Prolific creator [Martin Raynsford] recently created a plus-sized edible version of his laser-cut Marble Machine for a Cake International exhibit and competition; it seemed simple to do at first but had quite a few gotchas waiting, and required some clever problem-solving.
The original idea was to assemble laser-cut gingerbread parts to make the machine. Gingerbread can be laser-cut quite well, and at first all seemed to be going perfectly well for [Martin]. However, after a few days the gingerbread was sagging badly. Fiddling with the recipe and the baking was to no avail, and it was clear [Martin] needed to find something other than gingerbread to work with. After experimenting, he settled on a modified sugar paste which kept its shape and dried hard enough to work with. (While appearing to stretch most people’s definition of “cake” past the breaking point, the category [Martin] entered in the competition allows it.) The parts were cut by hand using laser-cut wood parts as a guide, then finished in a food dehydrator overnight.
The next problem was how to create the large spiral which forms the main ramp. The answer was to laser-cut a custom support structure that supported the piece while it dried out, and doubled as a way to transport the piece safely. High stress points got extra layers cemented with sugar glue, and some parts were reinforced internally with strands of uncooked spaghetti. Everything was sealed with an edible shine, which [Martin] says acts as a kind of varnish for cakes. A video demonstration is embedded below. Continue reading “Problems that Plagued an Edible Marble Machine”→
What’s better than a cool build? A cool build with valuable advice! Add a few flashy pictures and you have [Martin Raynsford]’s Reuleaux triangle coasters blog post. [Martin Raynsford] wanted to share his advice about the importance of using jigs and we’re sold. He was able to make 100 coasters in a single day and if he’s like us, after number ten, the work gets a little hurried and that is when mistakes are made.
Jig is a broad term when it comes to tooling but essentially, it holds your part in place while you work on it. In this case, a jig was made to hold the coaster pieces while they were glued together. [Martin Raynsford] didn’t need any registration marks on the wood so even the back is clean. If you look closely, the coaster is two parts, the frame and the triangle. Each part is three layers and they cannot separated once the glue dries. If any part doesn’t line up properly, the whole coaster is scrap wood.
Sometimes the right tool for a job can be unusual, and this sucked only in the sense that vacuum sealing was involved. Recently [Martin Raynsford] found himself in a situation of needing to glue a wood veneer onto a curved surface, but faced a shortage of clamps. His clever solution was to vacuum-seal the whole thing and let the contour-hugging plastic bag take care of putting even pressure across the entire glued surface. After the glue had set enough to grip the materials securely, the bag was removed to let the whole thing dry completely. Gluing onto a curved surface has never been so clamp-free.
The curved piece in question was made from dozens of layers of laser-cut plywood, stacked and glued to make the curved lid of a custom-built chest. It might have been just the right shape, but it wasn’t much to look at. As you can see, giving it a wood veneer improved the appearance considerably. Wood veneers are attractive and versatile; we’ve seen for example that LEDs will shine through wood veneer quite easily.
[Martin Raynsford] is a prolific project maker, especially when it comes to using a laser cutter. These laser-cut token counters for the board game Tigris & Euphrates demonstrate some clever design, and show that some simple touches can make a big difference.
In the digital version of the game, the tokens conveniently display a number representing their total power value. [Martin] liked this feature, and set out to design a replacement token for the tabletop version that could display a number while still keeping the aesthetic of the originals. The tokens were designed as a dial with a small cutout window to show a number, but the surface of the token showing color and icon is still mostly unchanged.
Magnets hold the top and bottom together, and because of the small size of the assembly, no detents are needed. Friction is enough to keep things from moving unintentionally. The second noteworthy design feature is the material for the top layer of the token. This layer is made from 0.8 mm birch plywood; a nice and thin top layer means a wider viewing angle because the number is nearer to the surface. If the top layer were thicker, the number would be recessed and harder to see.
[Martin] made the design file available should anyone wish to try it out. No stranger to games, he even once game-ified the laser itself, turning it into a physical version of Space Invaders. Be sure to check it out!
It sounds like a challenge from a [Martin Gardner] math puzzle from the Scientific American of days gone by: is it possible to build a three-dimensional wooden box with only two surfaces? It turns out it is, if you bend the rules and bend the wood to make living hinge boxes with a laser cutter.
[Martin Raynsford] clearly wasn’t setting out to probe the limits of topology with these boxes, but they’re a pretty neat trick nonetheless. The key to these boxes is the narrow to non-existent kerf left by a laser cutter that makes interference fits with wood a reality. [Martin]’s design leverages the slot and tab connection we’re used to seeing in laser-cut boxes, but adds a living flex-hinge to curve each piece of plywood into a U-shape. The two pieces are then nested together like those old aluminum hobby enclosures from Radio Shack. His GitHub has OpenSCAD scripts to parametrically create two different styles of two-piece boxes so you can scale it up or (somewhat) down according to your needs. There’s also a more traditional three-piece box, and any of them might be a great choice for a control panel or small Arduino enclosure. And as a bonus, the flex-hinge provides ventilation.
That didn’t take long at all! We covered a pretty cool lamp with a novel magnetic switch mechanism, and [msraynsford] has his version laser cut, veneered, a video posted on YouTube (embedded below), and an Instructable written up before we’d even caught our breath.
For those who missed it, the original Heng lamp is a beautiful design with a unique take on a magnetic switch. As with the original, the secret sauce is a switch inside that’s physically held closed by the two magnets. It’s a pretty clever mechanism that looks magical to boot.
[Martin Raynsford] wrote a program that converts a black-and-white 2D image to G-code so that his laser printer could then etch the image. Not satisfied with just that, he used his laser printer to make a scanner that consists of a stand for his webcam and a tray below it for positioning the paper just right. The result was something he took to a recent Maker Faire where many kids drew pictures on paper which his system then scanned and laser etched.
[Martin’s] program, written in C#, does the work of taking the image from the webcam using OpenGL and scanning it line by line looking for pixels that surpass a contrast threshold. For each suitable pixel the program then produces G-code that moves the laser to the corresponding coordinate and burns a hole. Looking at the source code (downloadable from his webpage) it’s clear from commented-out code that he did plenty of experimenting, including varying the laser burn time based on the pixel’s brightness.
While it’s a lot of fun writing this code as [Martin] did, after the break we talk about some off-the-shelf ways of accomplishing the same thing.