Supersonic NERF Dart Speedometer

ATtiny Chronograph

[John] was faced with an interesting problem: after he built his own air cannon, how could he tell exactly how fast his NERF darts were moving? Luckily he had some spare parts on hand and hacked together a fully functional projectile speedometer for less than the cost of an Arduino.

A device is essentially two detectors spaced a precise distance apart from one another. When something passes the first detector, a timer is activated which measures how long it takes the object to reach the second detector. From this, the device calculates the speed. [John] used infrared emitter/detector pairs spaced exactly three inches apart and wired them to an ATtiny2313. After a little bit of coding, he now knows just how fast he can fire those squishy ballistic missiles.

The infrared emitter/detector pairs are mounted to a PVC pipe through which the projectile travels. [John] notes that in theory this could be used to measure almost anything that could fit through the pipe, although this particular device might be damaged by muzzle flash or a pressure wave from an actual gun.

We’ve seen other NERF dart air cannons before, and we wonder if maybe there should be some sort of competition to see who can shoot a NERF dart the fastest now that there’s an easy way to measure speed?

 

Homemade Bazooka Has Earned Its Stripes

Many of us dream of launching rockets from our shoulders, but [John] here actually did something about it.

This bazooka build started with a 6″ diameter PVC pipe. He mounted a length of 80/20 T-slotted aluminum extrusion to the pipe through a couple of wood blocks. [John] installed rail buttons on some Estes Alpha rockets which slide along nicely inside the T-slot. He welded a PVC cleanout fitting and plug to one end for easy access and gave her a nice paint job.

The ignition is simple: an irresistible red push button is wired to a 9V battery and a pair of alligator clips. [John] loads up a rocket, puts the gators on the wires of an igniter, pushes said button, and Bob’s your uncle. All he needs now is a pair of gun boats. Video of the build and some demonstrations we don’t necessarily recommend are after the jump.

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Bicycle Wheel Bow Has Plenty of Kick

bicycle bow

Here’s a clever way to recycle and reuse an old bicycle wheel! [Darren] came up with this idea a while ago, and unable to find any mention of it on the internet, he decided to make his own — He calls it the Bike Wheel Bow.

Now technically it may look like a bow, but it’s actually more of a bow-like-sling-shot, as it relies on stretch of the string (which is rubber tubing) instead of the bow itself — regardless though, it’s a cool piece of kit.

[Darren] chopped up a bicycle wheel, removed the spokes, and was left with a nice semi circle. Using regular old eyelets he installed them around the perimeter giving it a bit of a compound bow look. He’s using rubber medical tubing with a section of bicycle inner-tube in the middle which provides a fold, allowing you to shoot arrows without knocks. You can use the inner-tube for the whole thing, but it’s not as powerful.

For a bow made out of almost entirely recycled parts, it’s pretty good — he’s even made an arrow rest using the hub and a bent spoke. The only caveat to the design is the rubber tends to stick on the eyelets — it’s best to lube them up a bit before shooting. Alternatively a few $1 pulleys might work even better!

If you’re looking for a more traditional home-made bow build, why not use a pair of cross country skis? Or if you’re alone in the woods, make one completely from scratch!

Firing Blanks With Laser Tag

glockLast year, [Tony] was asked to develop a lasertag system with ultimate realism. This meant a system that used a blank firing replica gun, and a system to detect blank rounds being fired. Very cool, and the way he went about it includes some interesting electronics.

Because the system requires a blank to be fired before shooting a laser at a target, the entire system must be able to detect a blank being fired. [Tony]’s first attempt used a piezo sensor to detect the shock from being fired. This system had a lot of noise and was ditched for a much better solution: a magnet mounted to the slide, and a hall effect sensor mounted to a 3D printed frame that turns this replica into a carbine.

A little bit of tweaking in software was required to inhibit the laser when the operator cocks the gun, but it looks – and sounds – really good. It’s also very, very realistic: the only way to shoot an opponent is to physically reload. Video below.

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[Furze] Sets Fire to Everything with Pyro Gloves

Pyro Build

Crazyman [Colin Furze] is back, and this time he’s setting everything on fire with his Pyro gloves. Though Hackaday readers are already a discerning bunch, this is a build we get submissions for all the time and feature fairly often. It would take an exceedingly impressive build to outshine the other fire hazards. But, as with his pneumatic Wolverine claws and his electromagnetic boots, [Furze] knows how to build the insane and then put on a good show.

The Pyro build is part of [Furze’s] 3-part celebratory X-Men extravaganza, a nod to the realm of superheroes coinciding with the release of the new X-Men film. [Furze] began with a custom reservoir cylinder that fitted with two solenoid valves: one for a pilot light and another for the big blasts. He’s also affixed a Piezo element and a AA battery, which sits in a cozy little container. The bulkier bits of the assembly sit in a backpack, hooking up, as expected, to the wrist-mounted devices. This flame cannon, however, is unique among the ones we’ve encountered here.

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Pneumatic Wolverine Claws Are Quite Possibly The Best Thing Ever

With the new X-Men movie coming out soon, [Colin Furze] decided to make some real working props from the movies — starting with some bloody brilliant fully functional and retractable Wolverine claws.

We’ve seen Wolverine claws before, even electrified Wolverine claws, but never have we seen anyone take them to the level [Colin] has. He didn’t just want realistic Wolverine claws. He didn’t just want claws that could deploy. He wanted realistic claws that could both deploy, and retract — fast! And he wanted them to branch out just like the real deal.

He started brainstorming different ways of doing this. Motors, springs, geared racks, cables, pneumatic cylinders… nothing really fit the bill. Pneumatic power seemed the best option for performance, but the problem is he’d need a 12″ cylinder to sit behind his claws — it’d completely ruin the look — one of his main criteria for the project.

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Electromagnetic Spiderman Webshooter Railgun / Grappling Hook

spiderman grapple hook rail gun

As technology continues to advance, make-believe props and technology from movies are coming closer and closer to reality. [Patrick Priebe] has managed to put together a working Spiderman Webshooter with the help of electromagnets!

He’s built a tiny coil gun that puts out 100 Joules of energy using a 350V capacitor bank, which straps cleanly to his wrist over top of a Spiderman costume glove. It makes the classic high-pitched hum as it charges, and launches a small barbed brass arrow capable of skewering Styrofoam.

He didn’t stop there though! He’s created a handy little winch using a small high-powered brushless motor with an ESC. A weighted disk acts as a flywheel to increase the pulling power of the fishing line, and he’s built it on a pivot so when you launch it, the fishing line just slips off the end without resistance. To engage, you flip it back perpendicular to the line and turn on the motor.

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