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.
WANT
want very much!
OH MY GOD
QUAKE
III
RAILGUN
I MUST HAVE THAT....
I WILL DO ANYTHING.
ANYTHINGGGGGGGGGGGGGGGG
actually, coilgun
similar name, very different things.
I know the difference between coilguns and railguns...this looks like the railgun from Quake.
Anyway...
This is the first DIY in a while...
it looks like it's shooting tampons..
LET THE WAR BEGIN!!!!!!!!!!
Well, We ARE the resistance. Might as well make something that looks high tech to ward off the Terminators.
you resistance can get the hell away from the coilguns. everyone knows the last thing you want in your coils is resistance.
Haha, yeah andres. AP Physics for the win.
Anyways more coilguns, electrothermal guns, pneumatics, combustions, hybrids, strafers, ect on spudfiles. com.
instructions pls
If you don't know how to build it, you probably shouldn't.
Part of the fun of DIY is when things go terribly wrong. I'd like to see some instructions, too.
OK, where to start? Coilguns work because when you apply a current to an insulated coil, you end up with a magnetic field. If you push more current through at a higher pressure (those in the know call this "voltage") you get a stronger magnetic field. So, what can push a whole lot of direct current (DC for those of you playing along at home) through some wire really fast? Well, batteries can so the whole "a lot of current" thing, but they can't do it particularly fast. This is why we use capacitors. They're like batteries that can release all of their stored energy all at once. So, all you really have to do is wrap a bunch of wire around a barrel of some sort, attach either end of the coil to a capacitor and a switch and let it fly.
The absolute easiest way you could make a coilgun RIGHT NOW is to grab a disposable camera with a flash. Pull the flash circuit out (don't shock yourself now) and identify the charging switch (it's probably two metal contacts side by side), the battery terminals (durrrrr) and the capacitor (It'll be the biggest thing on there. It might have some writing like 250uf/320v on it. In any case, it will be a cylinder). 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. If there's a spark, you did it right. If there's not, it just means that the cap wasn't charged. ALWAYS BE CAREFUL WITH CAPACITORS. They hold their charges for a long time and it can hurt like a bitch/kill you if the capacitor is big enough. Now make your coil. I used a drinking straw that was just big enough to fit a copper-clad steel BB with a tiny bit of room. For those who don't know how to wind a coil, read this:http://www.angelfire.com/electronic/funwithtubes/Coils-1.html
OK, so now you have a coil on your barrel, yes? Stick something in the straw (I used a bent piece of aluminum) so that when you slide your projectile in it will stop just after/just inside the coil. Now connect one end of the coil to one of the leads on the capacitor and hook the other end of the coil into the other lead on the cap through a switch/button. This will be your trigger. Load the sucker up, charge the capacitor by putting the batter back in it's place and flip the switch. If it doesn't work it means you messed up. Keep in mind that if your projectile doesn't react to a magnet it's not going to work.
Just google it, they're not hard to make. Of course, making one like this would be a little harder.
Camera flashes use a flyback circuit which both stores the energy in an inductor (not a capacitor) and uses the inductor itself to generate the very high voltages needed to fire a xenon strobe.
This device would be well served to use a flyback also, it probably does.
Alden
While I like your instructions, I'm disappointed that you suggested closing the circuit with a screwdriver to test for current.
Capacitors that have a stored charge can EXPLODE if you do this. Its never a good idea to short circuit caps.
As for building a railgun or a coilgun, I did an experiment for my science class building a graphite firing railgun using 2Farad Capacitors and car batteries.
I was able to blow a hole through a brick.
Look on youtube and you might find the video if its still up.
keyword (railgun, class , experiment)
Quantumphysics -
There's no way that the cap in a disposable flash is going to have enough juice to pop just from being shorted with no load once or twice. I suppose I could have said "grab a spare computer fan and short the cap through it" or something like that, but for a relatively low power, soon-to-be-trash project like this it's OK to be rough on your passives.
Also, why a railgun? You waste so much energy turning the projectile and rails into plasma.
I want to make one of these so bad...but I'm so afraid that I'll hurt myself with it.
Man, hopefully that's not the splody kind of capacitor. I've had one(much smaller) blow up in my hand, not fun.
You're supposed to throw the exploding capacitors like hand grenades.
It's... beautiful ;____;
If this is what a DYI can do for €100 (about $133) what the hell is the Military working on in their labs?
S C A N N E R S ! "Enemies: Dare to cross us, else we will think (really really) hard - and your head shall explode." Who needs physical weapons any more?
You don't even want to know
Theirs can take out a satellite in orbit. Plus the idea of needing a power supplied gun and ammunition probably isn't the best idea in a battle.
"Wait guys let me just attach this solar panel and in 2 to 4 hours you will be toast, unless it gets cloudy or in the off chance I'm shot first".
The military put a prototype rail gun on a C130 gunship over ten years ago. It fires small projectiles at hypervelocities and was intended to knock out small point targets without a lot of collateral damage. The problem with the system is the huge power supply needed and the recharge time for the capacitor banks which limits the rate of fire.
Oh, I dunno, something that goes fast enough to hurt.
This throws a very light object at about the same speed you can throw a baseball.
The military is probably more excited about regular old pistols that throw projectiles about 1100km/h.
Yeah, see, this thing fires at about 100fps. A good handgun fires at 1200fps. A rifle, much more. This is a neat toy, but entirely useless as a weapon.
100.2474 feet / second
68.3507 MPH
I think my toy bb gun shoots a bb around 250 FPS... well, at most...
And theirs runs on liquid Naquadah.
You guys realise that the projectiles this thing fires are 42 grams and not 42 grains (a respectable size for a rifle bullet), right? 15x the mass there. Unfortunately, the relationship between mass and velocity in this thing isn't linear, or you'd be able to fire a 42 grain bullet from it at 1500fps.
Someone with better knowledge of ballistics and/or electromagnetism would be able to construct a better model of the device's potential, of course.
I already feel the thousand knives poised to strike me cold for this, but there is a certain potential here for steampunkery, if not 50's sci-fi...uh...unkery on the design side.
OOOH! Or some 30's era slipstreaming? Yeah man.
Either way it's incredible and I covet this in my heart.
I totally agree....make it kind of "fallout" looking.
Uh...need metal bullets for this, right?
Ouch.
Uhh, lead is a metal, so is the copper jacket.
but they aren't ferrous...
The point was not the type of metal, etc, but that it's metal.
>>>> ...Just as we predicted when we saw the Nerf chain gun, the inter-office
>>>> arms race is definitely on.
Ouch.
Not a big ouch...
It only has a muzzle velocity of about 100 feet per second (110 km/h =100.25 f/s) and a decently large round. It also lacks riffling (the spiral groves in a gun barrel) so the range/accuracey will be reduced.
For comparison:
A $10 airsoft gun will fire a 6mm metal ball at about 200 ft/s. A cheep BB gun will shoot a .118 BB at about 300 ft/s. You local cop's 9mm round will leave his gun at about 1000 ft/s. Now that will hurt!
However, as with any projectile, a hit in the right place can cause serious injury or death.
I should have looked farther down prior to posting. Have they added a way to edit these comments yet?
The type of metal doesn't really matter, as long as it's a conductor. The coils induce a charge in the metal.
With that laser pointer it should be pretty easy to bullseye a womp rat.
A Womp Rat?
Why they're only about two meters wide!
Thats 43g at 100 feet per second = 19.8 joules of energy or 14.6 foot pounds,
With a range of about 13m or 45 feet
Source= http://www.arniesairsoft.co.uk/?filnavn=/articles/fps_limits/fps_calc.htm
Thats a shit load of energy there....
Considering 1 joule is the max allowed for airsoft in the UK because 1 joule won't puncture the skin this this could be deadly....
You would probably need a firearms license for this.
Raptor
This is probably more "nasty welt" territory than anything else. Keep in mind a 9mm handgun fires a projectile at over 1100 feet per second, with muzzle energy in the 350-400 ft/lb range. The projectiles seem to be much heavier here but cross-sectional density and the resulting ballistics coefficient, which is an important aspect in both internal and external ballistics, is probably much lower with the coilgun projectile due to the difference in lead and copper vs a less dense ferrous alloy. 14.6 ft/lbs is more what a very nice .22 pellet rifle could do.
Fuck. When did engadget turn into CSI?
It's WAY too early in the morning for this kind of talk!
Keep in mind this goes about the same speed as an ordinary adult can throw a baseball and weighs about 1/3rd as much. Every day one MLB player gets hits by a ball going faster than this and it does hurt, but it is far from needing a firearms license.
I have a compressed air cannon that will shoot a Nerf football over 100 yards. It delivers a lot more energy than this, and it is not classified as a firearm (at least in my state).
@why not the LS2LS7?
but your forgetting that sense the baseball is much larger it has more surface area, plus its much softer than metal. so it doesn't put all of that energy into the same space as that "bullet".
The only way to be sure is to shoot some people with one.