How to Make a Human Crossbow

Say you have a team of French engineers, a lake in the summer, a wizened old machinist, and some gigantic bungee cords. What would you build? The answer is clear, a human-launching crossbow. (Video, and making-of embedded below.)

the-human-crossbow-how-we-made-it-kim41mdcizymp4-shot0001You can start out watching the promo video because it looks like a lot of fun, but don’t leave without watching the engineering video. What looks like a redneck contraption turns out to be painstakingly built, and probably not entirely a death trap. The [Rad Cow] team even went so far as to purchase metal cart wheels.

Everyone else on the Intertubes would tell you not to do this at home. We say go for it. That is, draw up reasonable plans, work with an obviously competent machinist, and make something silly. It’s not going to be more dangerous than the stuff that [Furze] pulls off.

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The New York Public Library Built a Reading Railroad

What’s the best way to quickly move books from a vast underground archive to the library patrons who want to read them? For the New York Public Library (NYPL), it used to be an elaborate conveyor belt system. But the trouble with those is that the books will fall right off of them on a vertical run. What the NYPL’s gargantuan flagship library on 5th Avenue needed was a train to shuttle the books around. This week, as the majestic Rose Main Reading Room reopens after renovation, the train will leave the station.

From January to August 2016, workers retrofitted the existing conveyor belt infrastructure to support 950 feet of shiny, winding track. ‘Train’ is a bit of a misnomer because the cars travel singly. The double-track system traverses eight floors of library from the underground archive to any of the 11 designated stops. There are 24 book cars at present. Each one can hold about 30 pounds of books and travels at about 75 feet per minute.

In order to move between floors economically, some sections of track are completely vertical. How do the books stay in there? Simple—the cargo hold pivots on a gimbal. Sensors along the track make it easy to keep tabs on the cars, which are separated by a 15-second buffer to avoid collisions and mishaps. Click past the break for a sped-up demonstration. For you purists out there, we’ve also embedded the full, silent, real-time version that clocks in at nearly five minutes.

We like all kinds of trains around here, from the subterranean to the scientifically derailed.

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Real, Life-Sized Transformers

Ever dreamed of a real, life-sized Transformer in your garage? The Turkish startup Letrons now offers you exactly that: Their animatronic Autobot drives like a car, transforms like a Transformer, and supposedly fights off space threats with its built-in smoke machine and sound effects.

Letrons’s Transformer seems to be built upon a BMW E92 coupé chassis. According to the company, the beast is packed with powerful hydraulics and servo motors, allowing it to transform and move fast. Sensors all around the chassis give it some interactivity and prevent it from crushing innocent bystanders when in remote-control mode. Interestingly, its movable arms aren’t attached to the body, but to its extendable side-wings and feature hands with actuated wrists and fingers. The Autobot also can move its head, which pops right out of the hood.

Admittedly, Letrons must have spent a lot of time on the dark side of the moon and working in secrecy before they released footage of a working and polished prototype. It’s unclear if Letron’s Transformers will cooperate with the US military in solving armed conflicts, but they are certainly good for a show. Enjoy the video below!

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Hackaday Prize Entry: AutoFan Saves Tired Drivers With Face Recognition

Long distance driving can be tedious at times. The glare of the sun and the greenhouse effect of all your car’s windows make it hot and dry. You turn on the fan, or air conditioning if you have it, and that brings relief. Soon enough you’ve got another problem, the cold dry air is uncomfortable on your eyes. Eventually as you become more tired, you find yourself needing the air on your face more and more as you stay alert. You thus spend most of the journey fiddling with your vents or adjusting the climate controls. Wouldn’t it be great if the car could do all that for you?

AutoFan is a project from [hanno] that aims to automate this process intelligently. It has a fan with steerable louvres, driven by a Raspberry Pi 2 with attached webcam. The Pi computes the position of the driver’s face, and ensures the air from the fan is directed to one side of it. If it sees the driver’s blink rate increasing it directs the air to their face, having detected that they are becoming tired.

The build logs go into detail on the mathematics of calculating servo angles and correcting for camera lens distortion in OpenCV. They also discuss the Python code used to take advantage of the multicore architecture, and to control the servos. The prototype fan housing can be seen in the video below the break, complete with an unimpressed-looking cat. For those of you interested in the code, he has made it available in a GitHub repository.

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Retrotechtacular: Railroads In The Jet Age

The front of the Soviet jet train on a monument in Tver, Russia. By Eskimozzz [PD], via Wikimedia Commons.
The front of the Soviet jet train on a monument in Tver, Russia. By Eskimozzz [PD], via Wikimedia Commons.
It started with one of those odd links that pop up from time to time on Hacker News: “The strange and now sadly abandoned Soviet Jet Train from the 1970s“. Pictures of a dilapidated railcar with a pair of jet engines in nacelles above its cab, forlorn in a rusty siding in the Russian winter. Reading a little further on the subject revealed a forgotten facet of the rivalry between Russians and Americans at the height of the Cold War, and became an engrossing trawl through Wikipedia entries, rail enthusiast websites, and YouTube videos.

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Building An Electric Longboard From Scratch

Step one to most electric longboard builds is typically the acquisition of a foot operated longboard, with step two being the purchase of a ready-made motor bracket to electro-convert the strenuous vehicle. Not so [Matt Carl’s] scratch-built electric longboard, which starts out with four 1/8″sheets of baltic birch.

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A Motorcycle Lift From A Trailer Jack

If you have ever worked on a motorcycle on a regular basis with a limited workshop, you’ll know the challenge of taking off one or other of the wheels. You’ll probably have plenty of tales of bikes balanced precariously on blocks or suspended from the ceiling on a web of cargo straps, and if you are really unlucky you’ll have the Dented Tank Of Shame from the whole edifice tumbling down.

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