Contagious Ideas

March 29, 2025 by Elliot Williams 10 Comments

We ran a story about a wall-mounted plotter bot this week, Mural. It’s a simple, but very well implemented, take on a theme that we’ve seen over and over again in various forms. Two lines, or in this case timing belts, hang the bot on a wall, and two motors drive it around. Maybe a servo pulls the pen in and out, but that’s about it. The rest is motor driving and code.

We were thinking about the first such bot we’ve ever seen, and couldn’t come up with anything earlier than Hektor, a spray-painting version of this idea by [Juerg Lehni]. And since then, it’s reappeared in numerous variations.

Some implementations mount the motors on the wall, some on the bot. There are various geometries and refinements to try to make the system behave more like a simple Cartesian one, but in the end, you always have to deal with a little bit of geometry, or just relish the not-quite-straight lines. (We have yet to see an implementation that maps out the nonlinearities using a webcam, for instance, but that would be cool.) If you’re feeling particularly reductionist, you can even do away with the pen-lifter entirely and simply draw everything as a connected line, Etch-a-Sketch style. Maslow CNC swaps out the pen for a router, and cuts wood.

What I love about this family of wall-plotter bots is that none of them are identical, but they all clearly share the same fundamental idea. You certainly wouldn’t call any one of them a “copy” of another, but they’re all related, like riffing off of the same piece of music, or painting the same haystack in different lighting conditions: robot jazz, or a study in various mechanical implementations of the same core concept. The collection of all wall bots is more than the sum of its parts, and you can learn something from each one. Have you made yours yet?

(Fantastic plotter-bot art by [Sarah Petkus] from her write-up ten years ago!)

Your Badminton Racket Needs Restringing? There’s A DIY Machine For That

March 27, 2025 by Elliot Williams 4 Comments

We don’t often get our badminton rackets restrung, but if we did, [kuokuo702]’s PicoBETH project would be where we’d turn. This is a neat machine build for a very niche application, but it’s also a nicely elaborated project with motors, load cells, and even a sweet knobby-patterned faceplate that is certainly worth a look even if you’re not doing your own restringing.

We’ll admit that everything we know about restringing rackets we learned by watching [kuokuo]’s demo video, but the basic procedure goes like this: you zigzag the string through the holes in the racket, controlling the tension at each stage along the way. A professional racket frame and clamp hold the tension constant while you fiddle the string through the next hole, but getting the tension just right in the first place is the job of [kuokuo]’s machine. It does this with a load cell, stepper motor, and ball screw, all under microcontroller control. Pull the string through, let the machine tension it, clamp it down, and then move on to the next row.

Automating the tension head allows [kuokuo] to do some fancy tricks, like pre-stretching the strings and even logging the tension in the string at each step along the way. The firmware has an extensive self-calibration procedure, and in all seems to be very professional. But it’s not simply functional; it also has a fun LEGO-compatible collection of bumps integrated into the 3D-printed dust cover. That way, your minifigs can watch you at work? Why not!

Automating random chores is a great excuse to build fun little machines, and in that vein, we salute [kuokuo]’s endeavor. Once you start, you’ll find stepper motors sprouting all around like crocuses in a spring field. And speaking of spring, Easter is just around the corner. So if you don’t play badminton, maybe it’s time to build yourself an eggbot.

Continue reading “Your Badminton Racket Needs Restringing? There’s A DIY Machine For That” →

Supercon 2024: Killing Mosquitoes With Freaking Drones, And Sonar

March 25, 2025 by Elliot Williams 52 Comments

Suppose that you want to get rid of a whole lot of mosquitoes with a quadcopter drone by chopping them up in the rotor blades. If you had really good eyesight and pretty amazing piloting skills, you could maybe fly the drone yourself, but honestly this looks like it should be automated. [Alex Toussaint] took us on a tour of how far he has gotten toward that goal in his amazingly broad-ranging 2024 Superconference talk. (Embedded below.)

The end result is an amazing 380-element phased sonar array that allows him to detect the location of mosquitoes in mid-air, identifying them by their particular micro-doppler return signature. It’s an amazing gadget called LeSonar2, that he has open-sourced, and that doubtless has many other applications at the tweak of an algorithm.

Rolling back in time a little bit, the talk starts off with [Alex]’s thoughts about self-guiding drones in general. For obstacle avoidance, you might think of using a camera, but they can be heavy and require a lot of expensive computation. [Alex] favored ultrasonic range finding. But then an array of ultrasonic range finders could locate smaller objects and more precisely than the single ranger that you probably have in mind. This got [Alex] into beamforming and he built an early prototype, which we’ve actually covered in the past. If you’re into this sort of thing, the talk contains a very nice description of the necessary DSP.

[Alex]’s big breakthrough, though, came with shrinking down the ultrasonic receivers. The angular resolution that you can resolve with a beam-forming array is limited by the distance between the microphone elements, and traditional ultrasonic devices like we use in cars are kinda bulky. So here comes a hack: the TDK T3902 MEMS microphones work just fine up into the ultrasound range, even though they’re designed for human hearing. Combining 380 of these in a very tightly packed array, and pushing all of their parallel data into an FPGA for computation, lead to the LeSonar2. Bigger transducers put out ultrasound pulses, the FPGA does some very intense filtering and combining of the output of each microphone, and the resulting 3D range data is sent out over USB.

After a marvelous demo of the device, we get to the end-game application: finding and identifying mosquitoes in mid-air. If you don’t want to kill flies, wasps, bees, or other useful pollinators while eradicating the tiny little bloodsuckers that are the drone’s target, you need to be able to not only locate bugs, but discriminate mosquitoes from the others.

For this, he uses the micro-doppler signatures that the different wing beats of the various insects put out. Wasps have a very wide-band doppler echo – their relatively long and thin wings are moving slower at the roots than at the tips. Flies, on the other hand, have stubbier wings, and emit a tighter echo signal. The mosquito signal is even tighter.

If you told us that you could use sonar to detect mosquitoes at a distance of a few meters, much less locate them and differentiate them from their other insect brethren, we would have thought that it was impossible. But [Alex] and his team are building these devices, and you can even build one yourself if you want. So watch the talk, learn about phased arrays, and start daydreaming about what you would use something like this for.

Continue reading “Supercon 2024: Killing Mosquitoes With Freaking Drones, And Sonar” →

“Unnecessary” Automation Of A DIY Star Lamp Build

March 23, 2025 by Elliot Williams 10 Comments

It all started with a gift idea: a star-field lamp in the form of a concrete sphere with lightpipes poking out where the stars are, lit up from the inside by LEDs. When you’re making one of these, maybe-just-maybe you’d be willing to drill a thousand holes and fit a thousand little plastic rods, but by the time you’re making a second, it’s time to build a machine to do the work for you.

So maybe we quibble with the channel name “Unnecessary Automation,” but we won’t quibble with the results. It’s a machine that orients a sphere, drills the hole, inserts the plastic wire, glues it together with a UV-curing glue, and then trims the end off. And if you like crazy machines, it’s a beauty.

The video goes through all of the design thoughts in detail, but it’s when it comes time to build the machine that the extra-clever bits emerge. For instance, [UA] used a custom 3D-printed peristaltic pump to push the glue out. Taking the disadvantage of peristaltic pumps – that they pulse – as an advantage, a custom housing was designed that dispensed the right amount between the rollers. The rolling glue dispenser mechanism tips up and back to prevent drips.

There are tons of other project-specific hacks here, from the form on the inside of the sphere that simplifies optic bundling and routing to the clever use of a razor blade as a spring. Give it a watch if you find yourself designing your own wacky machines. We think Rube Goldberg would approve. Check out this video for a more software-orientated take on fiber-optic displays.

Continue reading ““Unnecessary” Automation Of A DIY Star Lamp Build” →

Building The Simplest Atomic Force Microscope

March 23, 2025 by Elliot Williams 23 Comments

Doing it yourself may not get you the most precise lab equipment in the world, but it gets you a hands-on appreciation of the techniques that just can’t be beat. Today’s example of this adage: [Stoppi] built an atomic force microscope out of mostly junk parts and got pretty good results, considering. (Original is in German; read it translated here.)

The traditional AFM setup uses a piezo micromotor to raise and lower the sample into a very, very fine point. When this point deflects, it reads the height from the piezo setup and a motor stage moves on to the next point. Resolution is essentially limited by how fine a point you can make and how precisely you can read from the motion stages. Here, [stoppi]’s motion stage follows the traditional hacker avenue of twin DVD sleds, but instead of a piezo motor, he bounces a laser off of a mirror on top of the point and reads the deflection with a line sensor. It’s a clever and much simpler solution.

A lot of the learnings here are in the machine build. Custom nichrome and tungsten tips are abandoned in favor of a presumably steel compass tip. The first-draft spring ended up wobbling in the X and Y directions, rather than just moving in the desired Z, so that mechanism got reinforced with aluminum blocks. And finally, the line sensors were easily swamped by the laser’s brightness, so neutral density filters were added to the project.

The result? A nice side effect of the laser-bouncing-off-of-mirror setup is that the minimum resolvable height can be increased simply by moving the line sensors further and further away from the sample, multiplying the deflection by the baseline. Across his kitchen, [stoppi] is easily able to resolve the 35-um height of a PCB’s copper pour. Not bad for junk bin parts, a point from a crafts store, and a line sensor.

If you want to know how far you can push a home ~~AFM~~ microscope project, check out [Dan Berard]’s absolutely classic hack. And once you have microscope images of every individual atom in the house, you’ll, of course, want to print them out.

Generative Art Machine Does It One Euro At A Time

March 22, 2025 by Elliot Williams 14 Comments

[Niklas Roy] obviously had a great time building this generative art cabinet that puts you in the role of the curator – ever-changing images show on the screen, but it’s only when you put your money in that it prints yours out, stamps it for authenticity, and cuts it off the paper roll with a mechanical box cutter.

If you like fun machines, you should absolutely go check out the video, embedded below. The LCD screen has been stripped of its backlight, allowing you to verify that the plot exactly matches the screen by staring through it. The screen flashes red for a sec, and your art is then dispensed. It’s lovely mechatronic theater. We also dig the “progress bar” that is represented by how much of your one Euro’s worth of art it has plotted so far. And it seems to track perfectly; Bill Gates could learn something from watching this. Be sure to check out the build log to see how it all came together.

You’d be forgiven if you expected some AI to be behind the scenes these days, but the algorithm is custom designed by [Niklas] himself, ironically adding to the sense of humanity behind it all. It takes the Unix epoch timestamp as the seed to generate a whole bunch of points, then it connects them together. Each piece is unique, but of course it’s also reproducible, given the timestamp. We’re not sure where this all lies in the current debates about authenticity and ownership of art, but that’s for the comment section.

If you want to see more of [Niklas]’s work, well this isn’t the first time his contraptions have graced our pages. But just last weekend at Hackaday Europe was the first time that he’s ever given us a talk, and it’s entertaining and beautiful. Go check that out next. Continue reading “Generative Art Machine Does It One Euro At A Time” →

Thanks For Hackaday Europe!

March 22, 2025 by Elliot Williams 10 Comments

We just got back from Hackaday Europe last weekend, and we’re still coming down off the high. It was great to be surrounded by so many crazy, bright, and crazy-bright folks all sharing what they are pouring their creative energy into. The talks were great, and the discussions and impromptu collaborations have added dramatically to our stack of to-do projects. (Thanks?) Badges were hacked, stories were shared, and a good time was had by all.

At the event, we were approached by someone who wanted to know if we could replicate something like Hackaday Europe in a different location, one where there just isn’t as vibrant a hacking scene. And the answer, of course, was maybe, but probably not.

It’s not that we don’t try to put on a good show, bring along fun schwag, and schedule up a nice location. But it’s the crowd of people who attend who make a Hackaday event a Hackaday event. Without you all, it just wouldn’t work.

So in that spirit, thanks to everyone who attended, and who brought along their passions and projects! It was great to see you all, and we’ll do it again soon.