Here are some general instructions on how you can make a potato cannon. This cannon will fire potato slugs at around 150 miles per hour up to hundreds of feet.
I take no responsibility for any injuries or property damage that occur with this toy. A potato cannon is capable of causing serious injury either with an impact of the potato or with an explosion of the cannon itself.
First you must gather materials:
· 1/4" thick 1 1/2" diameter PVC barrel (around 5 feet plus or minus)
· 1/4" thick 4" diameter PVC chamber (around 1 1/2 feet plus or minus)
· 1/4" thick barrel to chamber reducer
· saddle tee (rides on top of chamber with no penetration)
· 1 1/2" grip (around 1 foot long plus or minus)
· end cap for grip
· gas grill sparker
· heavy gauge wire
· wire nuts
· 2 1/4 x 20 x 3" bolts and six nuts
· 1/4" thick end cap for 4" chamber
· 1/4" thick screw cleanout for chamber end cap
· PVC cement
· spray solvent, hair spray, or ether, etc. for propellant
Now assemble the cannon:
· cut and cement together all the PVC parts as shown.
· note: the grip assembly should only require cement between the saddle and the grip tube, not to the chamber or the grip end cap.
· drill holes for the gas grill sparker, sparker bolts, and sparker wire escapes.
· wire the sparker to the sparker bolts through the grip and sparker wire escape holes.
· note: keep the wires away from each other as they could short out before the spark bolts and not cause a spark in the chamber.
· note: keep the wires away from where the operator's arms and legs will be. if the wires come into contact with skin, they will give off a shock, even through insulation.
· file the inside of the end of the barrel to cut and reduce the potato slugs when loading.
· wait sufficient time for the cement to dry.
To fire the cannon:
· Remove the breach cleanout to allow air to escape from the chamber when you ram the potato in the muzzle.
· Ram the potato into the muzzle using a blunt ram rod (a broomstic with a spool nailed to the end will work).
· note: the potato should end up at least a couple inches shy of the chamber.
· spray propellant into the breach.
· note well: you don't need very much at all (psht).
· screw the breach cleanout back on.
· make sure all friendly personnel are clear of the line of fire.
· depress the firing sparker button.
· lather, rinse, repeat.
I started work on another potato cannon today. This one has some improvements over the first one. No wiring will be exposed because the bolts are encapsulated within a box. This will prevent accidental shocks for righties and lefties. The bolts serve a dual purpose---they also keep the box in place. Because the two bolts are inline instead of on opposite sides of the chamber, I needed to solder a copper wire to one of the bolts to bridge the gap. This is possible because I used brass bolts instead of steel. Brass should stand up to moisture better too.
More updates as construction and testing progress.