How to Build a Potato Gun
October 2003
Page 1: Design and Construction
Page 2: Comparissons and Field Tests
Introduction
This guide will show you exactly how to build a potato gun. These spud launchers are quite powerful and I take absolutely no responsibility for what you do with this information. In most places of the US it is legal to own these canons, and in my area of Canada they are legal as well - but check with your local authorities before building to make sure.
Step 1: Design and Planning
I really like the design of Spud Launcher I. I think it looks really cool, so I more or less duplicated the design for Spud Launcher II. This time around instead of blindly building I did a bit of research on the ideal combustion chambre volume to barrel volume ratio. Information on this is hard to come by but one source said 1.5:1 was ideal. I measured Spud Launcher I and it had a ratio of 2.1:1 and it was quite powerful. If I followed a 1.5:1 ratio the gun would totally loose the cool "canon" appearance so I decided to go with a ratio of 1.8 : 1. This means that the barrel is a bit longer and the chambre is a bit shorter than Potato Gun I.
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I planned to use 4" ABS for the chambre and 2" ABS for the barrel. |
Step 2: Shopping
If you've got a basic gun design in mind, you can keep this in mind when you go to the hardware store and see what's avaliable. Here's a list of parts I bought for my gun:
- 13" of 4" ABS |
- 3" to 2" Bushing - 4" Threaded Adapter - 3" Threaded Adapter - 4x4x3" ABS T-Pipe (the handle) |
- 4" Threaded Plug - 3" Threaded Plug - Electric BBQ Starter - Push Button |
I went to both Home Hardware and Home Depot, compared prices then bought what I needed. Most things were cheaper at Home Depot and they had better selection.
When doing your measurements, don't forget to include the length of the T-Pipe and anything else you include in your design. If I bought 21" of 4" ABS - my combustion chambre length would be closer to 3 ft.
Step 3: Getting Ready
Here's all the parts I bought laid out - basically how they'll be put together.
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Here's a list of tools you may need:
- Drill - Glue Gun - Tape Measure -File
Step 4: Assembly
Warning: the ABS cement is corrusive. It won't burn your skin, but it's not a good idea to spill it on your clothes. If you want to try something fun, the cement does eat through styra-foam.
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Use newspaper or something to cover where you're working. You don't want to get the glue on something important. |
 Take the glue and apply on the inside surface (less noticeable). Make sure you use lots of glue and get it ALL the way around. |
 Push the 2 pieces together, they should fit together easily. |
The two pieces are joined, easy as pie. The glue only takes a few minutes to set, so try not to have to pull 2 pieces apart if you make a mistake. |
Construct the Handle and Chambre Portion of the gun using the same technique.
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The glue and pipe are very easy to work with. The 3" threaded adapter is attached to the bottom of the T-Pipe "handle". The 4" threaded adapter is attached to the back of the T-Pipe. This will be unscrewed to put in the propellant. |
 Potato Gun I (Top) & Potato Gun II (Bottom) |
 Chambre Partially Assembled |
 Chambre Fully Assembled |
If you have all the parts, to assemble the gun takes about 20 mins (not counting ignition installation). Once you have the chambre assembled you should install the Ignition System. It's much easier to work with a 2ft gun than a 6ft gun when installing the ignition system.
Ignition System
In Spud Launcher I, I used a standard push-button BBQ Igniter. (About $15cdn). I've replaced it 3 times - they wear out fairly quickely and do not gaurantee a spark every time. This time around I went the more expensive but RELIABLE route of using an electric BBQ igniter (about $25). These work with a battery and when the button is pushed, about 5 sparks / second are produced. Very effective.
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The inside of the electric BBQ igniter. I replaced the standard push button it came with a push button switch with longer wires. That way I don't need to reach INTO the gun to push the ignition switch =) |
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The push button switch I'm planning to use is the black one in the bottom left of the picture. It's also the same switches I'm using in my Mame Project. |
Drilling and Filing
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Another reason I wanted to go with the electric BBQ igniter is that I could use a smaller switch rather than the large push button I was using before. This also minimizes the slight risk of the switch blowing out - literally. A small hole is drilled. Easy as Pie. As Mr. Burns my Calculus teacher would say: "Done like dinner". |
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Assembling the gun took about 20 minutes - max. But getting this tiny switch to fit in that hole took more than an hour. I had to file and file and file some more to remove enough ABS to fit it in. Quite fustrating and time consuming. It took so long because of the ackward angle it was at. I got it in the end though. This was the most time consuming part of the project - aside from writing this article. |
Fitting the Ignition System
The purpose of having the bottom of the handle be removable is because I wanted to place the BBQ igniter inside it and also be able to unscrew it to replace the battery when necessary. Also, by putting a threaded cap into the bottom - it creates a much sturdier fit than just gluing the cap in like I did in Potato Gun I. This became problematic after a fair bit of use.
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The trigger is now installed . Looks great in my opinion. The ignition cable is glued inside the gun as shown (far left). |
 A little glue is all it takes. |
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2 of the wires go to the trigger switch. The other 2 go to the ignition cable. It is the same one used in Potato Gun I. The igniter came with the parts required to make another cable, but it's much easier to use one that's already made. |
The 3" with the electric igniter is screwed in and the ignition system is installed. When you hit the switch you hear a "click-click-click..." of the spark going. Very nifty.
Fitting the Barrel
This is just another glue-n-push and the gun is complete.
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Page 1: Design and Construction
Page 2: Comparissons and Field Tests
Comments
I like it but i want to know ,to make a gun in a sample way
Posted by muzafir00 on 2012-02-1 @ 07:29
ow they really hurt when they hit you
Posted by dan on 2011-12-14 @ 16:53
Great site but your calculations for determining the C:B ratio is incorrect. Volume=Pi * RADIUS sq * length. In your calc you used the diameter instead. And from the research I've done the ideal C:B ratio is 0.6-0.8..Other than that very informative website!
Posted by Qwerty789-789 on 2011-04-15 @ 06:42
A word to the wise: don't use ABS cement to fill the hole for the button/wires if you're using an electric ignition system. It is flammable and also appears to be conductive, which can result in current going places you don't want it to, like your fingers.
Posted by on 2011-03-26 @ 06:56
Thanks for the info.Just what i was looking for.
Posted by chandula on 2011-02-1 @ 05:44
while am assembling the setup we can't bring "ABS cement" here (In India ABS cement is not available in market) so that i used fevicol instead ,,,now i am feeling some jerking in the setup while triggering the circuit
Posted by Alex on 2010-11-18 @ 21:11
is their anyway to spend less money and get the same results?
Posted by spancA on 2010-10-5 @ 13:55
thanks for your info. Just built mine off your specs, now I'm having to wait for the glue to dry. How long do you spray your combustibles for? Guess I will figure it out soon. Thanks dude!
Posted by scott on 2010-09-24 @ 18:41
Have you tried a pneumatic air potato gun? It is similar but with the exception that the charge is entirely air and not combustion... the lower barrel of 4 inch abs has within it a can as a pneumatic piston. a small piece of rubber in the bottom of the can for a seal. rubber bands for a seal around the side of the can. and a sprinkler valve [low voltage selonoid type]...at the base is a ball valve and an air fitting and a guage to tell what the pressure is... fill the chamber with air presssure/ release the sprinkler valve to dump the air behind the can inside./the air ahead of the can shifts suddenly and launches the projectile. severe damage to a sheet of osb wood paneling can result. James T.
Posted by jetusa on 2010-09-22 @ 00:18
I agree potato guns are awesome! why not check out these proffessional potato gun plans for only $1
http://tinyurl.com/28qd9e6
Posted by spudMan on 2010-09-11 @ 18:33
A word to the wise: don't use ABS cement to fill the hole for the button/wires if you're using an electric ignition system. It is flammable and also appears to be conductive, which can result in current going places you don't want it to, like your fingers.
Posted by Jordan on 2010-08-28 @ 13:26
i found that the best lighter is a stick bbq lighter that you can get cheap. and u also don't need the t peice on top you can just have a bigger chamber with the crew on cap because u only drill a hole in the side and stick in the lighter and glue it into place.
Posted by brad on 2010-08-16 @ 16:54
it is all right
Posted by mic on 2010-05-26 @ 04:44
Best thing I found for igniters is a old style Coleman lantern igniter. Not nearly a fancy as a push button but its cheap, very reliable, and simple.
Thought I suppose you could get creative and hook up a belt or gear system to tie hook it into a little motor... Would eat quite a bit of flint but look nifty.
Posted by bert on 2010-04-28 @ 05:47
it SUCKS
Posted by bob on 2010-04-15 @ 16:27
can i make this out of PVC
Posted by Alex on 2010-04-3 @ 07:33
you know i love to shoot my potato gun and all but yall are gay
Posted by bryan on 2010-03-31 @ 07:03
I'm doing this for a science fair project. Should I do a live/in front of my teacher or make a video for him?
Posted by Guy with a question on 2010-03-5 @ 12:44
How much does it cost to buy all of the items necessary?
Posted by Spartan 117 on 2010-03-5 @ 12:27
I have made several potato guns and found that the most reliable ignitor is one of those long butane BBQ grill lighter with the end epoxied into the cap of the gun. I alos epoxy a handle onto the cap so it can easily be removed and make sure to sharped\serate the end of the cannon so that the potato is cut to size as it is pressed into the end of the barrel.
Posted by MyName on 2010-02-23 @ 16:41
how hard was this thing to make
Posted by ittybity on 2009-11-28 @ 20:38
i made my first tater gun when i was nine i have made a few different thing to i made a pee shooter and one that shoots tenis balls and one that shoots arrows my next one is going to try to make one that shoots a watermelon if anyone has one send me the pictures i wanna see it cowboy5_11_90@yahoo.com
Posted by big country on 2009-09-17 @ 21:13
I built a mini spud gun out of the P-trap kit you can pick up @ walmart for 5$, and a red push button ignition also sold @ walmart for 8 bucks, glue the parts with some PVC glue and custom cut a cap for the end out of a frisbee... You get a fun lil contraption for under 20$, only lasted through 30lbs of taters before the cops came and I had to crawl under the sink acting like a plumber... I think the 3 empty cans of aqua net on the back deck gave it away... But atleast we put a couple holes in an old oil drum before they arrived to spoil the fun... Cheap lil way to stir up some trouble. took me bout 30 min to build and was fun as hell with the right amount of jack daniels added... Try it out!
Posted by chris on 2009-08-27 @ 20:15
you can buy a much better potato gun at www.spudgundepot.com my friend told me about this website. I bought a extremely powerful potato gun for about 30 bucks
Posted by killspud on 2009-08-1 @ 09:22
Specializing in pneumatic and combustion-based launchers including a variety of types, styles, sizes, and feature levels for potato vectoring.
i heard some cheap domain name for potato gun website. But i don't know what was it. When i will find it then surly share with you.
Posted by angela67 on 2009-07-9 @ 03:28
Hey in from australia there ilegal here,and for my one wich is custon like yours I have a 1ft chamber 4in wide and for the barrel its 3in and 4ft long so including everything its 5 1/2 feet long,I use start ya bastard for the gas as its used to start old cars another thing I have found that works realy well is the conola oil spray not hair spray or other things like that ,
I also use frozen oranges if I can find any big enough to fit in,
Using the start ya bastard I get a frozen orange to go about 4km (1000ms in a km),
And with the conola oil spray I get about 3 1/2 kms.
Using the oil spray is good in a way because it lubricates the whole thing making the orange slide through very easily.
Keep up the good work mate and loved the idea of the electric igniter.
Posted by pete on 2009-07-7 @ 06:34
This things sucks, make a pneumatic one.
Posted by Mean joe on 2009-02-27 @ 05:01
I shot at a cop car and ran away they still busted my ass tho. so my advice is try to hit the pig next time.
Posted by rondo on 2009-01-25 @ 18:48
I bought all my stuff from Home Depot when building this thing.
Posted by PwnStick on 2008-12-26 @ 16:52
If you have to ask...
Posted by Another User on 2008-09-20 @ 00:00
how hard is it to make and any ideas where to get all the stuff in england?
Posted by jake on 2008-09-19 @ 14:39