From Hoverboard To Scooter

February 28, 2022 by Matthew Carlson 4 Comments

I’m sure anyone who had seen Back To The Future was more than a little disappointed when “hoverboards” started appearing on the scene. They didn’t float and they looked fairly ridiculous for anyone over 12. But they have the huge advantage of being cheap and easy to find. [Made By Madman] breaks down a hoverboard for parts to make an incredible custom electric scooter.

The first step after breaking things down for parts was to break the wheel hub motors. He pulled out the axle and started machining a new one using the lathe and a milling machine. A quick temper later, he had a sturdy steel axle. An adapter for a disc brake was milled that could attach to the wheel. The TIG welder came out to weld up a box out of some aluminum to hold the electronics. The wheel had a bracket welded on with a spring shock absorber to help smooth the ride. The fork was machined on the lathe and belt sander, but actual shocks came from an old bicycle. To attach the fork to the frame, [Madman] bends a piece of bar stock into shape; like a madman. The handlebars were taken from the bicycle and the fork was extended up to an adult height.

A quick test ride in the alley showed that the back shock wasn’t strong enough, so he swapped it with a strong one. All the parts got a powder coat. Electronics wise, it has a standard speed controller and a custom battery made from 18650 cells wired up in a 13s6p configuration and bundled together into a package. After a significant amount of wiring, he took it for a test drove and we love seeing him zip around the streets in the snow.

So many parts here are machined to press-fit tolerances and then welded on. The skill, videography, and effort that went into this were just incredible. If you’re feeling inspired and don’t have a lathe on hand, perhaps this 3d printed scooter might be a bit more your speed. Video after the break.

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Swap The Laser For A Vortex Cannon And You Have… Lift?

February 28, 2022 by Matthew Carlson 6 Comments

When people are thinking of the future of space travel, an idea that floats around is a spaceship with a giant solar sail pushed along by a massive laser. Inspired by the concept but lacking a giant laser, [Tom Stanton] build a small craft powered by a vortex cannon.

Creating a vortex is hard enough, but creating a vortex with enough oomph to travel a longer distance and push something takes some doing. [Tom] started with some cheap solenoids, but had a few issues. Their interior nozzles were quite small, which restricted airflow. He used four valves all plumbed together to provide the volume of air needed. Additionally, he found that their response time was lacking. They couldn’t quite switch off quickly enough so instead of a puff of air, it pushed out something closer to a stream. To compensate, [Tom] 3d printed and tried a few different sizes of cone nozzles to see if that helped. Unfortunately, it did not. So he combined the nozzle with an expansion chamber that allowed the pressure wave to shorten, then it narrows to speed it up again. This provided a decent vortex.

Next [Tom] turned to his craft. After designing a 3d model, he had a template to cut out some shapes from paper and taped them together to form a light vehicle that can capture the vortex. The initial tests weren’t too promising as the craft twisted and the string that it traveled on had too much friction. Switching to a vertical test showed more promise but trying to generate multiple vortexes rapidly was unsuccessful as the turbulence from the previous rings broke up the newer rings.

So what’s to be learned from this? It seems like he doesn’t have much to show. [Tom] tweaked and iterated his way to a working vortex cannon and has continued to refine his craft. Hopefully, in the future, we’ll see a fully-functional version of this. The lesson is to keep enumerating the possibilities. Like this webcam based posture sensor iterating its way to success. Video after the break.

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Drift Trike Puts A New Spin On Things With Ice Wheels

February 25, 2022 by Matthew Carlson 6 Comments

A drift trike is a small sturdy tricycle with a powered front wheel and rear wheels with low friction so that you can drift. They’re fun but there are tons of them. Nowadays, if you want to make your own drift trike that stands out, you have to put your own spin on it. And in terms of extra spin, what better way to do it,than to use ice for the wheels. [Sam Barker] started by breaking down an old used BMX bike. A front-wheel hub motor wasn’t available so he had to make some modifications to use his rear-wheel one as a front wheel. After tweaking the seat to put more weight on the front wheel for better traction, it was time to get started on wheels.

Rather than using straight ice, he settled on using a composite. Inspired by Pykrete, he swapped the wood pulp for cotton fibers. After weighing out different percentages of fiber to water, he had a half dozen or so different samples to test. What he found was that anything about 2% was quite strong to the point where smacking it with a hammer didn’t do much. Happy with the results, he 3D printed a mold to hold the ice as it hardens. [Sam] pulled it out a little too early only to have the some of the unfrozen middle leak out. He refilled the mold and got a second wheel going. After waiting for it to fully freeze, he had one and a half wheels and it was time to go for a spin. We appreciate the furze-esk music during the drifting as he is a clear inspiration throughout all of this. We love seeing the tire skids on the pavement, knowing they’ll evaporate soon.

It’s telling that wheels lasted longer than the frame. He admits he just got his MIG welder, so perhaps next time with more practice his tacks will be a little stronger. [Sam] has a love for making electronic vehicles as he’s made a monowheel, a bicycle, and now a tricycle. Perhaps some sort of giant four-wheeled inline skate is next? Other drift trikes don’t go the route of reducing friction but instead focus on delivering so much torque to the wheels that they can’t help but slip. Video after the break.

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Better Kerf Cuts With A CNC Bit

February 25, 2022 by Matthew Carlson 8 Comments

Bending wood is a complex affair. Despite the curves inherent in trees, most wood does not naturally want to bend. There are a few tricks you can use to bend it however, such kerf cutting and steaming. [JAR made] has a clever hack to make better kerf cuts using a CNC bit.

Typically kerfs are cut with a table saw or a miter saw set to trench. Many laser-cut box generations use kerfs to allow the piece to bend. The downside is that the cuts are straight cuts that are the same thickness throughout. This means that when the wood is bent into its shape, there are large gaps that need to be filled if you want the wood to look continuous. The hack comes in by using a router (not the networking kind) with a 6.2-degree taper. This means that the kerfs that it makes are angled. By placing the right amount of cuts and spacing them out equally, you get a perfectly rounded curve. To help with that even spacing, he whipped up a quick jig to make the cuts repeatable. Once all the cuts were made, the time to bend came, and [JAR made] used some hot water with fabric softener to assist with the bend. His shelves turned out wonderfully.

He makes the important statement that this CNC bit isn’t designed with this use case in mine and the chances of it snapping or breaking are high. Taking precautions to be safe is key if you try to reproduce this technique. Perhaps you can bust out some framing lumber and bend it into some beautiful furniture.

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Finding Lo-fi In All The Strange Places

February 23, 2022 by Matthew Carlson 12 Comments

If you haven’t heard any lo-fi music yet, it stands for low-fidelity music. Lofi music today is characterized by audio imperfections such as cable noise or tape hiss. To get a pleasantly warm imperfect sound, many artists turn to vintage equipment. [HAINBACH] found an excellent instrument, the obsolete classroom tool known as magnetic card audio recorders.

The basic mechanism of the device is that it reads and writes to the two tracks on the quarter-inch tape fed through it. One track is meant for the teacher and one track is meant for the student. Originally designed to assist language learners, we can see why it would be an ideal source of good lo-fi samples. The microphone and speaker need to be high quality to hear the nuances of the example sentence. [HAINBACH] also admires the general tone and timbre of the device as opposed to just using a cassette recorder.

The tape in question is glued to little plastic cards. With some modification, you can run the card backward, create a loop, or stitch sections together. With multiple machines, you can run the card from one machine directly into another. They were made by several companies and can be found relatively cheap on online auction houses. While we can’t credit [HAINBACH] for coming up with the idea as it was featured in the movie Baby Driver, it’s still an example of an awesome hack.

Magnetic tape has long been a fascination of musical instruments. This Crudman, which is a modern-day interpretation of the much older Mellotron from 1963, is a great example of that.

Video after the break.

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Bend It Like (Sonar) Beacon With A Phased Array

February 23, 2022 by Matthew Carlson 7 Comments

Ultrasonic transducers are incredible, with them you can detect distances, as well as levitate and peer through objects. They can emit and receive ultrasonic soundwaves (typically above 18khz) and just like all waves, they can be steered via a phased array. [Bitluni] was trying to accurately measure distances but found the large field of view of the sensor was just too imprecise, so he made a phased array of transducers.

The inspiration came from a Hackaday Supercon talk from 2019 about phased arrays. [Bitluni] walks through an excellent explanation of how the array works with a bucket of water and his finger, as well as a separate simulation. By changing the phase offset of the different array members, the beam can effectively be steered as interference muffs the undesired waves. Using a set of solenoids, he created a test bench to validate his idea in a medium he could see; water. The solenoids fire a single pulse into the water creating a wave. You can see the wave move in the correct direction in the water, which validates the concept. A simple PCB sent off to a fab house with a stencil offers a surface to solder the transducers and drivers onto. An ESP32 drives the 8 PWM signals that go to the transmitters and reads in the single receiver via a small amplifier. Still not content to let the idea be unproven, he sets up the receiver on his CNC gantry and plots the signal strength at different points, yielding beautiful “heat maps.”

It sweeps a 60-degree field in front of it at around 1-3 frames per second. As you might imagine, turning sound wave reflections into distance fields is a somewhat noisy affair. He projects the sonar display on top of what we can see in the camera and it is fun to see the blobs line up in the correct spot.

We noticed he built quite a few boards, perhaps in the future, he will scale it up like this 100 transducer array? Video after the break.

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Mirror, Mirror On The Wall, Do My Eyes Deceive Me After All

February 19, 2022 by Matthew Carlson 4 Comments

Say what you will about illusions, [Create Inc] has some 3D prints that appear to change shape when viewed in a mirror. For example, circles transform into stars and vice versa. A similar trick was performed by [Kokichi Sugihara] in 2016, where he showed circles that appear as squares in the mirror. For the trick to work, the camera’s position (or your eye) is important as the shapes look different from different angles. The illusion comes in when your brain ignores any extra information and concludes that a much more complex shape is a simpler one. [Create Inc] walks you through the process of how the illusion works and how it was created in Blender.

When he posted the video on Reddit, most seemed to think that it wasn’t a mirror and there was some camera trickery. At its heart, this is reverse-engineering a magic trick, and we think it’s an impressive one. STL files are on Thingiverse or Etsy if you want to print your own. We covered a second illusion that [Kokichi] did that relies on a similar trick.

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