Tattoo your 3D Prints with Velocity Painting

Just when it seems like we’ve juiced all the creative potential out of our 3D printers, a bold new feature lands on the table. Enter Velocity Painting, a concept brought to life by [Mark Wheadon] that textures our 3D prints with greyscale images.

At its core, the technique is straightforward: skin an image onto a 3D print by varying the print speed in specific locations and, thereby, varying just how much plastic oozes out of the nozzle. While the concept seems simple, the result is stunning.

Velocity Painting opens up new ways of expression on top of an existing print with all the skinning opportunities. Imagine adding a texture for realism like this rook that’s been patterned with a brick layout, or imagine an aesthetic embellishment like the flames on [Mark’s] dragon print.

The results speak for themselves, and the growing number of users are proving it. Head on over to the gallery to indulge yourself in this delightful oozing aesthetic that’s sure to turn a few heads.

[Mark Wheadon’s] hack takes the mechanics of how we print and adds another creative tuning knob. If you’re looking for other embellishments for your prints, have a look at [David Shorey’s] work on texturizing fabrics.

Spraychalk Anoints your Sidewalks with Precision Sandprints

Giant lines in the sand are incredibly useful for pleasing the gods and hailing overpassing extraterrestrials. Beautiful, unwarranted spray-painted sidewalks might land you in detention with local law enforcement. Of course, why not have both? With the Sand-and-Spraychalk machine, you can!

The Sand-and-Spraychalk machine Is a moving two-axis CNC machine that can anoint its path with a spray of either sand bits or spray paint.  As with any self-respecting power tool these days, the Spraychalk is driven by a rechargeable Bosch 18 V battery pack. As far as safety goes, leveraging an already-product-proven solution instead of cooking our lawns with questionable LiPos is downright clever.

Elegance is in simplicity, and the Spraychalk is no exception. The entire build is a collection of off-the-shelf parts mixed with a few laser cut plates and a one custom nozzle made of POM (Acetal). Precise spraying might sound like a hard problem, but it’s executed here with just a motor-driven cam and a couple levers. Finally, adapting a 18 V battery pack may seem like a form-factor nightmare, but our creator, [kallibaba], managed to pull it off with just a few laser-cut plates.

The Spraychalk rightfully sits next to its previously mentioned cousins that have graced these pages before. The next time we’re wondering just who vandalized your lawn so majestically, we know where to look!

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Tie-Dyed Filament Sings With Color

Manufacturers dye all sorts of 3D printer filaments on their factory lines; why can’t we? [Richard] takes this idea one step further by creating his own custom multicolored reels of nylon. Printing with these reels produces a vibrant pattern that simply demands our attention and  begs us to ask: how on earth..?

[Richard’s] tie-dye adventure is cleanly documented on the blog.  He simply spools a reel of nylon together and dyes subsections of the spool with a different color. With the filament “paletted” to taste, parts pop of the printer with an eye-catching rib pattern of color.

It’s worth mentioning that nylon is extremely hygroscopic, and dyeing filament in a bath full of colored liquid is sure to get it full of moisture. Then again, nylon’s capacity to absorb water might be why it dyes so well. Nevertheless, filament must be oven-dried (or equivalent) for a successful print. Post-drying, [Richard] doesn’t seem to be having any printing problems, and the results speak for themselves.

3D printers might be frequent fliers on these pages, but we still love seeing small modifications that enhance the visual appeal. What’s more, this trick delivers spectacular results with no modifications to the printer itself. Then again, if this job sounds like just too much work for you, we’d suggest using a sharpie.

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Budget Dehydrator Gives your Damp Filament a Second Chance

If you’ve had the misfortune of leaving your 3D printer filament out on a muggy day or, heaven forbid: showering with it, it’s probably soaked up quite a bit of moisture. Moisture will do more than just make your printer sound like Rice Crispies, it’ll ruin surface finishes and cause the filament to string into thin wisps between separate geometries on the same layer. Luckily for us, though, both [SafetyGlassesRequired] and [Joe Mike Terranella] give us the breakdown on taking a pair of snippers and about $40 in cash to start drying out our filament far away from the possibility of ruining any nearby kitchen ovens.

If you’ve been circling the 3D printer community for a while, you might have already heard about this trick. But with the arrival of a curiously-culinary-looking contraption called PrintDry, we can’t let the elephant in the room keep silent for much longer. Rather than risk our own pennies and leave ourselves stranded with a device that only makes the jerky on the box cover, [SafetlyGlassesRequired] and [Joe Mike Terranella] kindly prove our suspicions for us once and for all: a food dehydrator works perfectly for drying all that filament that we left out in the rain!

Clumsiness aside, a dehydrator isn’t a bad investment in the long run. Not only can we keep our supply dry, we might just be able to give all that freebie filament (that we dug out of the trash) a second life by resetting it to a clean, dry state.

These dehyrdators will toast all that moisture out of your filament, but it wont keep them dry whilst printing. For that problem, you’ll need to summon a heated drybox like this one.

[Joe Mike’s] solution will run us about $40. If you can do better, let us know in the comments.

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Prestretched Fabric Prints Pop into the Third Dimension

Printing on fabric might be a familiar trick, but adding stretch into the equation gives our fabric prints the ability to reconstitute themselves back into 3D. That’s exactly what [Gabe] has accomplished; he’s developed a script that takes open 3d meshes and converts them to a hexagonal pattern that, when 3D-printed on a stretched fabric, lets them pop into 3D upon relaxing the fabric.

[Gabe’s] algorithm first runs an open 3D surface through the “Boundary-First Flattening Algorithm,” which gives [Gabe] a 2D mesh of triangles. Triangles are then mapped to hexagons based on size, which produces a landscape of 2D hexagons. Simply printing this hexagonal pattern onto prestretched fabric defines the shape of the object that will surface when the fabric is allowed to relax. As for how to wrap our heads around the mapping algorithm, as [Gabe] explains it, “The areas that experienced the most shrinkage in the flattening process should experience the least shrinkage when the fabric contracts after printing, and the regions that experienced little to no shrinkage in the flattening process should contract as much as possible in the fabric representation.”

If that seems tricky to visualize, just imagine taking a cheap halloween mask and trying to crush it flat onto a table. To smush it perfectly flat, some sections need to stretch while others need to shrink. Once flat though, we can simply keep stretching to remove all the sections that needed to shrink. At this point, if our material were extremely elastic, we could simply let go and watch our rubber mask jump back into 3D. That’s the secret behind [Gabe’s] hexagonal pattern. The size and spacing of these hexagons limit the degree to which local regions of the fabric are allowed to contract. In our rubber mask example, the sections that we stretched out the furthest have the most to travel, so they should contract as much as possible, while the sections that shrank in the initial flattening (although we kept stretching until they too needed to stretch) should shrink the least.

We’ve seen some classy fabric-printing tricks in the past. If you’re hungry for more 3D printing on fabric, have a look at [David Shorey’s] flexible fabric designs.

Thanks for the tip, [Amy]!

Digikey Tips Its Hat To Kicad With Its Own Library

Digikey might wow us with their expansive stock, but now they’re wowing us with a personal gesture. The US-based electronics vendor is nodding its head in approval to KiCad users with its very own parts library. What’s more, [Chris Gammell] walks us through the main features and thought process behind its inception.

With all the work that’s going into this library, it’s nice to see features showing that Digikey took a thorough look at KiCad and how it fits into the current state of open-source PCBA design. First off, this library follows a slightly different design pattern from most other KiCad libraries in that it’s an atomic parts library. What that means is that every symbol is linked to a specific manufacturer part number and, hence, gets linked to a specific footprint. While this style mirrors EagleCad’s; KiCad libraries usually separate symbols from footprints so that symbols can be reused and parts can be more easily swapped in BOMs. There’s no “best” practice here, so the folks at Digikey thought they’d expose the second option.

Next off, the library is already almost 1000 parts strong and set to grow. These aren’t just the complete line of Yageo’s resistor inventory though. They actually started cultivating their library from the parts in Seeed Studio’s open parts library. These are components that hobbyists might actually use since some assembly services have a workflow that moves faster with designs that use these parts. Lastly, since all parts have specific vendor part numbers, BOM upload to an online cart is more convenient, making it slightly easier for Digikey to cha-ching us for parts.

Yes, naysayers might still cry “profit” or “capitalism” at the root of this new library, but from the effort that’s gone into this project, it’s a warm gesture from Digikey that hits plenty of positive personal notes for hobbyists. Finally, we can still benefit from plenty of the work that’s gone into this project — even if we don’t use it as intended. The permissive license lets us snag the symbols and reuse them however we like. (In fact, for the sharp-eyed legal specialists, they actually explicitly nullified the clause stating that derivative projects need not be licensed with a creative-commons license.)

With maturing community support from big vendors like Digikey, we’re even hungrier to get our hands on KiCad V.

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Papercraft-Inspired Snake-bot Slithers like a Real One

Blend the Japanese folding technique of Kirigami with an elastomer actuator, and what have you got? A locomoting snake robot that can huff around its own girth with no strings attached! That’s exactly what researchers at the Wyss Institute and Harvard School of Applied Sciences did to build their Kirigami Crawler.

Expanding and contracting propel this crawler forward. As the actuator expands, the hatched pattern on the plastic skin flares out; and when it contracts, the skin retracts to a smoother form. The flared hatch pattern acts like a cluster of little hooks, snagging multiple contact points into the ground. When the skin retracts, these hooks fold back inside while giving the body a slight push forward in the process. It’s a clever tactic, and almost identical to the way real-world snakes propel themselves. In fact, after iterating on a few skin patterns, they found that a trapezoidal pattern, which most closely resembles that of snakeskin, can cover ground fastest.

We’re thrilled to see such authentic biomimicry come to us without any extreme tooling or special molds. Still not satisfied with your share of crawling robots for one day? Have a peek into the past, and indulge yourself with a sine-wave locomotion.

Thanks for the tip, [Olivia]!

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