Reuleaux Coaster

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.

This robot arm engraved 400 coasters in a day but maybe you would prefer if you simply had your beer delivered to your new coasters.

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This Method of Gluing onto Curves Sucks!

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.

Improved Game Tokens with Laser Cutting and Clever Design

[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!


Two-Piece Boxes Thanks to Laser-Cut Flex Hinges

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.

Need slots and tabs for boxes but you’re more familiar with FreeCAD? These parametric scripts will get you started, and we’ll bet you can port the flex-hinge bit easily, too.

Well, That Was Quick: Heng Lamp Duplicated

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.

[msraynsford]’s version replaces the floating spheres with floating cylinders, which are easier to fabricate in layers on a laser cutter, but otherwise the copy is fairly true to the aesthetics of the original. Pretty sweet!
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Converting Kids’ Hand-Drawings to G-Code

[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.

Screenshot of Martin's scanning and G-code maker program
Martin’s scanning and G-code maker program

[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.

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DIY Vacuum Table Makes Lasering Even Easier

If you’ve ever tried to laser flexible rolls of material you’ll know it can be really annoying to setup in the laser cutter.

Most of the time we use magnets, but then you have to make sure the magnets are clear of the work path — and then you end up wasting extra material… It’d be amazing to have a vacuum table that just sucks down your work piece to keep it in place! As it turns out, it’s not that hard to make!

After getting frustrated lasering warped material themselves, [Martin Raynsford] and the gang decided to make their very own vacuum table — using a laser cutter of course. Continue reading “DIY Vacuum Table Makes Lasering Even Easier”