DIY coilgun gives clever hobbyists the risk of permanent injury
By Joseph L. Flatley 
posted May 7th 2009 10:44AM
posted May 7th 2009 10:44AM
What's not to love about coilguns? They bring together electromagnetics and DIY-ing for what may be our favorite juvenile pastime: shooting things. The bad boy pictured above was put together by a Mr. Daniel Eindhoven for €100 (that's about $133). A semiautomatic single stage gun that boasts a 14 shot capacity, the weapon's capable of firing a 42 gram projectile at speeds up to 110km/h, with a charge time of 8 seconds when plugged into mains power (or if you're on the go, the internal batteries will light up in about 90 seconds). It also sports a digital voltage display and a laser pointer. Just as we predicted when we saw the Nerf chain gun, the inter-office arms race is definitely on. Be careful! One more pic after the break.
Not in Canada, as long as it is not a replica gun ( Looks like the real thing) or under 500 fps. Airsoft guns have to have clear parts and orange tips.
I'm fairly certain that this guy didn't get the memo that the point of a railgun is to have very very very tiny projectiles go at incredibly fast speeds (not slow speed heavy projectiles)
Not the railgun that the Navy is working on. That's going to fire huge, heavy projectiles very long distances.
That is a coilgun, NOT a railgun. While they both use magnetic forces, the similarity ends there.
This is a coilgun, not a railgun. A coilgun is basically just a linear electric motor.
A coilgun is basically a solenoid.
Like others have said, it's a coilgun, not a railgun. Also, the "point of a railgun" isn't just to shoot tiny things very fast. It's also to shoot big things very fast, or if you had rails long enough you could use it to move a train very fast. It's simply a method of making something move using electricity. The point of it is whatever you design it for.
no, intern. the whole point of that railgun is to demolish your target with kinetic energy instead of explosives. KE = 1/2 m*v^2. so increasing the mass will not increase the energy nearly as much as increasing the velocity. they want to shoot those projectiles as fast as possible.
maveric101 - OH NOES YOU GOT ME WITH AN EQUATION. By your logic, using a capacitor for anything but quick storage and release of energy is misusing them. The underlying principles of matter and energy that allow a railgun to work don't dictate what you need to use it for. People have suggested using them for space launches, and I doubt anyone would bother launching small things into space.
Also, you run into problems at high speeds that you may not be aware of. First of all, there is a terminal velocity for given set of rails and caps at which they can drive any object. If you hit this velocity and you've still got the wattage left over, it makes sense to upgrade to a heavier slug. Second, smaller projectiles are harder to keep on course than larger ones. Ever heard of bullet tumble? Imagine it at eight times the speed of sound. Third, railguns actually kinda suck. You waste a whole lot of energy in the friction between the rails and the slug, usually converting part of both of them to plasma (which means replacing the rails after enough firings). Coilguns are better because the only energy loss in a properly made one is the resistance of the wiring and the internal resistance of the slug.
Video, plz?
Why not make this out of permanent magnets so you never need to plug it in? Just re-load and shoot.
Mmm, big heavy magnet always on?
If I'm correct in describing the theory, a pulse of magnetism is used to draw the projectile into forward motion, then turned off to allow the projectile to continue forward motion away.
A permanent magnet would draw the projectile to it, and keep it there.
for a coilgun to work, you need to turn off the magnetic field as the projectile passes by it.
The whole premise of a coil gun is that a rapidly changing magnetic field induces a huge current in the projectile, which allows it to shoot forward.
Is it just me, or do the capacitors and lightbulb make it look kinda like Clear-Acrylic Steampunk?
It's not just that you need metal, you need conductive metal. While lead could work, it's resistivity is almost 20x that of copper and just under 10x that of aluminum. So I doubt you could get the speeds he's boosting here with a lead bullet.
Wrong. Copper is conductive, but it will not work as a coilgun projectile. You need something that is magnetically active, like iron, steel or cobalt.
@alden
True enough at this scale, though IIRC when you're dealing with weapon or delivery system class mag fields the thing doesn't really care what metal you feed it.
jon-
No, it really matters. It is true that with strong enough magnetic fields you can pull things that aren't ferromagnetic, but you need A LOT of power and you can't pull nonferrmagnetics with nearly the force that you can pull ferromagnetics. There's no point to not using the best material, especially when it's cheaper than the alternatives.
I'd prefer a kimber M1911 – at least until Fauxbamo decides to confiscate them
pew pew!
Wait, so this isn't a weapon that can cause bodily harm which would be totally irresponsibly to teach the public at large how to make?
Can we start featuring DIYs on small homemade explosives to?
Aw, cmon man! Yes, this can (and will) hurt somebody. But really, what doesn't? As the previous posters have pointed out, it'll probably cause a welt. Should we keep this from kids? Yes. The rest of use adults should just put a pair of safety goggles and just let it rip.
Plans Please : )
-Velik
Call me when it gets more dangerous than a slingshot.
On a more serious note, this guy should be careful. shorter than 26" overall length = handgun, handgun + ferrous ammunition = violation of law against armor piercing ammunition.
Depending on the diameter of the rounds it could also be classified as a destructive device, in the same group as grenade launchers.
That means federal weapons charges.
ummm. It shoots at 60 fps. . .
That thing is freaking awesome, but the top part looks like the bastard child of the Titanic and a steam locomotive.
I can't believe no one has said this yet.
"you'll shoot your eye out"
I used to work in the same building as the 9MJ railgun at UT Austin. I saw the tungten projectiles and plates they were penetrating with them. I believe the sabots were made of aluminum and the problem was they would melt and transfer to the bore. From memory they were quoting Mach 6 with a Tungsten projectile about as big as an ink pen.
The capacitors were huge, several of them were used together and about 1.5 stories tall tall. That's what led them to develop flywheel generators for which they are now world leaders in the technology. That's why I was there. Interesting how things work out like that.
If railguns ever are used they will use kinetic energy storage, the trick is it still needs to be hooked up to a good source of power like a nuclear reactor.
http://en.wikipedia.org/wiki/EMALS
I have to say one thing. To all of you who are talking about the legality of this...
FIREARMS LAWS DO NOT APPLY!
This is not a firearm, because it does not use any explosive propellent. This would fall under the same weapons restrictions that you would find for bow and slingshots.
Yeah, it'd be nice if it worked that way. Here's an excerpt from a letter from the BATF:
We have previously examined that certain muzzle loading devices known as "potato guns." These potato guns are constructed from PVC plastic tubing. They use hair spray or a similar aerosol substance for a propellant and have some type of spark igniter. We have determined that these devices, as described, are not firearms provided that they are used solely for launching potatoes for recreational purposes. However, any such devices which are used as weapons or used to launch other forms of projectiles may be firearms and destructive devices as defined.
Bureau of Alcohol, Tobacco, and Firearms
Firearms Technology Branch, Room 6450
650 Massachusetts Avenue NW
Washington, DC 20226
Sincerely yours,
Curtis H. A. Bartlett Acting Chief, Firearms Technology Branch
If you read carefully, you'll notice the deciding factor was not the explosive propellant, but the projectile.
This thing takes the form of a gun and fires metal slugs.
Also, the actual wording of the statute is"explosive or other propellant", not
qualifying what constitutes a propellant.
With firearm's laws, safe is significantly better than sorry.
Let's not forget, this is the same country that's arresting teens for texting nekked pictures of themselves to their friends.
We made one of these in highschool physics class with the capacitiors from prepaid disposable cameras that the local store gave us. It was awesome and totally dangerous and illegal I'm sure... I could only imagine what the PTA would think!
legal? really works? unpractical.
Is that a lightbulb?
yeah, i'd totally use one of these and integrate it into my fog ring blaster
Coil gun?
is this not a rail gun?
and if it isnt it it damn well should be
So can I make a super sized version of this to bolt to my car for rush hour when granny is going 2 miles an hour gawking at the police officer who stopped someone using the HOV lane? Or my personal fav when someone who isn't supost to be being the HOV lane gets the gitters and tries merging when they see a cop ahead. BAM! *Recharge* BAM! *Recharge* BAM!
Why is the laser pointer above the muzzle? It should be below if it's actually going to be used to aim with...
Also, love the light bulb.
+1 for Jon. When the BATF comes a knockin', be ready to grab your ankles and squeal like a pig deliverance style. I'd rather be safe than sorry.
Reminds me of something...
"The designer of the gun had clearly not been instructed to beat about the bush. "Make it evil," he'd been told. "Make it totally clear that this gun has a right end and a wrong end. Make it totally clear to anyone standing at the wrong end that things are going badly for them. If that means sticking all sort of spikes and prongs and blackened bits all over it then so be it. This is not a gun for hanging over the fireplace or sticking in the umbrella stand, it is a gun for going out and making people miserable with."
- Douglas Adams, The Restaurant at the End of the Universe
Wow, that is one cool gun dude!
RT
www.privacy-web.net.tc
Awesome
That is a nice design homemade gadget.
Hmmmm if you put small charges in the projectiles it would be perfect for the coming zombie swine flu >:D Get a head shot and no more zombie brains ^_^
templarian: why not attatch a dynamo to it? then solar energy becomes obsolete in the face of portable, unlimited energy? night or day, rainy or sunny, the dynamo still works on charging the device, provided the user has the time to crank it a few times... but think of the plusses: its silent; PERFECT for sniping, if you can get it to fire at some decent range... *NO* recoil; fire for hours without losing your shot line, so as long as you keep steady, you wont miss...ever.... its compact; Take this baby anywhere, and because it LOOKS so fake, most people will pass it off as a toy pellet gun, or better yet just a noise maker. tust me, these are better weapons than you might think, especially with enough power behind hem...
"I'd solder a piece of wire across the contacts for the batter charger, just to make it simpler. Now take a screwdriver with a plastic or rubberized handle and use the head to tough both of the leads on the capacitor at the same time. http://www.ipodconverter.com If there's a spark, you did it right. If there's not, it just means that the cap wasn't charged."