Laser-Etch Stainless with Only Plaster & Alcohol

Many hobbyists and hackerspaces have the $500 Chinese 40W lasercutters which most of us know are about as successful at etching metals as a featherduster is at drilling. [Frankie] and [Bryan] have figured out a way to use the laser to chemically activate an etching process. See experiment part 2 as well.

First, to be clear, they are using a quality 40W Epilog Zing, not the cheap one, but40W is40W. They mixed the plaster (calcium sulfate) with Isopropyl until it resembled white ketchup. After either thinly painting or airbrushing the material onto the stainless surface (both worked), the mixture is dried with a heatgun then put into the laser. 100% power and 5% speed was what worked for them.

The result was an engrave with a noticeable bite. Something they claim had no effect at all without the mixture.

Stainless steel is an alloy of iron and some chromium – not the same as chrome-plated steel. [Frankie]’s explanation of the chemistry is that the surface layer of the stainless is a transparent chromium oxide. With the heat of the laser, the calcium and chromium swap dance partners. Calcium takes the oxygen and chromium takes the sulfate. The calcium oxide washes off but the chromium sulfate causes the etch.

Next time you’re at your local space, give this a try.

Drawing On Glow In The Dark Surfaces With Lasers

What do you get when you have a computer-controlled laser pointer and a big sheet of glow in the dark material? Something very cool, apparently. [Riley] put together a great build that goes far beyond a simple laser diode and servo build. He’s using stepper motors and a proper motion control software for this one.

The theory behind the device is simple – point a laser at some glow in the dark surface – but [Riley] is doing this project right. Instead of jittery servos, the X and Y axes of the laser pointer are stepper motors. These are controlled by an Arduino Due and TinyG motion control software. This isn’t [Riley]’s first rodeo with TinyG; we saw him at Maker Faire NYC with a pendulum demonstration that was absolutely phenomenal.

Right now, [Riley] is taking SVG images, converting them to Gcode, and putting them up on some glow in the dark vinyl. Since the Hackaday Skull ‘n Wrenches is available in SVG format, that was an easy call to make on what to display in weird phosphorescent green. You can see a video of that along with a few others below.

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Using Lasers for Hair Growth

HowToLou is back with a rather interesting build: One hundred laser diodes for hair growth.

Before you guffaw at the idea of lasers regrowing hair lost to male pattern baldness, there’s a surprising amount of FDA documents covering the use of laser diodes and red LEDs for hair growth and an interesting study covering teeth regrowth with lasers. Yes folks, it’s a real thing, but something that will never get a double-blind study for obvious reasons.

[Lou] is building his hat with 100 laser diodes, most of which were sourced from Amazon. These diodes were implanted in a piece of foam flooring, a rather interesting solution that puts dozens of diodes in a flexible module that’s pretty good for making a wearable device.

The lasers are powered by three AA batteries, stuffed into a four-slot battery holder that was modified to accommodate a power switch. [Lou] has been wearing a nine-diode hat for a month now, and if the pictures are to be believed, he is seeing a little bit of hair growth. At the very least, it’s an interesting pseudo-medical build that seems to be producing results.

Hats like these are commercially available for about $700. [Lou] built his for about $60. We’re calling that a win even if it doesn’t end up working to [Lou]’s satisfaction. Just don’t look at the lasers with your remaining eye.

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MIDI Keyboard with Frickin’ Laser Keys

MIDI instruments are cool, but they’re not laser cool. That is, unless you’ve added lasers to your MIDI instrument like [Lasse].

[Lasse] started out with an old MIDI keyboard. The plan was to recycle an older keyboard rather than have to purchase something new. In this case, the team used an ESi Keycontrol 49. They keyboard was torn apart to get to the creamy center circuit boards. [Lasse] says that most MIDI keyboards come withe a MIDI controller board and the actual key control board.

Once the key controller board was identified, [Lasse] needed to figure out how to actually trigger the keys without the physical keyboard in place. He did this by shorting out different pads while the keyboard was hooked up to the computer. If he hit the correct pads, a note would play. Simple, but effective.

The housing for the project is made out of wood. Holes were drilled in one piece to mount 12 laser diodes. That number is not arbitrary. Those familiar with music theory will know that there are 12 notes in an octave. The lasers were powered via the 5V source from USB. The lasers were then aimed at another piece of wood.

Holes were drilled in this second piece wherever the lasers hit. Simple photo resistors were mounted here. The only other components needed for each laser sensor were a resistor and a transistor. This simple discreet circuit is enough to simulate a key press when the laser beam is broken. No programming or microcontrollers required. Check out the demonstration video below to see how it works. Continue reading “MIDI Keyboard with Frickin’ Laser Keys”

Doing Unsafe Things With A Laser Watch

[Pierce Brosnan]-era James Bond had a beautiful Omega wristwatch. Of course as with any Bond gadget, it couldn’t just tell time; it needed to do something else. This watch had a laser, and [Patrick] figured he could replicate this build.

This is apretty normal 1.5W laser diode build, stuffed into a wrist-mountable device that will kill balloons. This is really a watch, though: press a button and this thing will tell time.

In the video below, [Patrick] goes over what damage this watch can do. He manages to pop some black balloons, burn holes in a CD case, light a few matches, cut cellotape, and put tiny burn marks in his wall. The battery won’t last long – just a few minutes – but more than enough to propel [Patrick] into Youtube stardom.

There are no plans or tutorials for the build, but the teardown [Patrick] shows is pretty impressive. To stuff a laser diode, battery, and clock into a watch-sized compartment, [Patrick] needed to turn down the metal buttons to fit everything into his watch case.

Because the comments for this post will invariable fill up with concern trolls, we’re just going to say, yes, this is incredibly unsafe, no one should ever do this, and it probably kills puppies.


Automated CAD Design for Enclosures

[Jon] a.k.a. [Pedantite] recently added small-scale laser cutting to his business and thought about using that laser cutter to add some value to some of the many project designs he creates. Yes, this means custom laser cut enclosures, but how to go about it? [Jon] loves automation, and that can only mean automated design of laser cut enclosures by reading the board files from his project library.

The idea of automating the design of plastic enclosures was to read the design files, figure out the dimensions of the board and where the mounting holes go, and generate a file for the laser cutter. The weapon of choice was OpenSCAD, a design language that can be highly parameterized, read external design files, and spit out proper DXF files for laser cutting.

[Jon] set up his toolchain as a Python script that reads design files, sends parameters off to a .SCAD file, and generates a DXF for the laser cutter. There’s also a bit that generates enough data for Blender to render a 3D image of the finished product, all only from gerbers, a drill file, and a few user variables.

The source for these files haven’t been released yet, but that’s only because it’s in a proof-of-concept stage right now. You can check out an example of a render of one of the cases below.

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How a Real 3D Display Works

There’s a new display technique that’s making the blog rounds, and like anything that seems like its torn from [George Lucas]’ cutting room floor, it’s getting a lot of attention. It’s a device that can display voxels in midair, forming low-resolution three-dimensional patterns without any screen, any fog machine, or any reflective medium. It’s really the closest thing to the projectors in a holodeck we’ve seen yet, leading a few people to ask how it’s done.

This isn’t the first time we’ve seen something like this. A few years ago. a similar 3D display technology was demonstrated that used a green laser to display tens of thousands of voxels in a display medium. The same company used this technology to draw white voxels in air, without a smoke machine or anything else for the laser beam to reflect off of. We couldn’t grasp how this worked at the time, but with a little bit of research we can find the relevant documentation.

A system like this was first published in 2006, built upon earlier work that only displayed pixels on a 2D plane. The device worked by taking an infrared Nd:YAG laser, and focusing the beam to an extremely small point. At that point, the atmosphere heats up enough to turn into plasma and turns into a bright, if temporary, point of light. With the laser pulsing several hundred times a second, a picture can be built up with these small plasma bursts.


Moving a ball of plasma around in 2D space is rather easy; all you need are a few mirrors. To get a third dimension to projected 3D images, a lens mounted on a linear rail moves back and forth changing the focal length of the optics setup. It’s an extremely impressive optical setup, but simple enough to get the jist of.

Having a device that projects images with balls of plasma leads to another question: how safe is this thing? There’s no mention of how powerful the laser used in this device is, but in every picture of this projector, people are wearing goggles. In the videos – one is available below – there is something that is obviously missing once you notice it: sound. This projector is creating tiny balls of expanding air hundreds of times per second. We don’t know what it sounds like – or if you can hear it at all – but a constant buzz would limit its application as an advertising medium.

As with any state-of-the-art project where we kinda know how it works, there’s a good chance someone with experience in optics could put something like this together. A normal green laser pointer in a water medium would be much safer than an IR YAG laser, but other than that the door is wide open for a replication of this project.

Thanks [Sean] for sending this in.

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