Tiny Plotter Is Made Of Strings And Cardboard

October 4, 2018 by Tom Nardi 14 Comments

If you’ve been hanging around Hackaday for any length of time, you’ve undoubtedly seen the work of [Niklas Roy]. A prolific maker of…everything, we’ve covered his projects for over a decade now. He’s one of an elite group of hackers who can say they’ve been around since Hackaday was still using black & white pictures. Yet sometimes projects fall through the cracks.

Thanks to a tip sent in from one of our beloved readers, we’re just now seeing this incredible cardboard plotter [Niklas] made for a workshop he ran at the University of Art and Design Offenbach several years ago. The fully manual machine is controlled with two rotary dials and a switch, and it even comes with a book that allows you to “program” it by dialing in specific sequences of numbers.

Not that it detracts from the project, but its worth mentioning that the “cardboard” [Niklas] used is what is known as Finnboard, a thin construction material made of wood pulp that looks similar to balsa sheets. The material is easy to work with and much stronger than what we’d traditionally think of as cardboard. Beyond the Finnboard, the plotter uses welding rods as axles and slide rails, with glue, tape, and string holding it all together.

The dials on the control panel correspond to the X and Y axes: turning the X axis dial moves the bed forward and backward, and the Y dial moves the pen left and right. The switch above the dial lowers and raises the pen so it comes into contact with the paper below. With coordination between these three inputs, the operator can either draw “freehand” or follow the sequences listed in the “Code Book” to recreate stored drawings and messages.

Believe it or not, this isn’t the first time we’ve seen somebody made a plotter out of cardboard. Though previous entries into this specific niche did use servos to move around.

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Bot Makes Etch A Sketch Art In One Continuous Line

September 28, 2018 by Dan Maloney 17 Comments

Introduced in 1960 for the princely sum of $2.99 ($25.00 today), Etch A Sketch was to become a standard issue item for the Baby Boomers’ toy box. As enchanting as the toy seems, it’s hard to see why it had staying power: it was hard for young fingers to twirl the knobs, diagonal lines and smooth curves required a concert pianist’s fine motor control, and whatever drawings we managed to make were erased at the slightest jostle of the tablet.

Intent on righting these wrongs, [Sunny Balasubramanian] not only motorized an Etch A Sketch, but he’s also given it a mind of its own in a way. For those unfamiliar with the toy, it’s basically a manual X-Y plotter that drags a stylus across the underside of a glass screen, scraping off a silver powder clinging to the glass to make dark lines. Replacing the knobs with steppers is straightforward, of course, but driving them is the trick. [Sunny] hooked his up to a Raspberry Pi and wrote some Python code to drive them. The Pi also accepts input image files and processes them for rendering through the plotter, first doing Canny edge detection in OpenCV, then plotting a single path through the largest collection of connected pixels in the image. From there it’s just a matter of spinning the motors to create surprisingly detailed images. Check out the short video below to see it in action.

It’s hardly the first automatic Etch A Sketch we’ve seen – here’s one that automates everything including the shake to erase the drawing. That one cheats a little though, in that it rasters across the screen like a CRT. We really like how this one just does a single path. Pretty clever.

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Sorting LEGO Is Like Making A Box Of Chocolates

September 27, 2018 by Steven Dufresne 6 Comments

Did you know that chocolate candy production and sorting LEGO bricks have something in common? They both use the same techniques for turning clumps of chocolates or bricks into individual ones moving down a conveyor belt. At least that’s what [Paco Garcia] found out when making his LEGO Sorter.

However, he didn’t find that out right away. He first experimented with his own techniques, learning that if he fed bricks to his conveyor belt by dropping a batch of them in a line perpendicular to the direction of belt travel then no subsequent separation attempt of his worked. He then turned to [akiyuky’s] LEGO sorter for inspiration and dropped them onto the belt at an angle, ensuring that some bricks would be in front of others. A further trick he found is very well demonstrated in the chocolate sorting video below and shown in the image here. That is to use guides on the belt which serve to create speed differentials. Bricks move slower than the conveyor belt while pressed against a guide but when a brick leaves the guide, it accelerates to the speed of the conveyor belt, pulling away from the bricks still at the guide and thus separating them.

A further discovery had nothing to do with chocolate production, unless maybe for quality control. Once an individual brick had been separated out, it had to be classified. To do that he used Google’s Inception v3 neural network. But first, he had to retrain it for recognizing different types of LEGO bricks, something we’ve seen done before for use with recognizing playing cards. And to do the retraining, he needed many images of different bricks all separated into their different types. That’s where he came up with a clever trick. He used his own sorter for that. For example, to get a bunch of images of 1×1 bricks of different colors and orientations, he simply ran them through the sorter, saving the images to files and assigning them to the 1×1 brick class. He then used his desktop machine with a GeForce GT 730 GPU for the retraining, taking around 2.7 seconds per brick. For sorting though, he runs the trained neural network on a Raspberry Pi, taking 3.8 seconds for each brick. The resulting sorter works quite well, sorting with 89% accuracy. Watch it in action in the video below.
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A Nibble And A Half Of Wooden Bits

September 25, 2018 by Brian McEvoy 8 Comments

If you are familiar with binary, what would you need to teach someone who only knows decimal? If you do not know how to count in binary, let us know if the video below the break helps you understand how the base-2 number system works. If learning or counting binary is not what you are interested in, maybe you can appreciate the mechanics involved with making a counter that cycles through all the ones and zeros (links to the video shown below). The mechanism is simple enough. A lever at the corner of each “1” panel is attached off-center, so it hangs when it is upside-down, then falls to the side when it is upright, so it can swivel the adjacent panel.

Perhaps this is a desktop bauble to show off your adeptness at carpentry, or skills with a laser cutter, or 3D printer. No matter what it is made out of, it will not help you get any work done unless you are a teacher who wants to demonstrate the discrete nature of binary. If wood and bits are up your alley, we have a gorgeous binary driftwood clock to feast your eyes on. Meanwhile if analog methods of working digital numbers suit you, we have binary math performed with paper models.

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Self-Solving Rubik’s Cube

September 24, 2018 by Dan Maloney 48 Comments

Rubik’s Cube has been around for what seems like forever now, and has spawned an entire subculture devoted to solving the puzzle with automation. Most Rubik robots put the cube in a specially designed cradle bristling with actuators and sensors, and while those rigs are impressive, they don’t come close to this robotic Rubik solver built into the cube itself.

Fair warning that [Human Controller] doesn’t provide much detail on this build other than pictures; even translating the Japanese web page doesn’t offer much more information. But there are pictures, plus the video below, which reveal the engineering masterpiece encased within the standard sized Rubik’s cube. The internal mechanism of the original cube had been replaced by a spherical assembly around which the cube’s faces rotate. The sphere, which appears to be 3D-printed, houses six motors and gear trains, along with a microcontroller board and what appear to be Hall sensor boards to detect the position of each face. Everything is wired up with magnet wire to keep bundles to a minimum size, and buried deep inside is a LiPo battery pack. A disassembly video offers further clues to this ingenious device’s inner workings.

Once the cube senses that it has been scrambled, it sets to work on the solution, walking all over the table in the process. It’s clearly not just recording the scrambling steps and playing them back in reverse; the video below shows far more moves to solve the cube than the 15 it took to scramble it.

While we’re always impressed by marvels of speed like this robot with a 637 millisecond solve time, putting everything needed to solve the cube inside it is a feat worth celebrating. Here’s hoping that a build log shows up soon to satisfy our need for details.

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This TARDIS Is Bigger On The Inside

September 21, 2018 by Rich Hawkes 24 Comments

A few months ago, YouTube user [Maladroit Modeller] uploaded a video of his model TARDIS from Doctor Who which shows an inside that’s bigger than the outside. Recently, [Maladroit Modeller] posted some pictures and has now uploaded a video showing how it’s done.

The TARDIS model itself is a 3:75 scale “Spin & Fly” model. The case to show everything off is built from foam core and the interior is built from foam core, silver paper, cardboard, styrene and other bits and pieces. There looks like there’s some EL wire being used, too, along with a lot of LEDs.

The build looks great and the illusion works very nicely in the video. Check out the video after the break, and then check out the “how it’s done” video for an explanation. Continue reading “This TARDIS Is Bigger On The Inside” →

Cheap RC Boat Turned Weirdly Capable Seaplane

September 9, 2018 by Tom Nardi 8 Comments

What do you get when you combine a cheap RC boat from Walmart, foam board, a couple powerful motors, and some aluminum cans? Most people would just end up with a pile of garbage, but we’ve already established [Peter Sripol] is fairly far from “most people”. In his hands, this collection of scraps turns into an almost unbelievably nimble seaplane, despite looking like something out of a TailSpin and Mad Max crossover episode.

In his latest YouTube video, [Peter] takes viewers through the process of turning one of these rather lame RC boats into an impressive flying machine. His took inspiration from the Sikorsky S-38, an American amphibious aircraft introduced in 1928. The S-38 looked like a fairly traditional boat bolted to the bottom of a set of huge wings, so it’s little surprise that he patterned this build after it.

The construction of the seaplane is very simple, and boils down to cutting some big wings out of foam board, using some sticks to give it some rigid framing, and putting a tail on it. The biggest problem is that the boat’s hull lacks the “steps” that a seaplane would have, so it’s not an ideal shape to lift out of the water. But with enough thrust and a big enough control surface, it all works out in the end.

Which is in effect the principle by which the whole plane flies. There’s a large elevator cantilevered far astern to help leverage the boat out of the water, but otherwise all other control is provided by differential thrust between the two top mounted motors. The lack of a rudder does make its handling a bit sluggish in the water, but it obviously has no problem once it’s airborne.

If [Peter] and his foam board artistry seem familiar, it’s probably from the not one but two homemade aircraft he built with shockingly similar techniques to this current project.

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