Thermal printer with a loop of thermochromic foil inserted in it, printing digits of Pi on the loop.The digits gradually disappear from the foil as it exits the printer.

Celebrating The Infinity Of Pi Day With Thermochromic Foil

March 21, 2022 by Arya Voronova 8 Comments

It might take you some time to understand what’s happening in the video that Hackaday alum [Moritz Sivers] shared with us. This is [Moritz]’s contribution for this year’s Pi Day – a machine that shows digits of Pi in a (technically, not quite) infinite loop, and shows us a neat trick we wouldn’t have thought of.

The two main elements of this machine are a looped piece of thermochromic foil and a thermal printer. As digits are marked on the foil by the printer’s heating element, they’re visible for a few seconds until the foil disappears from the view, only to be eventually looped back and thermally embossed anew. The “Pi digits calculation” part is offloaded to Google’s pi.delivery service, a π-as-a-Service endpoint that will stream up to 50 trillion first digits of Pi in case you ever need them – an ESP8266 dutifully fetches the digits and sends them off to the thermal printer.

This machine could print the digits until something breaks or the trillions of digits available run out, and is an appropriate tribute to the infinite nature of Pi, a number we all have no choice but to fundamentally respect. A few days ago, we’ve shown a similar Pi Day tribute, albeit a more self-sufficient one – an Arduino calculating and printing digits of Pi on a character display! We could’ve been celebrating this day for millennia, if Archimedes could just count a little better.

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A Fractal Papercraft Tree

March 20, 2022 by Jenny List 15 Comments

Sometimes there are projects that we introduce with a bit of context, some background, and other times as with [RayP2]’s fractal papercraft tree, we introduce them simply because they are beautiful.

It’s a deceptively simple design of a repeating pattern of the same shape getting ever smaller with each iteration, and terminating in a tetrahedron with branches from each of its faces. It’s not origami, instead it’s a cut-and-glue design, and its construction is a surprisingly involved affair with some lateral thinking required to bend the tabs on the smaller branches. The design was first prototyped with plain paper, before a final version was made with card stock. The part that makes it exceptional is that he used shiny gold card stock with the gold side on the inside, meaning that when lit from the trunk the end of each branch glows attractively. Fitting the light required a modification to the trunk design, but this doesn’t take away from the whole.

The result is an attractive sculpture, a talking point, and something with a mathematical angle to boot, which we like. It’s certainly not been the first papercraft ptoject we’ve shown you, though perhaps these paper retrocomputers are a little less artistic.

3D Printed Molds For Casting Rose’s Metal

March 17, 2022 by Kristina Panos 22 Comments

Have you ever played with Rose’s metal? It’s a fusible alloy of bismuth, lead, and tin with a low melting point of around 100 °C. Historically, it’s been used as a solder for cast iron railings and things, and as a malleable pipe filler material to prevent crimping while a pipe is bent.

[Ben Healey] has been playing around with Rose’s metal and some PETG printed molds, making everything from Star Wars Imperial credits to chess pieces to leather stamping tools. In the video after the break, [Ben] takes us through the process, beginning with mold-making from STLs — something he picked up from another YouTuber.

He recommends adding registration marks to multi-part molds in order to keep everything lined up, and adding a small recess in the seam for easy separation with a flat-head screwdriver. So far, the molds have held up to multiple pours, though [Ben] did print them rather thick and is glad he did.

As far as making liquid metal, [Ben] used a cast iron pot with a convenient pour spout, and a blowtorch. He added graphite powder to the molds in an effort to make them give up the goods more easily. To finish the pieces, [Ben] cut the flashing with tin snips and used sandpaper and a Dremel to smooth the edges. Copper plating didn’t work out, but [Ben] is going to try it again because he thinks he screwed something up in the process. He’s also going to try printing with TPU, which we were just about to recommend for its flexibility.

There are many ways to cast metal on the (relatively) cheap. Have you considered Kinetic Sand?

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How To Make Laser-cut Decals On The Cheap

March 12, 2022 by Donald Papp 13 Comments

Want to make a sweet adhesive decal with a complex design and floating elements, but all you have is a laser cutter and some tape? Good news, because that’s all you need with this method of creating adhesive tape decals on a laser cutter demonstrated by the folks at [Lasers Over Los Angeles]. The overall technique is very similar to creating vinyl decals and using tape transfer to apply them, but is geared towards laser cutters and nice, cheap tape.

This method also makes applying to non-flat surfaces a breeze.

The way it works is this: paper-based tape (such as blue painter’s tape) is laid down in strips on the laser cutter’s honeycomb bed, forming a nice big rectangle big enough for the intended design. Then, the laser cutter cuts vector art into the tape, resulting in an adhesive decal ready to be stuck to some other surface. Transferring is done by using good quality clear packing tape to “pick up” the decal, then move it to where it needs to be.

To do this, one lays strips of packing tape onto the top of the design on the laser bed, then lifts the design up and away. Move the design to its destination (the clear packing tape helps in eyeballing the final position), press the decal onto the final surface, and carefully peel away the clear packing tape. This works because the packing tape sticks only weakly to the back of the painter’s tape; it’s a strong enough bond to hold the decal, but weak enough that the decal will stick to a surface even better.

It’s true that painter’s tape isn’t as durable as vinyl and the color selection is a bit limited, but design-wise one can go as big as the laser bed allows, and the price is certainly right. Plus it’s easily cut by even the most anemic of diode lasers.

Speaking of desktop vinyl cutters, they may have small working areas compared to most laser cutters, but they have some fantastic workshop applications. They can even do home PCB fabrication, by way of knocking out three essential pieces: the etching mask, solder mask, and solder stencil.

Nail This Tricky Kumiko Pattern

March 11, 2022 by Matthew Carlson 4 Comments

[Pask Makes] has previously made Kumiko patterns in wood and was happy with the results, but he wondered if he could make something visually similar from metal instead of wood.

For that, he reached for nails as it is a cheap source of uniform small rods of metal. Kumiko is, funny enough, a technique known for joining small pieces of wood without nails. There are many different patterns that use the technique and most are inspired by nature. It is the pressure of the wood in the pattern itself that holds it together and requires dedicated planning and thousands of minute adjustments. Since [Pask] was using a MIG welder to hold the nails together, it isn’t technically Kumiko but rather a Kumiko pattern.

The first step was to take the coating off the nails, which is something a little acid does a wonderful job with. After dropping a little acid, his nails were prepped and he was ready to tack them together. He printed a template on a sheet of paper and used a straight edge and a palm router with a groove bit to cut little channels for each of the nails to sit in. The nails were trimmed to the correct width with the help of a small jig. After he had tacked the nails together, he came back and filled in the centers.

It’s a straightforward little project that creates a beautiful pattern and it’s a good reminder that simple materials can make complex things. If you prefer the wood look, this Kumiko guitar might be more to your taste. Video after the break.

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Pop Goes The Mechanical Ping Pong Sculpture

March 7, 2022 by Matthew Carlson 12 Comments

In the waiting rooms of some dentists or doctors, you might have seen a giant metal ball rolling around in a large glass case. While it sure beats looking through those magazines, the sculpture can’t have come cheap. But not all of us want to pay high-end prices for fun toys. As a more cost-effective alternative, [JBV Creative] built an awesome 3D-printed ping pong sculpture.

The basic concept is the same as those fancy sculptures: a ball goes up, moves through some sort of impressive range of motion as it makes its way back down, and some sort of drive mechanism pushes it back to repeat the cycle anew. The design of this particular art piece is no different. A ping-pong ball falls down a funnel into a queue where balls are slowly loaded via a 12-way Geneva mechanism. An Archimedes spiral cam charges an elastic band that yeets the ball up and out of the track and sends it sailing through the air and down inside the funnel mentioned earlier. Everything on this sculpture is 3D-printed aside from the rubber bands and the ping pong balls.

What’s tricky about these sorts of things is the precision required both in printing and in design. It needs to run for hundreds if not thousands of hours and make no mistake. Making something work correctly 99% of the time is hard, but that last 1% can be almost as much work as that first 99%. [JBV Creative]’s first attempt had a catapult mechanism and he printed and tried out several scoops, but none gave the trajectory that he was looking for.

[JBV Creative] tried a plunger mechanism, but without a counterbalance weight providing the power, it just didn’t have enough oomph to launch the ball. Luckily, holes were included in the design, so it was relatively easy to adapt what had already been printed to use rubber bands instead. An additional goal was to have no visible fasteners, so everything needed to be mounted from the back. Check it out in action after the break.

It’s an incredible project that took serious thought, dedication, and in [JBV Creative]’s words, plenty of CAD twirling. It’s a great lesson in iterating and experimentation. If your talents are more soldering-based rather than CAD-based, perhaps a circuit sculpture is more up your alley?

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3D Printed Suncatcher Shines In The Light

February 25, 2022 by Lewin Day 9 Comments

Diffraction gratings create beautiful rainbow patterns when interacting with natural white light, and [audreyobscura] was familiar with their properties. Thus, she set about producing an attractive 3D-printed suncatcher ornament that positively shines in the sun.

The design is straightforward, consisting of a 3D printed frame made of pieces glued together using QuickGrab glue. The pieces come together into a 7-segment star design, with a subtle 3D structure to it which helps add strength in addition to looking good.

Once assembled, sections of plastic diffraction grating are cut to size using a Curio desktop cutter. These are then glued into each segment of the star. While it’s possible to 3D print pieces with diffraction-grating like effects, using the film in this way allows light to pass through the suncatcher to create a more impressive effect.

On a cloudy day, the suncatcher looks almost entirely unassuming. However, when Earth’s nearest star shines, it projects glorious rainbows throughout the room, and letting it sway in the breeze lets the light play across the walls.

It’s a nice build, and a relatively easy ornament to make even if you’re new to 3D printing. We do like a good bit of decoration around here, especially if it’s a tiny version of a real TV. Video after the break.

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