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).

It looks like a lot of the gun is printed in PLA, but the electronics case is ABS (doubtlessly to avoid exposing PLA to the heat sink attached to the 1500V rectifier). The paintball tank’s pressure gets the slug moving to 100 meters/second before it hits the rails. In early testing, a PLA part and a steel bolt broke, so the items got replaced with polycarbonate and nylon. Apparently, parts of the injector are polypropylene.

The rails themselves are made for replacement, since each shot damages them a bit. They are constructed of garolite (fiberglass and resin composite sort of like PCB material) and wrapped in carbon fiber. That’s one of the things that impressed us–this is a highly multimedia build with different materials used to do different jobs, digital and high voltage electronics, and pneumatics.

We’ve covered a lot of rail guns over the years and we’ve looked at robot-mounted coil guns, too. If you want something more portable, check out this tiny rail gun (although the Geocities cache for the article is dead, but there are others).

Thanks [caffeine_addict] for the tip!

22 thoughts on “3D Printed Gun Is Off The Rails

    1. Yeah, I want to know this too. Even serious research railguns have notoriously low efficiencies — something like 2-5% of the electrical energy ends up as projectile kinetic energy. 5% of 1800 joules is about two-thirds the muzzle energy of a .22LR bullet. Enough to be dangerous, but pretty unimpressive considering the size of that thing.

      I also want to know how much velocity actually gets added to the projectile by the rails. Yes, it’s clearly shooting something, but how much of that is just the compressed air injector?

        1. actually since a rail gun uses the projectile itself as the part completing the circuit it should be perfectly timed, every time, which is also why the pneumatic injection is needed to begin with, without it you end up welding the projectile to the rails before it accelerates.

          1. Didn’t realize they used pneumatic injection for rail guns. Thought that conductor on the back side of the projectile just caused enough force to produce propulsion.

    2. The youtube description box claims 250m/s didn’t really pay attention to how they measured it. Whatever they’re shooting also only dented the target. So it’s more bark than bite at this point.

      1. Yup, for reference that’s the same as a pellet gun firing a 16.97gr pellet (average for heavier .22cal pellets) at 820ft/s. ~25.35 foot pounds energy, easily obtainable in precharged guns.

        That railgun is awesome, but you can literally just use that CO2 tank chuck a heavy chunk of lead insanely fast; Decades ago, a couple dudes built a smoothbore CO2 cannon that was able to hurl a 7oz slug with around 1000 foot pounds energy. They called the gun CO2Much.

  1. Oh wow guys! Thanks for posting this to Hackaday! I’m honored! The micro-railgun article you linked was actually one of the things that inspired me to make this. I recreated the micro-railgun design in high school and it worked great. If you guys are interested in more info just hit me up over email.

    1. I think, like me, most people are tired of spelling out the obvious about the us’ unhealthy obsession with lazy people killing machines.

      It’s like arguing about obesity and fastfood chains with a fat diabetic who insists he has anorexia.

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