Introduction: Make a Poweful Railgun!

Picture of Make a Poweful Railgun!


Step 1: Obtain Parts

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Step 2: Assemble the Enclosure

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Step 3: Make the Bank

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Step 4: Make the Charger

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Step 5:

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InfinityHex (author)2015-11-25

Hello I'm doing a project for school and I was wondering if there's any videos that show it getting build for that I could get a better idea of the layout and I was wondering what safety precautions would be sensible to do before getting started.

Rileyd5 (author)InfinityHex2017-02-02

it depends on your skill, i know this is probably way past time but i think this may help. this project is obviously done at your own risk. but if you want to build one you just have to get a few things straightened out, you need the voltage and amperage to power this which is probably a project of its own if you don't have access to the power supply beefy enough to handle it. second you need the proper frame and rails. the rails are ideally tempered aluminum or copper. (i've tried using copper and it tends to start warping and getting melted after 5 or so shots and have to be adjusted after that.) and if you have access to 3D printer(s) it would be ideal to print parts of the frame to avoid arcing and potential for shocking yourself or bystanders if they are near you or the device. Third you need the correct projectile and capacitors. 600 volts is quite a bit over kill and 300 is also a little much as it sometimes tends to arc through the firing mechanism and possible the rails depending of the size of the gap between them (when i built mine i used two servos from rc cars, one to put the aluminum bolt into firing position and a second beefier one to actually fling it fast enough into the rails then have the rails take over from there.) and then there's the bolt I've tried steel .308 bullets copper and then i ended up milling them using the shop in my school out of aluminum about 1/4 of an inch in diameter at the fattest but still "bulet" shaped. And to all the people saying it's impossible for a high schooler to build these... well i built mine when i was thirteen with little to no help from others except my uncle loaning me $75 bucks to buy three of the caps. if you are really determined use as much scrap and salvaged parts as you can it keeps cost way down and the parts you have to buy at a minimum, i will attach pictures of the rifle when i dig it out of my families storage shed sometime this month or so.

CadeConnelly (author)Rileyd52017-05-22

So I got ahold of sixteen 400v 150uf capacitors, I plan to use a "hot rail" design like the one here. Should I go ahead and purchase a couple more farads worth of capacitors? Also, I have designed a circuit to charge from 120v ac using a transformer (I will rewrap an old microwave transformer with 12:40 turns), and four diodes to rectify the current. My problem is that I am not sure what gauge wire I need to have for the transformer and what the diodes need to be rated for. I know that I at least need them to be rated for 400v, but I am unsure of what amperages this will put through the different components of my circuit. I have heard of putting a limiting resistor on the charging circuit to reduce the amperage, but I am not sure what to use if I do. I only know enough right now to do something stupid, so pointers from anyone who better understands circuits would be much appreciated.

InfinityHex (author)InfinityHex2015-11-25

I bet this a dumb question but couldn't you use a wall socket?

_atlas (author)InfinityHex2017-02-06


Hey, I am a highs school student and u made a rail gun as an engineering project, I used a wall socket but was then connected to a step-up transformer that I got out of a microwave

InfinityHex (author)InfinityHex2015-11-25

Please respond as soon as possible!!!!

Based MbekeO (author)InfinityHex2016-04-28

No. Do NOT do this project. Find something simpler, cheaper, and safer. In order to build this you have to know what you are doing. Which means you have to know a lot about electricity, safety, and engineering. It is expensive and would take a while for a high schooler to build. It is also extremely dangerous. It is several thousand volts which can easily kill you. This is more a project for someone in college who understands this stuff. And no, you cannot use a wall socket. House circuits are normally around 140 volts, which is not nearly enough to power this.

Robochicken (author)Based MbekeO2016-12-26

It's not the voltage that will kill you it's the amps

IsaiahC14 (author)Based MbekeO2016-10-04

its obvious you dont know much about electricity, as its the amperage of a current thats lethal

BluzD (author)InfinityHex2016-04-13

What grade are you in cause if you under 9th grade level d ok not do this at school it can harn children really bad and even fatal

Spencer10000 (author)2017-01-28

is it possible to make it holdable, for example, a plastic box, if so, how thick should the plastic be?

Rileyd5 (author)Spencer100002017-02-02

yes, but your going to have to put in some work for it to fit into something portable

neil137 (author)2015-08-15

sorry im not sure how to ask questions on this site but it seems to be the place with people in the know.

i have several thousand dollars and a few months on my hands. i want a railgun. i dont mean the weak ones everyone else has. i want one that

rivals a rifle in speed and could do some seriious damage. could anyone point me to what parts to order from online?

or any tips to wiring and assembly? i have friends with cnc equipment and plenty of spare metal so it's not an issue, i just need some basic instructions

on how to get started and what speeds would be possible. if i have to incoporate a backpack too that's fine. i just want to put solid proof out there

that it's possible with todays tech. thank you.

lapince (author)neil1372016-03-19

Man I hope you guys don't want to do stupid things with it, I know in the US there is more freedom for this kind of things but in France if you build one and use it even in your property law enforcement won't be happy, this thing is awesome but I would be too scared of it blowing in my face lol

BenderSanchez (author)2015-06-09

The link in step 4 is spoilt just for your information.

Hobos_Bazooka (author)2013-03-23

Is the capacitors in series or parallel
Thanks would really like to know

KyleV1 (author)Hobos_Bazooka2015-05-31

Parallel. In parallel the capacitence just adds up, in series that go in to 1/(1/capacitence)

GreenD (author)2010-01-10

Cool, but it seems like almost all of your energy is going into creating plasma, and not actually accelerating your projectile - it may be better to have a lower voltage, no?

I plan to make a smaller hand held one using the small 350 volt, 330 uF capacitors. I like this idea though. Have you experimentedwith lower voltages?

WillR10 (author)GreenD2015-05-31

Also, lower voltage = higher ohms = power loss to heat, so that's swapped logic. (That's why longer electric runs use higher voltages)
I agree with the plasma though; you can see energy being dispersed in directions other than forward. Hard to say how much is friction, and how much is electrical heat.. could try with a more conductive and/or more heat resistant material.. and I would think a longer, thinner projectile would accelerate more easily. (Maybe even with a point at the nose)

rp181 (author)GreenD2010-01-10

400 volts is already low, you want as high voltage as possible. Higher voltage, higher peak current

lucek (author)rp1812010-07-03

he dose have a point you are wasting a bit of energy on that flash that's not getting converted to kinetic energy.

nuclear12321 (author)2013-08-07

One thing I am curious of is why not use batteries to power a railgun? Yes, they do not have as high voltages as capacitors, but that makes them easy to charge. A good lithium polymer battery can have an internal resistance of 5 millifarads, so the short circuit current of a 10 cell battery (7400 amps) does not seem to be a problem. Their energy density is high enough that I can get out 30 shots before having to recharge. It seems like a perfect match? Now all I need is somebody to shoot out my dreams and tell me why it won't work :)

Additionally, I have a question about railguns: Does the voltage you input to them relate to the power of them in any way? The only things I can find tell me to maximize the amperage. While a high voltage does ensure a high amperage, does it matter at all otherwise?

WillR10 (author)nuclear123212015-05-31

I'm not an expert, but from what I've read, amps effect magnetism, not volts. So, lower volts would hit higher amps with less electricity, however, the resistance goes up with lower volts, and you'll burn up (everything) quicker. So, I'd imagine it's a balance of heat capacity vs available power.
I'd think a battery bank would work (assuming you've taken into account the factors involved with batteries and heavy draw), however, you could not use the same design without a concern of your capacitors blowing up.
Did you ever make it? more youtube vids would rock!

the simple answer is discharge rate. most caps of this type will discharge all there energy in one go you need that in a railgun

xarlock667 (author)2013-11-17

I will point out two things, and understand they are NOT criticism, just to help you make a badass project badasser.
1) F=BILD/M^2
What the hell is that? The force equation for a rail gun. Everyone seems to miss 2 crucial points. First, that after the F and before the M every variable is a multiple. That helps you amp up your power. Second is that /m^2 at the end. That means that your total power is divided by the weight of your projectile. SQUARED. Ouch! Go with a smaller/lighter projectile, and you multiply your power.

2) Friction is KILLING your projectiles! (Ok, some may be flashing to plasma, but I bet most are being ground to powder) Get some dielectric grease from one of the many parts stores and grease up a BB. Then put something big and heavy in front of your gun. Then make sure you film it and send me a link!

TimothyH4 (author)xarlock6672015-04-28

Hey Xarlock, check your units there, I don't think you did your math right. F= Kg*M/S^2 or mass*length/time^2 or ML/S^2. If B is mag strength in tesla and we call A=amps then you are proposing ((M/AS^2)*A*L*L)/M^2 = (L^2)/(MS^2), which is not a unit of force. Typically when talking about force due to magnetic fields it is the distance term that is squared, could that be your issue? Now I have no experience with railguns, only started lookin into making my own recently, but from an engineers perspective I would suggest double checking your calculations.

Caligula35 (author)2015-03-05

I am novice in this sort of thing and am not sure if i should go with one low volt 20farad cap or one low farad 8000 volt cap or wether both would melt the 1.5 meter long aluminium rails.

Caligula35 (author)Caligula352015-03-05

I could use more than one if it would make it more powerful but what would be the maximum amount i could use?

tbriscoe12 (author)2015-01-23

Hope this isn't too dumb of a question. Although copper rails would be nice because of its conductive properties the heat generation could be an issue? I know it is more conductive with electricity but also more conductive with heat than steel or aluminium is.

紀衡賴 (author)2015-01-08

I'm having problems with charging my 400V capacitor. How do I setup something to charge the thing with an AC power source?

Anargopunk (author)2014-11-14


I am student at a school for electrical engeneering and i talked to a teacher about the topic and he says that, if you use complemantary coils around the rail part, you don't need a higher voltage, just a super high Current, because Amps are actualy a size for magnetic field, and volts for electric fields, so in my project i'm using a 1.5V 2A adaptor for charging my 200Farad 2.2V ultra-caps because the volt's don't matter.

General Eggs (author)2011-06-02

do you need to use resistors for any part of this? I'm making a small scale one for a science project.

evilmadcow (author)General Eggs2012-09-04

use a coilgun!
much cheaper

Tobor 2.0 (author)evilmadcow2013-04-22

idk, coilguns are significantly harder to work with and make (at least with all my experiences)

evilmadcow (author)Tobor 2.02014-06-29

well, it does depend. power matching is significantly harder, but he is doing it for a science project, meaning there is a high likelihood it will got to a science fair. if it kills someone, that would be bad.

very bad.

Skwurlito (author)2014-04-17

This is a coilgun, not a railgun. a coilgun accelerates a pherosmetal projectile with electromagnetism. it is also the least efficient way of accelerating a projectile as only roughly 11% of the energy exerted is used in propulsion as compared to a bullet where nearly all the energy exerted is used.
a railgun is a similar concept where electricity is the projectile. A close match is a taser.

MainAvel (author)Skwurlito2014-06-19

A coilgun uses freaking coils. Do you see coils here? Do you?

tazerboy (author)2011-06-08

Also, GreenD having a 350volt 330uf capacitor is very weak,( around 20joules). Especially, when you are trying to make a railgun, because railguns are not that
efficient in the first place.I would recommended at least 100 joules( three 450v 470uf), to get some effective muzzle energy.

drozzle (author)tazerboy2011-07-12

Railguns are much more efficient than traditional firearms. A well made medium size railgun can have around 30kj of force, that is almost as much as the worlds largest rifle.

tazerboy (author)drozzle2011-07-12

yes, but you are forgetting that i am talking about a railgun powered by 20 joules,
and when you said 30kj I believe that is how much the energy the capacitor bank produces, and not the railgun. Due the fact that the largest rifle produces around the thousand joule range or a tiny bit higher. not nearly as powerful as 30,000 joules. However i could be wrong, can anybody attest or object?

matt73hl33tn355 (author)tazerboy2012-06-20

Actually, yes. I can object to that. The rifle is not what makes the energy, it is the amount of gunpowder in a round of ammunition. The .50 BMG, or Browning Machine Gun round is used in the Barrett M82 sniper rifle, and has a muzzle energy of (depending on the weight) anywhere from 18,000-20,100 Joules. No, that isn't 30kJ, but it is well over 1,000J. Most handguns/small-caliber rifles will put you around the 1000-Joule range, though.

To drozzle: to have a capacitor bank charged at 30kJ would be extremely expensive, and would take up a LOT of space. look at the pictures of this one. The capacitor bank is about 18 inches long, and you would need five of those to get near 30kJ. However, if it is "well made," as you said, the induced back-emf would be very small, and the energy of your capacitor bank could be very nearly the energy you actually get on the projectile.

tazerboy (author)matt73hl33tn3552012-06-21

BTW induced back emf only appears on coilguns not railguns, because in coilguns if the pulse timing is too long for the coil to shoot through the coil, then the magnetic field instead of letting the projectile gain speed, it will pull it back. Thats back-emf. The current railguns don't have coils so this problem doesn't exist, the best way to achieve an efficient shot of a railgun is to full discharge the cap right when the projectile exit's the barrel or rail in this case. ALSO for people who want to make good coilgun/railgun, i recommend you use high voltage low capacitance capacitors like High Voltage Oil Capacitors, I have one its 5.5KVDC and 32uF. they have very low ESR, which means they discharge very fast, and with very high peak power. NOTE, the less capacitance you have the faster you discharge.

nuclear12321 (author)tazerboy2013-08-07

I would like to input that while a higher voltage will ensure a faster discharge, that does not mean that you should cut back on the capacitance of your capacitors. Ideally you want the charge to last until the projectile leaves the rails, as they get more powerful the longer the rails are, and I doubt a 32 microfarad capacitor can supply power for that long. If a capacitor has an internal resistance of one ohm, the voltage of the capacitor will be identical to the output of it, and regardless of the voltage, the number of farads is the number of seconds that the capacitor can supply a current for. So assuming the one ohm internal resistance, tazerboy's capacitor can supply fifty thousand five hundred amps, but only for thirty two MILLIONTHS of a second. A quick calculation suggests that is in the range of 500 joules, so I believe one can do better with a 400 volt capacitor that has 6500 microfarads of capacitance (also about 500 joules). This, in turn, will provide a mere 400 amps, but for a full 6.5 milliseconds. That, I believe, will do better.

matt73hl33tn355 (author)tazerboy2012-06-22

Oh, hey yeah. You're right. Sorry, I must have gotten the two ideas mixed up in my head somehow. Thanks for straightening me out! Also, why is higher voltage the better way to go? I get that in the equation for capacitance, voltage is squared and so is more important, but doesn't your power supply have to be very high voltage as well to charge the caps?

tazerboy (author)matt73hl33tn3552012-06-27

Well in order to have cap that packs a punch you would either need very high capacitance or very high voltage. The good thing about high voltages caps are low capacitance, while still capable of delivering the same amount of high energy. Low capacitance mean very fast discharge rate, much faster than those 450v caps, and the result is very high peak current, more brute force in a smaller package. It's is especially good in coil guns because since 5.5kv 32uf cap has such a small capacitance the coil won't have problems with back emf. Yes your power supply also needs to be at the same(or a bit less) as the voltage in the caps, i hope to use a ZVS driver with a self wound transformer and a recifier. however its rather difficult to find the recifier that will go that high, I might need to put them isn series. Good luck!

tazerboy (author)matt73hl33tn3552012-06-21

Although i am wrong about the muzzle energy of guns, the point here is to prove that 20j railgun won't do much at all.

matt73hl33tn355 (author)tazerboy2012-06-22

Haha, yeah. Your projectile would be... moving at a very slow speed. I mean, it would be the safest railgun ever! But it wouldn't be very impressive.

tazerboy (author)matt73hl33tn3552012-06-27

I don't think it would even move lol

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