Cutting Balsa Wood With Air (Oh, And A Laser)

[DIY3DTech] likes using his Ortur laser cutter for balsa wood and decided to add an air assist system to it. Some people told him it wasn’t worth the trouble, so in the video below, he compares the results of cutting both with and without the air assist.

The air assist helped clear the cut parts and reduced charring in the wood. The air system clears residue and fumes that can reduce the effectiveness of the laser. It can also reduce the risk of the workpiece catching on fire.

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Recreating Classic Model Kits With Modern Tech

It used to be that if you wanted to make a nice scale model of an airplane, you’d be building the frame out of thin balsa ribs and covering it all up with tissue paper. Which incidentally was more or less how they built most real airplanes prior to the 1930s, so it wasn’t completely unreasonable to do the same on a smaller scale. But once injection molded plastics caught on, wood and tissue model kits largely went the way of the dodo.

[Marius Taciuc] wanted to share that classic model building experience with his son, but rather than trying to hunt down balsa kits in 2019, he decided to recreate the concept with modern techniques. His model of the Supermarine Spitfire, the vanguard of the British RAF during the Second World War, recreates the look of those early model kits but substitutes 3D printed or laser cut components for the fragile balsa strips of yore. The materials might be high-tech, but as evidenced by the video after the break, building the thing is still just as time consuming as ever.

Using a laser cutter to produce the parts would be the fastest method to get your own kit put together (you could even cut the parts out of balsa in that case), but you’ll still need a 3D printer for some components such as the propeller and cowling. On the other hand, if you 3D print all the parts like [Marius] did, you can use a soldering iron to quickly and securely “weld” everything together. For anyone who might be wondering, despite the size of the final plane, all of the individual components have been sized so everything is printable on a fairly standard 200 x 200 mm print bed.

While there’s no question the finished product looks beautiful, some might be wondering if it’s really worth the considerable effort and time necessary to produce and assemble the dizzying number of components required. To that end, [Marius] says it’s more of a learning experience than anything. Sure he could have bought a simplified plastic Spitfire model and assembled it with his son in an afternoon, but would they have really learned anything about its real-world counterpart? By assembling the plane piece by piece, it gives them a chance to really examine the nuances of this legendary aircraft.

We don’t often see much from the modeling world here on Hackaday, but not for lack of interest. We’ve always been in awe of the lengths modelers will go to get that perfect scale look, from the incredible technology packed into tiny fighter planes to large scale reproductions of iconic engines. If you’ve got some awesome model making tips that you think the Hackaday readership might be interested in, don’t be shy.

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Hacking Balsa To Make It Stronger

Balsa wood has long been revered for its strength and lightweight composition, two properties that make it ideal for building model structures and airplanes. Researchers from the US and China have managed to make balsa even stronger and more useful. They’ve found a way to change its structure, turning it into a carbon sponge that’s strong enough to withstand repeated mechanical strain, but light enough to sit atop a dandelion gone to seed.

Using common chemicals like lye and hydrogen peroxide, the scientists burned the hemicellulose and lignin fibers that make up balsa’s rectangular cell walls. Then they incinerated the sample at 1,000°C, which morphed the cellular structure into a cross between a helical spring and a honeycomb.

Normally, carbonized wood just collapses under weight. But by first burning the cell fibers, the carbonization process results in a balsa carbon sponge capable of withstanding thousands of compressions before deforming. The researchers used the new material as part of a mechanical strain sensor prototype for wearable electronics, and they see a solid future for the material in water purification devices, supercapacitors, and rechargeable batteries.

This is big news for a society that’s trying to find more environmentally responsible ways to keep going full steam ahead in technological growth. Balsa trees grow fast, averaging 10+ feet per year, so this is a more sustainable alternative to graphene and carbon nanotubes. We’re excited to see what comes of this hack of nature. You can read the full paper here.

Even in its natural state, balsa is an interesting material. We once saw someone exploit its water retention abilities to make a rain-activated, shape-shifting prototype for roofing shingles.

Thanks for the tip, [Gervais].

Shapeshifting Material For Weather Adaptive Structures

Where [Isaac Newton] had his apple (maybe), [Chao Chen] found inspiration in a pine cone for a design project that lead to a water-sensitive building material. He noticed the way some pine cones are sensitive to water, closing up tight when it rains, but opening up with dry conditions. Some dissection of a pine cone revealed [Mother Nature’s] solution – different layers that swell preferentially when exposed to moisture, similar to how a bimetallic strip flexes when heated. [Chao Chen’s] solution appears to use balsa wood and a polystyrene sheet laminated to a fabric backing to achieve the same movement – the wood swells when wet and pulls the laminate flat, but curls up when dry.

As [Chao] points out, the material is only a prototype, but it looks like a winner down the road. The possibilities for an adaptive material like this are endless. [Chao] imagines a picnic pavilion with a roof that snaps shut when it rains, and has built a working model. What about window shutters that let air and light in but close up automatically in that sudden summer storm? Self-deploying armor for your next epic Super Soaker battle? Maybe there are more serious applications that would help solve some of the big problems with water management that the world faces.

Make sure you check out the video after the break, with a more decorative application that starts out looking like an [M.C. Escher] print but ends up completely different.

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ArduSpider Entertains Children And Exercises Pets

There are so many good things about [Jose Julio’s] robotic spider. It’s design is dainty yet robust, and the behaviors encoded in the firmware are nothing short of spectacular.

The body is built from a piece of balsa wood in between sheets of carbon fiber. The legs are carbon rods, using two servo motors for left and right leg movement, and a third servo which can move the intermediary legs like the roll axis of a plane. An IR sensor rides on the front for obstacle avoidance, with system control courtesy of an Arduino. For more hardware info check out his build log.

Don’t miss the video after the break. You’ll see that the little bot can be manually controlled, or allowed to roam free. As we said before, the behavior is fantastic. Not only has [Jose] programmed interesting characteristics like the spider getting tired and sitting down for a while, but when it is awakened it leaps into the air. The movements are fun to watch for human and feline alike; if only your house cat could be so lucky.

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