Poetry in Motion with a Sand-Dispensing Dot Matrix Printer

Hackaday gets results! Reader [John] saw our recent Fail of the Week post about a “sand matrix printer” and decided to share his own version, a sand-dispensing dot matrix printer he built last year.

Granted, [John]’s version is almost the exact opposite of [Vjie Miller]’s failed build, which sought to make depressions in the sand to print characters. [John]’s Sandscript takes a hopper full of dry, clean sand and dispenses small piles from six small servo-controlled nozzles. The hopper is mounted on a wheeled frame, and an optical encoder on one wheel senses forward motion to determine when to open each nozzle. As [John] slowly walks behind and to the side of the cart, a line of verse is slowly drizzled out onto the pavement. See it in action in the video below.

More performance art piece than anything else, we can see how this would be really engaging, with people following along like kids after the [Pied Piper], waiting to find out what the full message is. There’s probably a statement in there about the impermanence of art and the fleeting nature of existence, but we just think it’s a really cool build.

We’ve featured other sand writers before, like this high-resolution draw bot that also dispenses sandy verses, or this literal beach-combing art bot. Guess there’s just something about sand that inspires artists and hackers alike.

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Fail Of The Week: Arduino Sand Matrix Printer

NYC beaches are where tropical beaches addicted to meth go to die. So says [Vije Miller] in his write-up for his Arduino sand matrix printer. It’s a clever idea, five servo-operated cardboard plungers that indent a pattern of dots in the sand as the device is pulled forward, resulting in something not unlike a dot matrix printer that can write messages in the sand.

He’s submitted it to us as a Fail Of The Week, because it doesn’t do a very good job of writing in the sand, and it’s burned out a servo. But we feel this isn’t entirely fair, because whether or not it has delivered the goods it’s still an excellent build. Cardboard isn’t a material we see much of here at Hackaday, but in this case he’s mastered it in a complex mechanism that while it may have proved a little too flexible for the job in hand is nevertheless a rather impressive piece of work.

You can see a brief video below the break showing it in action. He tells us his motivation has waned on this project, and expresses the hope that others will take up the baton and produce a more viable machine.

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Hackaday Prize: An Autonomous Beach Art Robot

Some people find it hard to look at a huge, flat expanse of floor or ground and not see a canvas. From the outfield grass of a baseball park to some poor farmer’s wheat field, trampling, trimming or painting patterns can present an irresistible temptation. But the larger the canvas the more challenging the composition will be, which is where this autonomous beach-combing art robot comes into play.

Very much still a work in progress, [pablo.odysseus]’ beach bot was built to take advantage of the kilometers-wide beaches left by the receding tides near his home. That immense canvas is begging to be groomed, and this bot is built for the task. The running gear itself is simple – an extruded aluminum chassis powered by wheelchair drives with added optical encoders and dragging a retractable rake  – but the bot is bristling with electronics dedicated to navigation.  A pair of Arduinos run the dual odometers, compass, and a GNSS receiver, as well as providing a smartphone interface for on-the-fly changes. The art is composed as a DXF file converted to latitude and longitude points and exported to Google Earth as a KML. That means the bot can just be brought to the beach and allowed to draw autonomously. An early test run is seen below the break; better “brushes” are in the works.

Watching the art unfold on a beach would be relaxing, like watching a zen garden being created. We’re looking forward to [pablo]’s progress on this one. Of course, art bots aren’t the only autonomous machines that big, wide beaches attract.

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Sintering Sand WIth A Laser Cutter

We are all used to Fused Deposition Modeling, or FDM, 3D printers. A nozzle squirts molten material under the control of a computer to make 3D objects. And even if they’re usually rather expensive we’re used to seeing printers that use Stereolithography (SLA), in which a light-catalysed liquid monomer is exposed layer-by layer to allow a 3D object to be drawn out. The real objects of desire though are unlikely to grace the average hackspace. Selective Laser Sintering 3D printers use a laser on a bed of powder to solidify a 3D object layer by layer.

The laser creating a ring.
The laser creating a ring.

While an SLS printer may be a little beyond most budgets, it turns out that it’s not impossible to experiment with the technology. [William Osman] has an 80 W laser cutter, and he’s been experimenting with it sintering beach sand to create 2D objects. His write-up gives a basic introduction to glassmaking and shows the difference between using sand alone, and using sodium carbonate to reduce the melting point. He produces a few brittle barely sintered tests without it, then an array of shapes including a Flying Spaghetti Monster with it.

The results are more decorative than useful at the moment, however it is entirely possible that the technique could be refined. After all, this is beach sand rather than a carefully selected material, and it is quite possible that a finer and more uniform sand could give better results. He says that he’ll be investigating its use for 3D work in the future.

We’ve put his video of the whole process below the break, complete with worrying faults in home-made laser wiring. It’s worth a watch.

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These Sands Of Time Literally Keep Time

Hour glasses have long been a way to indicate time with sand, but the one-hour resolution isn’t the best. [Erich] decided he would be do better and made a clock that actually wrote the time in the sand. We’ve seen this before with writing time on a dry erase board with an arm that first erases the previous time and then uses a dry erase marker to write the next time. [Erich]’s also uses an arm to write the time, using the tip of a sea shell, but he erases the time by vibrating the sandbox, something that took much experimentation to get right.

To do the actual vibrating he used a Seeed Studio vibration motor which has a permanent magnet coreless DC motor. Interestingly he first tried with a rectangular sandbox but that resulted in hills and valleys, so he switched to a round one instead. Different frequencies shifted the sand around in different ways, some moving it to the sides and even out of the sandbox, but trial and error uncovered the right frequency, duration, and granular medium. He experimented with different sands, including litter for small animals, and found that a powder sand with small, round grains works best.

Four white LEDs not only add to the nice ambience but make the writing more visible by creating shadows. The shells also cleverly serve double duty, both for appearance and for hiding things. Shells cause the arms to be practically invisible until they move (well worth viewing the video below), but the power switch and two hooks for lifting the clock out of the box are also covered by shells. And best of all, the tip that writes in the sand is a shell. There’s plenty more to admire about the cleverness and workmanship of this one.

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Putting Sand, Water, and Metal into A 3D Print

[Adam] over at Makefast Workshop writes about some of the tests they’ve been running on their 3D printer. They experimented with pausing a 3D print midway and inserting various materials into the print. In this case, sand, water, and metal BBs.

The first experiment was a mixture of salt and water used to make a can chiller for soda or beer (the blue thing in the upper right). It took some experimentation to get a print that didn’t leak and was strong. For example, if the water was too cold the print could come off the plate or delaminate. If there was too much water it would splash up while the printer was running and cause bad layer adhesion.

They used what they learned to build on their next experiment, which was filling the print with sand to give it more heft. This is actually a common manufacturing process — for instance, hollow-handled cutlery often has clay, sand, or cement for heft. They eventually found that they had to preheat the sand to get the results they wanted and managed to produce a fairly passable maraca.

The final experiment was a variation on the popular ball bearing prints. Rather than printing plastic balls they designed the print to be paused midway and then placed warmed copper BBs in the print. The printer finished its work and then they spun the BB. It worked pretty well! All in all an interesting read.

Propane Tanks Transformed Into Extreme Sandblaster

The [Make It Extreme] team has been racking up the builds lately, and a lot of them are heavy with metalworking. When you’re doing that kind of work, and you put as much care into finishing your builds like they do, it’s a good idea to have access to a sandblaster. So naturally, they built a really nice one.

We’ve featured a couple of [Michalis Mavros] and team’s build recently; you’ll no doubt recall this viciously effective looking spot welder and a sketchy angle grinder cum belt sander. The sandblaster build, centered as it is around scrap propane tanks, has some lethal potential, but luckily the team displaced any remaining gas from the tanks with water before doing any cutting. The design allows for a lot of sand in the tanks, with plans to provide a recycling system for the grit, which is a nice touch. And it works great – they even used it to clean it up before final finishing in the trademark [Make It Extreme] green and black paint job.

What we really like about the video, though, is that it’s a high-speed lesson on metalworking techniques. There’s a ton to learn here about all the little tricks needed to bring a large-scale metalworking project to fruition. It also demonstrates that we really, truly need a plasma cutter and a metalworking lathe.

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