Victorian Train Tunnel Turned Test Track

June 4, 2023 by Danie Conradie 28 Comments

Characterizing the aerodynamic performance of a vehicle usually requires a wind tunnel since it’s difficult to control all variables when actually driving. Unless you had some kind of perfectly straight, environmentally controlled, and precision-graded section of road, anyway. Turns out the Catesby Tunnel in the UK meets those requirements exactly, and [Tom Scott] recently got to take a tour of it.

The 2.7 kilometer (1.7 mile) long tunnel was constructed as a railway tunnel between 1895 and 1897, thanks to the estate owner objecting to the idea of “unsightly trains” crossing his property. The tunnel’s construction was precise even by modern standards, deviating only 3 mm from being perfectly straight along its entire length. It lay abandoned for many years until it was paved and converted into a test facility, opening in 2021.

To measure the speed without the luxury of GPS reception, a high-speed camera mounted inside a vehicle detects reflective tags mounted every 5 m along the tunnel’s wall. This provides accurate speed measurement down to 0.001 km/h. A pair of turntables are installed at the ends of the tunnel to avoid an Austin Powers multi-point turn (apparently that’s the technical term) when turning around inside the confined space.

Due to the overhead soil and sealed ends, the temperature in the tunnel only varies by 1 – 2 °C year round. This controlled environment makes the tunnel perfect for coastdown tests, where a vehicle accelerates to a designated speed and then is put into neutral and allowed to coast. By measuring the loss of speed across multiple runs, it’s possible to calculate the aerodynamic drag and friction on the wheels. Thanks to the repeatable nature of the tests, it was even possible to calculate the aerodynamic losses caused by [Tom]’s cameras mounted to the outside of the vehicle.

The Catesby Tunnel is an excellent example of repurposing old infrastructure for modern use. Some other examples we’ve seen include using coal mines and gold mines for geothermal energy.

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The Most Ornate Birdbath You’ve Ever Seen

June 4, 2023 by Danie Conradie 8 Comments

When one thinks of art, a birdbath may not be the first thing that comes to mind. However, there is no denying that the La Fontaine aux Oiseaux (The Bird Fountain) is a true work of art. This automaton, created by automaton maker [François Junod] in collaboration with 20 different workshops and craftsmen, represents thousands of hours of work and boasts a complex beauty that is both visible and hidden.

Commissioned by the Van Cleef & Arpels jewelry company, this purely mechanical display piece features a pair of jewel-encrusted birds that perform a little routine around the edge of the bath every hour. All the birds’ appendages move while bird song is added with the help of a whistle and bellows. The “water” is also mechanized, with a series of metal plates moving together to create ripple effects, while a water lily opens and closes and a dragonfly flutters above the surface.

The overall effect of this ridiculously over-the-top mechanical art piece is absolutely mesmerizing. Even if the bejeweled exterior isn’t quite your style, you can still appreciate its intricate workings thanks the video after the break giving us a peek at the development.

We’ve featured some of [François]’ other work before, which is equally impressive and displays the mechanics in all it’s glory. If you want to try your hand at making automatons, 3D printing is the perfect way to get started.

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A Simple Guide To Cams

May 31, 2023 by Danie Conradie 10 Comments

With the availability of precision controllable actuators, it’s easy to overlook the simple but versatile mechanisms that got us here. In the video after the break, [Teaching Tech] explores the basics of cams and how to use them in your projects.

Cams are used to convert rotation into linear motion, and are probably best known for their use in engines and locking mechanisms. [Teaching Tech] first goes over the basic design and terminology in CAD, and demonstrates it’s use with a cam follower, locking mechanism, cam plate, and a knob that snaps to predefined positions. Of course a cam shape is not limited to a single lobe, but can have multiple lobes of various heights to create different motion patterns.

Cams are especially useful when you need to operate multiple mechanisms from a single input drive, as [Teaching Tech] demonstrates with the 3D printed automaton of a polar bear attempting to swipe a seal. We’ve also seen cams on a mechanical 7-segment display, and they were used to safely fire machine guns through aircraft propellers up to the 1950’s.

So next time you’re thinking adding another actuator to a project, take a moment to consider if a cheap and simple cam could do the job.

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Hackaday Prize 2023: Low Cost Braille Embosser From 3D Printer Parts

May 31, 2023 by Danie Conradie 8 Comments

The limited availability of texts transcribed to Braille and the required embossing equipment is a challenge world wide, but especially in poorer countries. To alleviate this problem, a team makers from in Cameroon have been developing BrailleRAP, an open source Braille embosser.

BrailleRAP is built built using commonly available 3D printer components, printed parts, and a laser-cut acrylic or wood frame. Paper is fed between a pair of carriages, the bottom one punching dots with a solenoid while the other acts as the anvil. Sheets of paper are fed in one or two at a time with stepper controlled rollers to control the position. At a cost of about $250, it is about a tenth of the price of the cheapest commercial solution, and the team have created excellent documentation so anyone can build it.

BrailleRAP was inspired by BRAIGO, another Hackaday-featured embosser assembled LEGO Mindstorm parts. We also featured another simple, but ingenious handheld embosser for portable use.

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DIY 3D Printed Rain Gauge Connects To Home Assistant

May 30, 2023 by Danie Conradie 16 Comments

Measuring local rainfall has real practical uses, especially in agriculture, but most of us will have to admit that it’s at least partly about drawing cool graphs on a screen. Whatever your motivation, you can build this open source electronic rain gauge designed by [Sebastian] of Smart Solutions for Home, and integrate it with Home Assistant.

This 3D printed rain gauge is of the ubiquitous tipping bucket type and uses a magnet and hall effect sensor to detect every time the bucket tips out. The sensor is soldered to a custom PCB with ESP32 configured using ESP Home. By keeping it in deep sleep most of the time and only waking up when the tip of the bucket, [Sebastian] estimates it can run about a year on four AA batteries, depending on rainfall. The hinge mechanism is adjustable to ensure that both buckets will tip with the same volume of water.

FDM 3D printed enclosures are not known for being waterproof, so [Sebastian] coated the PCB with varnish to protect it from moisture. This worked well enough that he could leave it running in a bowl of water for a few hours without any ill effects. The end result looks good and should be able to handle the outdoors for a long time.

Building a weather station is a popular DIY project. Some of the interesting varieties we’ve seen are powered by supercapacitors, show readings on antique analog dials and convert parking distance sensor kit into a wind gauge.

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Automate Handwritten Postcards With Robots

May 29, 2023 by Danie Conradie 15 Comments

As someone notorious for not doing things the old-fashioned manual way, we’re not sure by [Shane] of Stuff Made Here was thinking when he promised to send out a few hundred handwritten letters. Predictably he built an automated production line for the task. Video after the break.

With “handwritten” and “automated” not being particularly compatible, [Shane] set out to create a robot to create believable handwritten letters, which is significantly harder than it may seem at first glance. It turns out that turning your handwriting into a font is too consistent to be believable, which led down the rabbit of generated handwriting. [Shane] first spend a ridiculous amount of time trying to implement a machine learning model for the task, only to find there’s already an open source library good enough to fool a forensic handwriting expert.

On the robot side, [Shane] used a pen plotter from Amazon that’s it’s actually cheaper than building one from scratch. With the “handwriting” taken care of, [Shane] set up an automated loading system with the industrial robot arm he also used for his CNC chainsaw. The feeders for the empty and full postcards are 3D printed with a spring-loaded mechanism to keep the top card at the same height all the time.

Although this project contained less custom hardware and software than [Shane’s] other projects, it served as an excellent reminder that it’s unnecessary to reinvent the wheel when building a car. It’s easy to get caught up in the small details of a project that don’t matter much in the final implementation and usage.

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The Fascinating Evolution Of Micromouse

May 28, 2023 by Danie Conradie 15 Comments

You would think there are only so many ways for a robotic mouse to run a maze, but in its almost 50 year history, competitors in Micromouse events have repeatedly proven this assumption false. In the video after the break, [Veritasium] takes us on a fascinating journey through the development of Micromouse competition robots.

The goal of Micromouse is simple: Get to the destination square (center) of a maze in the shortest time. Competitors are not allowed to update the programming of their vehicles once the layout is revealed at the start of an event. Over the years, there have been several innovations that might seem obvious now but were groundbreaking at the time.

The most obvious first challenge is finding the maze’s center. Simple wall following in the first event in 1977 has developed into variations of the “flood fill” algorithm. Initially, all robots stopped before turning a corner until someone realized that you could cut corners at 45° and move diagonally if the robot is narrow enough. The shortest path is not always the fastest since cornering loses a lot of speed, so it’s sometimes possible to improve time by picking a slightly longer router with fewer corners.

More speed is only good if you can keep control, so many robots now incorporate fans to suck them down, increasing traction. This has led to speeds as high as 7 meters/second and cornering forces of up to 6 G. Even specks of dust can cause loss of control, so all competitors use tape to clean their wheels before a run. Many winning runs are now under 10 seconds, which require many design iterations to increase controllable speed and reduce weight.

All these innovations started as experiments, and the beauty of Microhouse lies in its accessibility. It doesn’t require much of a budget to get started, and the technical barrier to entry is lower than ever. We’ve looked at another Micromouse design before. Even if they aren’t micromice, we can’t get enough of tiny robots.

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