Potato Gun
August 2003

Introduction

In about May '03 I was considering building a potato gun (also know as a potato canon or spud launcher). I had witnessed one such canon at a family camp called Elim Lodge. Some guys went out on a boat, shot potatoes straight in the air with tremendous force and they'd land in the lake. It looked like lots of fun.

A friend of mine, James informed me that he was going to be building one so I decided that now was a good time to start building.

Note: This is the 'story' of Potato Gun I. I found out what worked and what didn't then I created a much more powerful gun, Potato Gun II and created a how - to - build guide for that gun. If interested, check that out as well. Also, don't forget to check out the many other projects and articles on this site.

After doing some research I came up with a list of the basics:
- Every gun has a wider, shorter section called the combustion chamber and then a longer, skinnier section for the barrel.
- Most guns are powered by WD40 or cheap hairspray.
- Most guns ignite the fuel using a BBQ igniter that creates a spark.

Basic Operation: Stick potato in top, push it down with a pole, unscrew cap, spray 3-6s worth of WD40. Screw back on the cap. AIM and FIRE.

Caution: I contacted my local police department and they informed me that it was fine to use the gun out in the country but did not recommend using it in the city. They are VERY loud and VERY powerful. My gun shoots a potato over 300yds. Noise is also an issue, so please don't use them in a residential neighbourhood.

Igniter

I used a basic BBQ igniter. They can be found for less than $20 at Home Hardware, Canadian Tire or Home Depot. I have bought 3 igniters so far because they keep wearing out on me. I'm currently looking for a battery powered model with no mechanical spark mechanism. If anyone knows where I can get one, please let me know.

I took the cable they provided, used a couple of wire ties to keep it from being too long and glued the ends close together. The ends need to be close together for the spark to travel from one wire to the other. Yes - that is a pen cap I used. It was the closest thing around when I was gluing everything and it's working well.

Gun

The gun body can either be made of PVC or ABS piping. ABS is slightly more expensive, but is less corrosive and stronger so I've heard. I went with ABS because they sold it by the foot at Home Hardware and places around here only sold PVC pipe in 10ft sections. The piping itself is quite cheap (couple dollars / ft) but it's the fittings that raise the price of the project.

This is the gun in it's entirety. It has a barrel lenght of 4 ft and a combustion chambre length of 26". In total, the gun is over 6 feet long and weighs about 9lbs.

Here's a closer look at the combustion chamber. It goes from 4" to 2" using a 4"to3" bushing and then a 3"to2" bushing. Each bushing piece cost about $6. The handle portion is a T-pipe

This is a closer look at the trigger section. I drilled a hole using a spade bit and the size required was coincidentally the same size as an RJ-45 network cable jack so I already had the correct spade for the job. The trigger is secured using hot glue. All of the pipes are held together using pipe glue (about $3.00). Be careful when using the glue because it is corosive. It joins the pipes by corroding a bit of the plastic and "melts" them together. One end of the T-pipe is threaded and I have a threaded cap that matches it. That it where the fuel is sprayed in.

Fuel

My first shot with the gun was in my backyard. Anything in an aerosol can should theoretically work. Take note: Lysol disinfective spray does not. I tried several times to fire it with the spray to no avail. When I was building I was wondering if it would really work and this seemed to confirm my fear that it would not. Next I tried hairspray. I pulled the trigger and heard a thunk as the potato hit the brick of the house. I had some fun with it that night with the hairspray. I shot it straight up in the air and it didn't come down until about 5 seconds later. I fired it at trees and other stationary objects and had lots of fun but I had no idea of the range or power capability. Later that week myself and James headed out to the country by a river to try them out. At first I was dissapointed by the range, but after a few trips we perfected the ammount of spray and the type of fuel to get the best results.

My fuel of choice: WD40
Update: Upon Further Testing with Potato Gun II, Right Guard Deoderant Spray is now my fuel of choice.

It's a fair bit safer than propane, extremely cheap, doesn't leave a sticky residue (although it does leave an oily one) and it's extremely powerful. Using WD40 my gun can launch a standard potato about 300yds. Now that's what I call fun! These guns are extremely powerful, so be careful. Hitting someone with one would surely hospitalize them.

Project Cost

Item:	Cost:
ABS Pipe	15.00
Fittings: joints, caps, bushing, glue	35.00
BBQ Igniter	15.00
Total:	$65.00