A Low-Cost Mini PCB Printer

The next great advancement in homebrew electronics is an easy way to turn copper clad board into functional circuit boards. This has been done since the 60s with etch resist pens, sheets of etch resist rub-on transfers, the ever-popular photocopy and clothes iron, and now with small CNC mills. It’s still a messy, slow, and expensive process. [johnowhitaker] and [esot.eric] are trying to solve the latter of these problems with a mini PCB printer made out of DVD drives.

Playing around with the guts of a DVD drive is something [john] and [eric] have been doing for a while now, and for good reason. There’s a lot of interesting tech in DVD drives, with motors, steppers, and gears able to make very, very accurate and precise movements. Most PCBs aren’t very big, either, so a laser cutter that can only traverse an area a few inches square isn’t that much of a downside in this case.

With a small diode laser mounted to a CNC gantry constructed out of DVD drives, the process of making a PCB is actually pretty simple. First, a slurry of laser printer toner and alcohol is applied to the board. Next, the laser on this PCB printer lases over the traces and copper fills, melting the toner. The board is removed, the excess toner wiped off, and the unwanted copper is melted away. Simple, even if it is a little messy.

Of course this method cannot do plated traces like your favorite Internet-based board house, but this does have a few advantages over any other traditional homebrew method. It’s cheap, since CD and DVD drive mechanisms are pretty much standardized between manufacturers. It’s also easy to add soldermask printing to this build, given that soldermasks can be cured with light. It’s a very cool build, and one that would find a home in thousands of garages and hackerspaces around the world.

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Take the Long Road to a Precise Laser PCB Exposer

According to [diyouware], inside of every HD-DVD player is a gem of laser engineering with the designation of PHR-803T, and it’s just begging to be converted into a PCB exposer. Following along similar hacks which tore the laser diode out of Blu-ray players to expose PCBs, they wanted to use the whole PHR-803T unit without disassembling it, and to try to enable all of its unique features.

They envisioned something simple like a scanner for their machine. Just place the PCB on top of a glass sheet, close the lid, and click print. Unfortunately, moving the laser itself just caused too much vibration. So they switched to an inverted delta robot and named it TwinTeeth. In this design, the laser would stay still and the PCB would move.

What follows next is a seriously impressive journey in reverse engineering and design. The PHR-803T had no data sheet, but a ton of features. For example, it can autofocus, and has three different laser diodes. So many interesting problems were found and solved. For example, the halo from the laser caused the surrounding photoresist to cure. They solved it by adding a glass plate with a UV filtering film on it. Only the most focused point of the laser could punch through.

Another adventure was the autofocus. They wanted to autofocus on all four corners of the board. The PHR-803T was designed to read HD-DVDs so can focus a beam to far below 0.01 mm. They got autofocus working with the UV laser, but couldn’t use it on the PCB without curing the photoresist. So they put a piece of aluminum foil at a known level to start. Then they realized they could use the red or infrared diodes to focus instead. Now they can level the PCB in software, and focus the diode without curing the photoresist.

In the end they have an inverted-delta mini PCB factory. It can produce boards around the size of an Arduino shield with a resolution of 600 DPI. Their machine also has attachments for drilling and solder paste dispensing. Check out the video of it in action.
Continue reading “Take the Long Road to a Precise Laser PCB Exposer”

Smartphone and IR Line Laser Measure Distance

Measuring the distance using lasers is a mainstay of self-driving vehicles and ambitious robotics projects. The fine folks at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) decided to tackle the problem in an innovative way. [Jason H. Gao] and [Li-Shiuan Peh] used an infra-red (IR) line laser and the camera on a smartphone. Their prototype cost only $49 since they used a smartphone that was on hand. The article reports good results using the device outdoors in direct sunlight which is often a challenge for inexpensive lidars.

The line laser creates a horizontal line that is reflected back to the camera on the phone. The vertical position of the laser on the camera image lets the phone calculate the distance by parallax. To bring out a faint laser reflection, the algorithm compares four images – two with the laser on and two with it off – and subtracts the background. Using a smartphone for this is ideal since it automatically adjusts for light level and can easily be upgraded to a newer phone with a better camera later.

This should be a cheap and easily replicable setup. If you make one of these, let us know. If you need something more refined, check out this post on interfacing the Neato vacuum cleaner’s XV-11a lidar with the Raspberry Pi.

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Two-Sided Laser Etching

[Dan Royer] explains a simple method to engrave/etch on both sides of a material. This could be useful when you are trying to build enclosures or boxes which might need markings on both sides. There are two hurdles to overcome when doing this. The first is obviously registration. When you flip your job, you want it re-aligned at a known datum/reference point.

The other is your flip axis. If the object is too symmetric, it’s easy to make a mistake here, resulting in mirrored or rotated markings on the other side. Quite simply, [Dan]’s method consists of creating an additional cutting edge around your engraving/cutting job. This outline is such that it provides the required registration and helps flip the job along the desired axis.

You begin by taping down your work piece on the laser bed. Draw a symmetrical shape around the job you want to create in your Laser Cutter software of choice. The shape needs to have just one axis of symmetry – this rules out squares, rectangles or circles – all of which have multiple axes of symmetry. Adding a single small notch in any of these shapes does the trick. Engrave the back side. Then cut the “outside” outline. Lift the job out and flip it over. Engrave the front side. Cut the actual outline of your job and you’re done.

Obviously, doing all this requires some preparation in software. You need the back engrave layer, the front engrave layer, the job cut outline and the registration cut outline. Use color coded pen settings in a drawing to create these layers and the horizontal / vertical mirror or flip commands. These procedures aren’t groundbreaking, but they simplify and nearly automate a common procedure. If you have additional tricks for using laser cutters, chime in with your comments here.

Laser Removes Rust Like Magic

If you’ve worked with steel or iron, you will be very familiar with rust. You will have an impressive armoury of wire brushes and chemicals to deal with it, and your sandblasting guy is probably in your speed-dial list.

We’ve had more than one Hackaday reader contact us of late with videos showing an apparently miraculous handheld laser unit effortlessly stripping away rust, and leaving a near-perfect surface with little mess. Can it be real, they ask, is it an internet hoax? After all if you have done battle with the dreaded iron oxide you’ll know there is no miracle fix to the problem, however you deal with it there has traditionally been hard work involved.

So after a bit of research, we find CleanLaser, the German company whose products feature in the videos. Quoting their website: “Powerful, very short, rapid and moving laser pulses produce micro-plasma bursts, shockwaves and thermal pressure resulting in sublimation and ejection of the target material”. So yes, it seems they’re real.

The website is at pains to stress the environmental benefits of the devices over comparable sandblasting or similar technologies, but has very little information on their safety. They are available in power ratings from 12W to 1KW which is a hell of a lot of laser power to be projecting, yet the operators seem only to be wearing goggles. Perhaps this comes back to the “Powerful, very short, rapid and moving” bit in the quote above, is there no point source to sear your retina? Laser experts please enlighten us in the comments.

If you work with metal or grew up in a metalworking business, this machine probably has you salivating. Sadly for hackers and makers though it’s probable that it and ones like it will be out of our price range for quite some time. Still, the prospect of a guy with one in an industrial unit appearing in most towns can’t be too far away, and that can only be a good thing

The video shows the machine in action. Rusty fire-grate in, perfect shiny surface out. Perhaps only those of you who have spent many hours with a wire brush will understand.

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Gigabit Ethernet Through the Air

There are a couple of really great things about transmitting data using light as the carrier. It can be focused so that it doesn’t spill all over the neighborhood like radio signals do — giving it both some security against eavesdropping and preventing one signal from stepping on another’s toes. And while you can modulate radio signals up nearly to the carrier frequency, the few gigahertz we normally use for radio just won’t cut it for really high bit rates. Light gets you terahertz.

The Koruza project is an open-source, “inexpensive” system that aims to transmit 1 Gb/sec over distances around 100 meters, using modulated infrared light. The intended use-case is urban building-to-building communication at speeds that would otherwise require laying fiber-optic cables. Indeed, the system piggy-backs on existing fiber-optic equipment to get the job done, but the hard part is aligning the units to get maximum signal from point A to point B.

koruza-spec-info

Koruza does this by including motorized lenses on the 3D-printed chassis. You make a rough alignment with a visible green laser, and then fine-tune the IR beams from a web console where you get immediate feedback on how the received signal strength is changing. Both Koruza boxes have a Raspberry Pi inside and use normal networking for calibration and signal-strength statistics. It’s a really neat system, and it’s fully DIY’able except for the commodity fiber-optic bits.

We’ve always had a soft-spot in our heart for transmitting data over light beams. The Ronja project has been doing so since 2001, and over longer distances, with completely DIY hardware, if at a slower bitrate. And now that Li-Fi seems to be getting traction, we might see an unfocused equivalent running inside our homes.

Thanks [Pavel] for the tip!

Etching PCBs With A 3D Printer

With the coming of very cheap blue laser diodes, PCB fabrication has become increasingly interesting. Instead of making a photoresist, placing it over a piece of pre-sensitized copper clad board, and putting the whole assemblage under a blacklight, it’s possible to put a photomask on a board with a tiny bit of very blue light. All you need is a CNC machine. A 3D printer can be a very precise CNC machine, and when you combine these two ideas together, you can make printed circuit boards with an Ultimaker.

[Geggo] had the idea of attaching a blue laser diode to his Ultimaker to burn a few traces into presensitized copper board. With a 3D printed adapter, he was able to mount the diode and associated electronics right on the extruder body. With a small ring to tighten up the aperture, [geggo] was able to put a 50 micrometer wide dot of light on a piece of copper. The laser is powered directly from the PWM fan output on the printer controller board, allowing this entire mish-mash of cheap electronics to be controlled via G-code.

A few experiments were necessary to determine the correct speeds and power settings, with the best results being 1000 mm per minute at 40 mA. The finished board looks fantastic, and a few minutes after [geggo] was done etching a board, he started using his 3D printer as a printer. It’s a result that is so good, so easy to accomplish, and requires so little effort it makes us wonder why we don’t see more of this.