Tales Of Garage Design: Achieving Precision From Imprecise Parts

April 12, 2016 by Sonya Vasquez 48 Comments

Designing parts to fit perfectly together is hard. Whether it’s the coarseness of our fabrication tools or the procedures of the vendor who makes our parts, parts are rarely the exact dimension that we wish they were. Sadly, this is the penalty that we pay by living in a real world: none of our procedures (or even our measurement tools!) are perfect. In a world of imperfect parts, imperfect procedures, and imperfect measurement techniques, how on earth are we supposed to build anything that works? Fortunately, we’re in luck! From the brooding minds of past engineers, comes a suite of design techniques that can combat the imperfections of living in an erroneous world.

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Take The Long Road To A Precise Laser PCB Exposer

April 6, 2016 by Gerrit Coetzee 23 Comments

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.
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Smartphone And IR Line Laser Measure Distance

April 4, 2016 by Rud Merriam 12 Comments

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.

Testing smartphone and XV-11 lidars

Range for smartphone and XV-11 lidars outdoors.

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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DIY Vacuum Table Makes Lasering Even Easier

March 19, 2016 by James Hobson 13 Comments

If you’ve ever tried to laser flexible rolls of material you’ll know it can be really annoying to setup in the laser cutter.

Most of the time we use magnets, but then you have to make sure the magnets are clear of the work path — and then you end up wasting extra material… It’d be amazing to have a vacuum table that just sucks down your work piece to keep it in place! As it turns out, it’s not that hard to make!

After getting frustrated lasering warped material themselves, [Martin Raynsford] and the gang decided to make their very own vacuum table — using a laser cutter of course. Continue reading “DIY Vacuum Table Makes Lasering Even Easier” →

Laser Removes Rust Like Magic

March 17, 2016 by Jenny List 112 Comments

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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The Wonderful Scent Of Etching Pi On Pie For Pi Day

March 15, 2016 by Sonya Vasquez 15 Comments

My “owl-hours” these last few months have been buried in the garage, chopping down aluminum extrusions for a homebrew laser cutter. Nevertheless, it’s time-well-spent. With the skeleton of the gantry now in place, what better way to give it a test-run other than engraving a few sweets?

(Goggles on, folks!)

Yesterday marked this year’s Pi Day, a time to commemorate our commitment to nerdom. I’m no baker; so when a couple friends put me to work on the assembly line of Pi-day pie-making, I couldn’t resist giving one a special touch.

This beloved journey towards building a laser cutter isn’t quite done, but it’s well on its way! Without fumigation, my only exceptions for cutting materials at this stage are paper, and food that smells great after burning it.

Without further ado, I’m honored to serve up a few digits of Pi-on-Pie.

To make the pattern, I generated a DXF vector file with Solidworks, and produced GCode with dxf2gcode. Admittedly, I wholeheartedly believe that this job better lends itself to GCMC, the open source GCode Metacompiler; but, sadly, time was against me. My only true regret: no raspberries in this pipeline.

From Wii-Motes to 3D sintered objects, we’ve seen some bizarre and fantastic objects enter and exit the hood of many laser cutters. If you’ve got a tale behind your build, we’d love to hear about some of your adventures. Join us on the IO and tell us your story as it happens!

(Ok, goggles off.)

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Aligning Invisible Lasers On-the-cheap

March 10, 2016 by Sonya Vasquez 29 Comments

Lining up the beam from your homebrew (or retrofitted) laser cutter doesn’t come without its challenges. For instance, how do I use my remaining eye to align an invisible beam that has enough power to burn through some objects in its path? Some of us will go through the extra hassle and expense of mixing in a visible guide that traces the path of the CO2 laser. For the penny-pinchers out there, though, [Stephen] has us covered with an inexpensive technique that will cut you down by only a few strips of masking tape.

Stephan’s technique is simple, but elegant. He covers each mirror with tape, fires the laser, and leaves a burn mark, working his way from the last mirror that the laser hits to the first. With a burn mark on each mirror, and one through a guide made from a sheet of plywood, [Stephen] has a pretty good idea where the native direction of the beam is headed. He then swaps a red dot laser in to line up with the burn marks, and then aligns the mirrors using visible, and safe, light. Phew! Now that’s a lot easier than iteratively firing the beam and replacing the tape on the mirror each time we want to tweak the mirror alignment.

With all that burnt masking tape, the process can get a bit smelly. Nevertheless, we’ve filed this one away for later when we start getting that itching, burning sensation that kicks us into building our own homebrew laser cutter.

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