality of the result varies with the process and equipment used. With QFN parts becoming the norm, the days of etch-resist transfers and a permanent marker are all but gone. Luckily, new and improved methods of Gerber transfer have be devised in recent years thanks to hackers across the world.

One such hacker, [Henner] is working on a project called LDGraphy in an attempt to bring high-resolution etching to the masses. LDGraphy is a laser lithography device that makes use of a laser and a Beaglebone green to etch the layout onto the board. The best part is that the entire BOM is claimed to cost under a $100 which makes it affordable to people on a budget.

The system is designed around a 500 mW laser and a polygon mirror scanner meant for a laser printer. The board with photoresist is linearly actuated in the X-axis using a stepper motor and the laser beam which is bounced off the rotating hexagonal mirror is responsible for the Y-axis. The time critical code for the Programmable Realtime Unit (PRU) of the AM335X processor is written in assembly for the fast laser switching. The enclosure is, naturally, a laser cut acrylic case and is made at [Henner]’s local hackerspace.

[Henner] has been hard at work calibrating his design and compensating for the inaccuracies of the components used. In the demo video below he presents a working version with a resolution of 6 mils which is wonderful considering the cost of the machine. He also shares his code on GitHub if you want to help out and you can track his updates on Google+. Continue reading “Laser PCBs with LDGraphy”

A Mechanical Laser Show with 3D-Printed Cams and Gears

Everyone knows how to make a POV laser display — low-mass, first-surface mirrors for the X- and Y-axes mounted on galvanometers driven rapidly to trace out the pattern. [Evan Stanford] found a simpler way, though: a completely mechanical laser show from 3D-printed parts.

The first 10 seconds of the video below completely explains how [Evan] accomplished this build. A pair of custom cams wiggles the laser pointer through the correct sequences of coordinates to trace the desired pattern out when cranked by hand through a 1:5 ratio gear train. But what’s simple in concept is a bit more complicated to reduce to practice, as [Evan] amply demonstrates by walking us through the math he used to transfer display shapes to cam profiles. If you can’t follow the math, no worries — [Evan] has included all the profiles in his Thingiverse collection, and being a hand model software guy by nature, he’s thoughtfully developed a program to automate the creation of cam profiles for new shapes. It’s all pretty slick.

Looking for more laser POV goodness? Perhaps a nice game of laser Asteroids would suit you.

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Holograms Can’t be Too Thin

We’ve seen the 3D phone fad come and go, with devices like the Evo 3D, that used a parallax barrier to achieve autostereoscopy (that is, 3D viewing without glasses). These displays aren’t holograms, they are just showing your eyes two different images like a 3D movie or a stereopticon. However, researchers from Australia and China are hoping to change that. They’ve developed a nano-hologram (their term) that is about 1000 times thinner than a human hair. You can see a video about the invention, below.

Conventional holograms modulate the phase of light to give the illusion of three-dimensional depth. But to generate the required phase shifts, those holograms need to be as thick as the optical wavelengths involved. The researchers claim the holograms are “simple” to make, but that depends on what you compare it to. You need some exotic materials, vacuum deposition gear, and a laser that can do femtosecond-long pulses.

The research team has broken this thickness limit with a 25 nanometer hologram. Their technique relies on a topological insulator material a novel quantum material that holds a low refractive index in the surface layer but a much higher refractive index in the bulk of the material. This forms an intrinsic optical resonant cavity which can enhance the phase shifts and makes holography possible.

The next step is to develop a rigid thin film to overlay an LCD screen. The current version has pixels at least ten times too large to be practical for that application, so that’s another hurdle to overcome.

We’ve seen screens that shoot 3D images on movies like Star Wars for years. This isn’t it yet, but it is the next step. Imagine a phone, a wrist watch, or a contact lens that could generate a holographic image. Or a garbage-can-sized robot.

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Metal 3D Printing: Insta-Layers

Selective Metal Sintering is cool but slow. Fear not, a technology that was initially developed to smooth and pattern laser beams is here to save the day, according to a new paper by Lawrence Livermore researchers.

In a paper titled “Diode-based additive manufacturing of metals using an optically-addressable light valve,” the researchers lay out a procedure for using an array of high-powered laser diodes among other things to print a whole layer of metal from powdered metal at one time. No more forward and backward, left and right. Just one bright flash and you’re done. Naturally, the technology is still in its infancy, but huge 3D printed metallic parts are something we’ve always hoped for.

According to [Matthews], the first author of the paper, the mojo of the process comes from a customized laser modulator: the Optically Addressable Light Valve which functions similarly to liquid crystal-based projectors but can handle the high energies associated with powerful lasers. There’s more information straight from the paper’s authors in this phys.org interview.

While it’s true that now is the time for direct metal 3D printing, it appears that for the time being the average hacker is stuck with alternative methods for printing metal. While it’s not the same, pewter casting with PLA might suffice.

Thanks to [Kevin] for sending this in!