3D Printed Rigid Chain Mechanism

December 8, 2020 by Danie Conradie 34 Comments

One of the major advantages of 3D printing is the ability to quickly test and then iterate on mechanical designs. [gzumwalt] does a lot of this, and has recently been working on various versions of a rigid chain mechanism. (Video, embedded below.)

A rigid-chain mechanism is one way of fitting a long beam into a small box. It works similar to a zipper, meshing two separate “chains” with specially teeth designed to form a rigid beam. Due to clearances between the teeth, the beam tends to be a bit floppy. [gzumwalt] made various sizes of the mechanism, and also reduced the clearances on later versions to reduce the flop. He also integrated it into a cool “snake in a basket” automaton (second video below) by adding a reversible gearbox and a binary snap-action switch.

One possible use for this type of mechanism is for autonomously assembling long structures in space, as one of the 2017 Hackaday Prize finalist projects, ZBeam, proposed.

[gzumwalt] has not made the files available for download yet, but you can keep and eye on his Instructables pages for updates. He got a number of fascinating 3D printed devices already available, like a domino laying machine or a WiFi controlled rover.

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Tiny Chain-Link Fence Made With Hand-Cranked Brilliance

December 6, 2020 by Danie Conradie 24 Comments

Chain link fences are woven with a mechanism that is almost hypnotic to watch, so [Levsha] decided to build his own tiny hand-crank tabletop version to make tiny copper wire fences.

Chain link consist of a series of wires bent and woven in a zigzag pattern. The zigzag bends are made by winding the wire around a rotating flat plate inside a stationary tube with a spiral slot in the side to keep the spacing of the bends consistent. [Levsha]’s version is roughly 1/10 scale of the real thing, and only does the bending and winding parts. Linking the bent wire together is up to the operator. All the components were machined on a lathe and CNC router, and beautifully finished and assembled on a wood base. The hardest part was the tube with the spiral slot, which took a few attempts to get right. [Levsha] initially tried to use steel wire, but it was too stiff and caused the winding mechanism to lock up. 0.4 mm copper wire turned out to be the best choice.

Although there is no practical use for this device that we can see, the craftsmanship is excellent, and it is one of those videos that reminds us how badly we want some machine tools.

Fine attention to detail is really what makes videos like this enjoyable to watch. Wee seen a few other such project, like a beautiful scratch-built lathe, or a pneumatic powered drone that can’t fly.

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A Rocket Powered Ejection Seat For Model Aircraft

November 21, 2020 by Lewin Day 4 Comments

As radio control planes don’t typically have human pilots onboard, the idea of installing an ejection seat in one is somewhat frivolous. But that doesn’t mean it wouldn’t be a lot of fun, and [James Whomsley] has set his mind to achieving the task.

The build process is an iterative one, with [James] solving problems step-by-step and testing along the way. The first task was to successfully launch a small action figure and his flight seat vertically in a controlled fashion. After a few attempts, a combination of rocket motors and guide rails were settled upon that could achieve the goal. Next up, a drogue parachute system was designed and tested to stabilize the seat at the height of its trajectory. Further work to come involves handling seat separation and getting the action figure safely back to the ground.

While action figures aren’t alive and the ejection seat serves no real emergency purpose, we can imagine it would be a hit at the local flying field – assuming the parachutes don’t get tangled in someone else’s model. For those interested in the real technology, our own [Dan Maloney] did a great piece on the topic. Video after the break.

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ESP8266 Does RC Without The Transmitter

October 30, 2020 by Tom Nardi 27 Comments

While the cost of a hobby-grade remote control transmitter has dropped significantly over the last decade or so, even the basic models are still relatively expensive. It’s not such a big deal if you only need to get one for personal use, but for a school to outfit a classroom’s worth of students their own radios, they’d need to have a serious STEM budget.

Which is why [Miharix], himself an educator with a decade of experience, developed a project that leverages the ESP8266 to create affordable RC vehicles that can be controlled with a smartphone’s web browser. There’s a bit of irony at play since the smartphones are more expensive than the RC transmitters would have been; but with more and more school-age kids having their own mobile devices, it takes the cost burden off of the educators. Depending on the age of the students, the teacher would only need to keep a couple of burner phones on hand for student that doesn’t have a device of their own.

A custom PCB makes connections easier for students.

In its fully realized form, the project uses an open hardware board that allows standard RC hobby servos to be connected to the GPIO pins of a ESP-12E module. But if you don’t want to go through the trouble of building the custom hardware, you could put something similar together with an ESP development board. From there it’s just a matter of installing the firmware, which starts up a server providing a touch-based controller interface that’s perfect for a smartphone’s screen.

Since the ESP8266 pops up as an Access Point that client devices can connect to, you don’t even need to have an existing network in place. Or Internet access, for that matter. [Miharix] says that in tests, the range between a common smartphone and the ESP8266 is approximately 85 meters (260 feet), which should be more than enough to get the job done.

In the videos after the break you can see this system being used with an RC car and boat, though the only limit to what you could control with this project is your own imagination.

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Greeking Out With Arduinos

September 18, 2020 by Brian McEvoy 4 Comments

Learning a new language is hard work, but they say that the best way to learn something is to teach it. [Angeliki Beyko] is learning Greek, and what better way to teach than to build a vocabulary flash-card game from Arduinos, color screens, 1602 text screens, and arcade buttons? After the break, we have a video from the creator talking about how to play, the hardware she chose, and what to expect in the next version.

Pegboard holds most of the hardware except the color screens, which are finicky when it comes to their power source. The project is like someone raided our collective junk drawers and picked out the coolest bits to make a game. Around the perimeter are over one hundred NeoPixels to display the game progress and draw people like a midway game. Once invested, you select a category on the four colored arcade buttons by looking at the adjacent LCD screens’ titles. An onboard MP3 shield reads a pseudo-random Greek word and displays it on the top-right 1602 screen in English phonetics. After that, it is multiple choice with your options displaying in full-color on four TFT monitors. A correct choice awards you a point and moves to the next word, but any excuse to mash on arcade buttons is good enough for us.

[Angeliki] does something we see more often than before, she’s covering what she learned, struggled with, would do differently, and how she wants to improve. We think this is a vital sign that the hacker community is showcasing what we already knew; hackers love to share their knowledge and improve themselves.

Typing Greek with a modern keyboard will have you reaching for an alt-code table unless you make a shortcut keyboard, and if you learn Greek, maybe you can figure out what armor they wore to battle.

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Vacuum Dragster Uses Syringes For Propulsion

September 17, 2020 by Lewin Day 16 Comments

Atmospheric pressure is all around us, and capable of providing a great deal of force when used properly. As Otto Von Guericke demonstrated with his Magdeburg hemispheres over 350 years ago, simply removing air from a chamber to create a vacuum can have astounding results. More recently, [Tom Stanton] has used vacuum to power a small 3D-printed dragster.

In the dragster build, a typical plunger syringe is plugged at the end, and the plunger pulled back. Atmospheric pressure acts against the vacuum, wanting to push the plunger back towards its original position. To make use of this, a string is attached to the plunger, causing it to turn a gear as it moves forward, driving the rear wheels through a belt drive. With the correct gear ratio on the belt drive, the dragster is capable of spinning its tires and shooting forwards at a quick pace.

The work is a great follow on from [Tom]’s earlier vacuum experiments, using syringes as small rockets. It reminds us of the classic CO2 dragsters from high school competitions, and would be a great project for any science class. Video after the break.

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Toy O-Scope Is Dope

September 12, 2020 by Brian McEvoy 12 Comments

Not many of our childhood doll and action figure’s accessories revolved around lab equipment except maybe an Erlenmeyer flask if they were a “scientist.” No, they tended to be toasters, vehicles, and guns. When we were young, our heroes made food, drove sexy automobiles, and fought bad guys. Now that we’re older, some of our heroes wield soldering irons, keyboards, and oscilloscopes. [Adrian Herbez] made a scale model oscilloscope that outshines the beakers and test tube racks of yesteryear. Video also shown below. Continue reading “Toy O-Scope Is Dope” →