Metal 3D Printing — a Dose of Reality

We have no doubt that hundreds of times a day a hacker is watching a 3D printer spew hot plastic and fantasizes about being able to print directly using metal. While metal printers are more common than ever, they are still out of reach for most people printing as a hobby. But as Mr. Spock once observed: “…you may find that having is not so pleasing a thing after all as wanting. It is not logical, but it is often true.” However, metal 3D printing has its own unique set of challenges. Texas A&M recently produced a short video explaining some of the design issues that you’ll encounter trying to make practical metal prints on an SLS (Selective Laser Melting) printer. You can see the video below.

The description says “It is more challenging to ‘metal 3D print’ a part than most people think. We’ve noticed the same even with plastic printers as friends will expect us to print the most outlandish things for them. What we like about this video is it helps to set expectations of the current state of the art so we’re not expecting far more than today’s metal printers can produce.

Among the features covered in the video are overhangs, which require supports. After removal, the surface is about like 80 grit sandpaper unless you perform further finishing. Just like plastic parts, warping and curling of large areas is a problem with metal. If you’ve ever been frustrated removing plastic support material, try having to ceramic grind metal supports off. They also use an EDM machine to cut especially tough supports, but it causes a lot of effort since it is likely to run through EDM wires and clog the filters.

We looked at recent advances in metal printing last year. We’ve seen homebrew machines that were little more than welders under computer control and we’ve seen plans by big players like HP to create metal prints, but at a steep price. Still, you can’t stop the march of 3D printing progress.

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We Were Really Overdue For Laser Jackets

Depending on who you talk to, everything is either fine, or we’re living in an oppressive cyberpunk dystopia in which we forgot to drench everything in colored neon lighting. There’s little to be done about the digital surveillance panopticon that stalks our every move, but as far as the aesthetic goes, [abetusk] is bringing the goods. The latest is a laser jacket, to give you that 2087 look in 2019.

The build starts with a leather jacket, which is festooned with 128 individual red laser diodes. These are ganged up in groups of 4, and controlled with 32 individual PWM channels using two PCA9685 controllers. An Arduino Nano acts as the brains of the operation, receiving input from a joystick and a microphone. This allows the user to control lighting effects and set the jacket to respond to sounds and music.

[abetusk] does a great job of conveying the tricks needed to successfully pull this off. The instructions should allow any curious maker to replicate the build at home, and code is available on Github to help run the show. There’s lots of detail on proper enclosures, connectors, and cabling techniques to avoid the wearer inadvertently pulling everything to bits when wearing the garment to the club. Remember, there’s nothing more punk than educating your friends.

It’s an eye-catching build that would be an excellent addition to any Neo-Chicago street gang wardrobe. It’s not the first time [abetusk] has graced these pages, either – there are electroluminescent looks, too. Video after the break.

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Building An Optically Pumped Laser Pointer

As a society, we’ve largely come together to agree that laser pointers are mostly useless. They’re now the preserve of university lecturers and those destined to wind up in a jail cell for harassing helicopter pilots. Most pointers are of the diode-pumped solid state variety. However, [Zenodilodon] treads a different path.

The laser cavity glows in operation, though it’s probably inadvisable to look directly at it.

Instead of the usual DPSS build, this pointer packs an optically pumped semiconductor laser, or OPSL. These lasers have the benefit of a wider selection of output wavelengths, and can be built to offer less variance in beam parameters such as divergence.

The build is an attractive one, with the pointer chassis being manufactured out of brass, with several components plated in yellow and rose gold. There’s even a sliding window to observe the laser cavity, which glows brightly in operation. [Zenodilodon] goes into great detail during the machining process, showing all the steps required to produce a visually appealing device.

It’s certainly one of the prettiest laser builds we’ve seen, and it’s always nice to see makers exploring different technologies. Similarly to our recently featured 1.4 W laser pointer, it’s largely a packaging operation, but if you’re building your own laser diodes at home – you know where to send ’em. Video after the break.

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Building A 1.4W Laser Pointer In A Tiny Housing

Laser pointers were cool for about 30 seconds when they first came out, before becoming immediately passé and doing absolutely nothing to improve the boss’s quarterly reports presentation. However, just as with boom boxes and sports cars, more power can always make things better. [Styropyro] was unimpressed with the weak and unreliable laser pointers he’d sourced from eBay, so gutted one and began a fresh build.

After fiddling with some basic 1mW eBay green lasers, [styropyro] had some fun turning up the wick by fiddling with the internal trimpots. This led to the quick and untimely death of the cheap laser diodes, leaving a compact laser pointer shell ripe for the hacking.

To replace the underwhelming stock components, [styropyro] chose a Nichia NDG7475 high-powered laser diode, fitting it into a small heatsink for thermal management. Current draw was far too high to use the original switch, so the stock housing’s button is instead used to switch a MOSFET which delivers the full current to the laser driver. To reach the higher output power of 1.4W, the laser diode is being run over specification at 2.3 amps. All this current draw would quickly overwhelm standard AAA batteries, so a pair of lithium polymer 10440 batteries are substituted in to do the job.

The build shows that with clever parts selection and some easy hand soldering, you too can build an incredibly dangerous laser pointer at home, that fits neatly in your shirt pocket. Alternatively, you might prefer something on the larger scale. Video after the break.

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Text Projector With — You Know — Lasers

We missed [iliasam’s] laser text projector when it first appeared, perhaps because the original article was in Russian. However, he recently reposted in English and it really caught our eye. You can see a short video of it in operation, below.

The projector uses raster scanning where the beam goes over each spot in a grid pattern. The design uses one laser from a cheap laser pointer and a salvaged mirror module from an old laser printer. The laser pointer diode turned out to be a bit weak, so a DVD laser was eventually put into service. A DVD motor also provides the vertical scan which is just a slight wobble of a mirror. A Blue Pill CPU provides all the smarts. You can find the code on GitHub.

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Creating Coherent Sound Beams, Easily

Lasers work by emitting light that is “coherent” in that it doesn’t spread out in a disorganized way like light from most sources does. This makes extremely focused beams possible that can do things like measure the distance from the Earth to the Moon. This behavior isn’t just limited to electromagnetic waves, though. [Gigs] via [CodeParade] was able to build a device that produces a tightly focused sound wave, essentially building an audio laser.

Curiously enough, the device does not emit sound in the frequency range of human hearing. It uses a set of ultrasound speakers which emit a “carrier wave” in the ultrasound frequency. However, with a relatively simple circuit a second signal in the audible frequency range is modulated on top of it, much the same way that an AM radio broadcast has a carrier wave with an amplitude modulated signal on top of it. With this device, though, the air itself acts in a nonlinear way and demodulates the signal, producing the modulated signal as audible sounds.

There are some interesting effects of using this device. First, it is extremely directional, so in order to hear sound from the device you would need to be standing directly in front of it. However, once the ultrasound beam hits a solid object, the wave is instantly demodulated and reflected from the object, making it sound like that object is making the sounds and not the device. It’s obvious that this effect is hard to experience via video, but it’s interesting enough that we’d like to have one of our own to try out. It’s not the only time that sound waves and electromagnetic waves have paired up in interesting ways, either.

Thanks to [Setvir] for the tip! Continue reading “Creating Coherent Sound Beams, Easily”

Laser Light Show Turned Into Graphical Equalizer

The gold standard for laser light shows during rock concerts is Pink Floyd, with shows famous for visual effects as well as excellent music. Not all of us have the funding necessary to produce such epic tapestries of light and sound, but with a little bit of hardware we can get something close. [James]’s latest project is along these lines: he recently built a laser light graphical equalizer that can be used when his band is playing gigs.

To create the laser lines for the equalizer bands, [James] used a series of mirrors mounted on a spinning shaft. When a laser is projected on the spinning mirrors it creates a line. From there, he needed a way to manage the height of each of the seven lines. He used a series of shrouds with servo motors which can shutter the laser lines to their appropriate height.

The final part of the project came in getting the programming done. The brain of this project is an MSGEQ7 which  takes an audio input signal and splits it into seven frequencies for the equalizer. Each one of the seven frequencies is fed to one of the seven servo-controlled shutters which controls the height of each laser line using an Arduino. This is a great project, and [James] is perhaps well on his way to using lasers for other interesting musical purposes.

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