Oct 18, 2015 | By Benedict

An Imgur and Reddit user going by the name of NSA_Listbot has created what might be the world’s first portable, 3D printed railgun. The amateur arms-maker detailed the construction process on a lengthy Imgur post.

Rather than rely on gunpowder to propel ammunition, a railgun is comprised of a large electric circuit, made up of three main parts: a power source, two parallel rails (one positively conducting, one negatively), and a moving armature. An electric current flows from the the power supply, up the positive rail, across the armature, and down the negative rail, before returning to the power supply. A magnetic field is generated, which is directed vertically between the two rails, and the railgun’s projectile is acted upon by the Lorentz force, in the direction of the current flowing across the armature.

NSA_Listbot’s railgun, which uses six 300J, 350V, 5500uF capacitors with a combined weight of 20lbs, can deliver >1050V and 1.8kJ of energy to a projectile. The device can fire copper plated tungsten, aluminum, carbon and teflon/plasma, at speeds of 250m/s.

To build the railgun, NSA_Listbot wired the capacitors in parallel with flexible busbars inside of a custom-made, 3D printed housing. All of the 3D printed parts of the railgun were printed in ABS plastic. On the frame sits an emergency discharge SCR, power resistor and discharge button, for discharging any leftover energy in the caps after a shot has been fired.

The maker employed an Arduino Uno R3 to handle the electronics of the railgun, which monitors the capacitor voltage, amperage, temperature and battery voltage. A 12V LiPo battery is stepped up to 120V using a micro-inverter, then to 1550V through a transformer before it is rectified. A heatsink was mounted to the exterior to reduce heat.

Pressure regulators are located in railgun’s handle. The pneumatic system draws CO2 from a paintball gun tank into a compressed gas tank in the middle of the railgun.

The railgun is comprised of a set of outer rails and inner rails. The aluminium outer set is non-replaceable, but are invulnerable to rail erosion. The copper inner rails are designed to be periodically replaced. These inner rails are held in place by a polycarbonate muzzle break. The polypropylene injector is free to slide in and out once the muzzle break is removed.

So just how effective NSA_Listbot’s creation? Its 250m/s firing speed is not to be scoffed at. A standard handgun round does around 350m/s. Although less devastating, the 3D printed railgun is ultimately a scaled down version of the kind of weapon being developed by the US Navy. That military device can launch a 23lb projectile at over 2,200m/s.

CAD design, 3D printed parts in grey. Images from Imgur.



Posted in 3D Printing Application



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Joe wrote at 10/20/2015 4:42:47 AM:

What's the actual muzzle energy?

Stephen M. Paraski wrote at 10/19/2015 8:28:46 PM:

Brilliant home spun Engineer. Remember Henry Ford started in his "carriage" house in Detroit.

Comedicles wrote at 10/19/2015 7:49:54 AM:

Muzzle brake.

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