Semi-Automatic Rail Gun is a Laptop Killer

It’s huge, it’s unwieldy, and it takes 45 seconds to shoot all three rounds in its magazine. But it’s a legitimate semi-automatic railgun, and it’s pretty awesome.

Yes, it has its limits, but every new technology does, especially totally home-brew builds like this. The aptly named [NSA_listbot] has been putting a lot of work into his railgun, and this is but the most recent product of an iterative design cycle.

The principle is similar to other railguns we’ve featured before, which accelerate projectiles using rapidly pulsed electromagnets. The features list in the video below reads like a spec for a top-secret military project: field-augmented circular bore, 4.5kJ capacitor bank, and a custom Arduino Nano that’s hardened against the huge electromagnetic pulse (EMP) generated by the coils. But the interesting bits are in the mechanical design, which had to depart from standard firearms designs to handle the caseless 6 mm projectiles. The resulting receiver and magazines are entirely 3D printed. Although it packs a wallop, its cyclic rate of fire is painfully slow. We expect that’ll improve as battery and capacitor technology catches up, though.

Want to check out some more railgun builds? We’ve got them in spades — from one with $50,000 worth of caps to a wrist-mounted web-slinger.

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Coil Gun for Newbies: Learning Electromagnetic Propulsion

There’s something attractive about coil guns, especially big ones. It’s probably the danger; between the charge stored in banks of capacitors and the flying projectiles, big coil guns can be lethal to experiment with. But there is a lot to be learned from how coil guns work, especially if you build this 3D-printed entry-level coil gun.

For the coil gun newbie, [Great Scott] does a fantastic job of explaining the basics. Pulsing the coil at just the right time will suck a ferromagnetic projectile into the coil core and let momentum fling it out, and multiple coils used correclty improve performance.

His gun is a simple pistol design with two coils, optical sensors to tell when the projectile is centered in each coil, and an Arduino to coordinate everything. The results are not spectacular — he uses only a modest amount of current — but the gun still works. [Great Scott] points out how a capacitor bank could be used to increase the current, but for the sake of keeping it simple he leaves that as an exercise for the builder.

Many coil gun and rail gun builds have made it to our pages over the years, including his ridiculously powerful gun that uses a capacitor bank so large it needs its own car. We like this build for its simplicity, its approachability, and the excellent explanation of its function.

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The Most Powerful DIY Railgun

The US Navy is working on a few railgun projects that will eventually replace the largest guns on the fleet’s cruisers and destroyers. These rail guns will fire a projectile away from the ship at around Mach 7 on a ballistic trajectory to a target one hundred miles away. It’s an even more impressive piece of artillery than a gun with a nuclear warhead, and someday, it will be real.

most-powerful-non-military-railgunUntil then, we’ll have to settle with [Zebralemur]’s DIY mobile railgun. He built this railgun capable of firing aluminum projectiles through pumpkins, cellphones, and into car doors and blocks of ballistics gelatin.

All rail guns need a place to store energy, and in all cases this is a gigantic bank of capacitors. For this project, [Zebralemur] is using fifty-six, 400 Volt, 6000 microfarad caps. The MSRP for these caps would be about $50,000 total, but somehow – probably a surplus store – [Zebralemur] picked them up for $2,400.

These caps are just the power supply for the rail gun, and aren’t part of the structure of this already large, 250 pound gun. Luckily, with the seats down in [Zebralemur]’s car, they fit in the back of his hatchback.

These caps are charged by a bunch of 9V batteries stuck end to end. When the caps are charged, all the power is dumped into two copper bars in the gun, accelerating the aluminum projectile to speeds fast enough to kill. It’s an incredible build, but something that should not be attempted by anyone. Although this does seem to be the year that all danger seekers are busting out their electromagnetic projection flingers.

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3D Printed Gun is Off the Rails

There are certain topics that cause people to have knee-jerk reactions: Try asking a crowd which Star Trek was best or–around here–take a stance for or against the Arduino and you’ll see what we mean. Certainly people polarize quickly when you talk about a 3D printed gun. However, if anyone can sneak [xtamared’s] 3D printed rail gun through airport security, then some guards will have to be fired. It looks like a cool prop from a bad movie, but (as you can see in the videos below) it can project a conductive slug into a decidedly low-tech target.

There aren’t many build details, although you can deduce a few things from the pictures and the captions. At the rear of the gun is a paintball tank that gets the slug moving before it hits the rails which further accelerate the projectile. The electric part is Arduino-based and the very prominent capacitors at the front end can deliver 1800 joules of energy (and add 20 pounds of weight to the gun).

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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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Building a Rail Gun

[Valentin] tipped us about his latest project: a homemade railgun. For the few that may not know already, a railgun is an electrically powered electromagnetic projectile launcher. It is comprised of a pair of parallel conducting rails, along which a sliding armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail. [Valentin]’s writeup starts with a detailed explanation of this principle, then a simple proof of concept is shown where a metal stick with two small round magnets on each end is accelerated along two alumium strips powered by a 9V battery.

The final build shown above is powered by a capacitor bank consisting of three 400V 2200uF capacitors in parallel. [Valentin] opted for a hot rail design, where the power is always present on the rails. The projectile is inserted into the assembly by a spring-loaded lever. A video is embedded after the break. If you found this interesting, you’re going to love the fully-automatic Gauss gun.

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My what a large capacitor bank you have

[Daniel Eindhoven] put together this 11,344 Joule capacitor bank that he says would be perfect for weapons such as a rail gun, coil gun, or electrothermal-chemical gun. He machined a couple of aluminum plates to act as a positive and negative bus. The two are separated by a denuded sheet of PCB (making us wonder how he got the copper to peel off like that). Once charged there’s the little problem of how to discharge the system without getting bit, which [Daniel] solved by building a pneumatic switch. We didn’t find the test-fire footage very interesting but we did embed the demonstration of his switch after the break.

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