Full-Auto Crossbow Rocks and Rolls on Rubber Bands and Electric Drill

You’ve got to enjoy any project where the hacker clearly loves what he or she is doing. And when the project is as cool as a motor-driven, rubber band powered, fully automatic crossbow, it’s hard not to laugh along.

A full-auto crossbow is no mean feat, and it took a man with a love for rubber-powered firearms to get it right. [JoergSprave]’s design is based on a rack-and-pinion system and executed mainly in plywood. The main pinion gear is a composite of aluminum and wood, in a bid to increase the life of the mechanism and to properly deal with the forces involved. The pinion, turned by a powerful electric drill, drives the rack back and locks the carrier under the 30-bolt magazine. A rubber-powered follower forces a bolt down and a cam on the pinion trips the sear, the bolt is fired and the cycle continues.

We slowed the video down a bit and it looked to us like the cyclical rate of fire was about 7 rounds per second, or a respectable 420 rounds per minute. Pretty powerful, too, and the accuracy isn’t bad either.

We’ve seen [Joerg]’s inventions before, like this soda bottle Gatling arrow launcher, or his ridiculous machete launcher. We hope he keeps having fun and letting us watch.

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Disposable Camera Coil Gun!

Some of the most enjoyable projects tend to have the terrible drawback of also having the most potential to cause bodily harm, like getting zapped by the capacitor when digging into a disposable camera. But often — if you’re careful — this curiosity pays off and you wind up learning how to make something cool like this coil gun from a camera flash’s capacitor. This handheld launches a small nail, and is packed in a handheld form factor with a light switch trigger.

[LabRatMatt] dispels any illusions of potential harm upfront and then repeatedly urges caution throughout his detailed guide. He breaks down the physics at work while maintaining a lighthearted tone. This coil gun uses a capacitor and charging circuit ripped from a disposable camera — [LabRatMatt] decided to double up with another capacitor that he had on hand from a previous project. The coil was repurposed from an old doorbell, but make sure to use a few hundred windings if you make your own coil. A light switch ended up being suitable for a trigger since it is able to handle the voltage spikes.

When assembled, it almost looks like something you’d expect to see in a post-apocalyptic wasteland, but it works!

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A DIY Net Gun To Catch Whatever You Want

Suspicious drones hovering about your property? Burglars or other ne’er-do-well test subjects giving you trouble? Need to catch a dog that keeps meandering through your workshop? [William Osman] suggests you build yourself a pneumatic net gun that can shoot 20-30 feet to catch them all.

The net gun is built largely out of PVC pipe; the air tank — filled via a tire valve — uses adapter fittings to shrink it down to a 1″ sprinkler valve, with an air gun to act as a trigger. The net launcher is made of four lengths of pipe bent with the use of a heat gun — an Occam’s Razor solution compared to his first attempt — and is coupled to the end, while the net loads in using wooden dowels with washers as weights. It won’t trap any large game, but it will certainly net you some fun.

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The Potowitzer: A Rapid Fire Potato Cannon

If you’ve ever fired a potato cannon, you’ll know that they are a raucous good time, but are somewhat clumsy to reload after each shot. Seeing an opportunity to improve on the design and minimize the delay between launches, [Danger First] have concocted a fast reloading potato cannon — or should I say — Potowitzer.

The key here is that they’ve gone through the extra effort of designing and building honest-to-goodness artillery rounds for their Potowitzer’s manual breech-loading mechanism. Foregoing the inconsistency of potatoes, they’ve 3D printed a bevy of bullets and sealed them with propane gas into PVC pipe cartridges. Metal contacts around the base to carry current from a BBQ lighter to the inside of the cartridge to ignite the propellant. Seeing it fire at about 18 rounds per minute is something special.

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Building The Brightest Light Sabre In The World

If you are looking for a Star Wars light sabre, sometimes your choices can be a little disappointing. “Replica” sabres from toy and novelty vendors may superficially look the part, but with their tinny speakers and lacklustre show of LEDs they often have less of the Force about them and more of the Farce.

[Jeremy Lee] offers a solution; he’s built what he claims to be the brightest light sabre in the world. That’s a bold assertion, and one which we think might even throw down a gauntlet to other sabre builders and spark an arms race among Jedi wannabes.

The super-bright sabre uses a 144 LED double-sided strip of Neopixels in a polycarbonate tube, with a DC to DC converter powered by a 1000mAH LiPo battery. Sound effects come from a SparkFun Pro Micro powering a 2W speaker through a small audio amplifier. The handle meanwhile is constructed from PVC pipe fittings.

His first attempt at the sabre had the LEDs at full power, and promptly melted his tube. Thus the final version runs at 40% of its maximum rating, with a “burst” mode for those moments at which combat demands it.

His write-up is a series of posts, with plenty of video at all points. It might seem odd to show you the shortest of them here at only a few seconds long, but since the unique selling point is its brightness we think the best way to show that is at night.

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Trio of Magnetrons Power a Microwave Rifle

Can you build a working EM weapon from three microwave ovens? Apparently, yes. Should you do so? Maybe not when the best safety gear you can muster is a metallized Mylar film fetish suit and a Hershey’s Kiss hat.

Proving that language need not be a barrier to perfect understanding of bad ideas, the video below tells you all you need to know, even without subtitles in the non-Russian language of your choice. [KREOSAN]’s build is obnoxiously obvious — three magnetrons mounted on a tin can “resonator” with a foil-covered waveguide at the business end. The magnetrons are tickled by a stun-gun that’s powered by a pack of 18650 batteries. The video shows some “experiments”, like lighting up unpowered CFL bulbs from about 15 meters away and releasing the Blue Smoke from the electrical system of a running motor scooter. Assuming they weren’t added in post, the artifacts in the video belie the gun’s lack of shielding for the operator. We doubt any of the ad hoc safety gear would provide any protection from the resulting microwaves, but we also doubt that it matters much when things have gotten this far.

We’re not too sure about this one — some of the zapping stunts look a little too conveniently explosive. It’s hard to tell the details without a translation, so maybe one of our Russian-speaking readers can pitch in on the comments. Although this isn’t [KRESOAN]’s first microwave rodeo, having melted a few lightbulbs with magnetrons before. Even seeing this we still consider EMP Weapons a figment of Hollywood’s imagination.

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Minecraft Sword Lights Up When Nearby Friends

With All Hallow’s Eve looming close, makers have the potential to create some amazing costumes we’ll remember for the rest of the year. If you’re a fan of the hugely addict-*cough* popular game Minecraft, perhaps you’ve considered cosplaying as your favorite character skin, but lacked the appropriate props. [Graham Kitteridge] and his friends have decided to pay homage to the game by making their own light-up Minecraft swords.

These swords use 3D-printed and laser-cut parts, designed so as to hide the electronics for the lights and range finder in the hilt. Range finder? Oh, yes, the sword uses an Arduino Uno-based board to support NewPixels LEDs and a 433Mhz radio transmitter and receiver for ranged detection of other nearby swords that — when they are detected — will trigger the sword to glow. Kind of like the sword Sting, but for friendlies. Continue reading “Minecraft Sword Lights Up When Nearby Friends”