Materials needed are:
- a hacksaw
- shaping file or Dremmel
- 1 36 inch length of 2 inch diameter schedule 40 PVC pipe
- 1 3 to 2 inch diameter reducing bushing
- 1 14 inch length 3 inch diameter schedule 40 PVC pipe
- can of PVC primer
- can of PVC cement
- 1 3 inch coupling, one side threaded, one side smooth
- 1/8 inch drill bit
- 5/16 inch drill bit
- a lantern sparker - these are at Walmart in the camping section
- Duct tape
- 1 3 inch diameter threaded PVC end cap
- hairspray in an aerosol can - it must be aerosol not a pump spray
- bag of potatoes
First, cut off a 15" piece of 3" PVC pipe. A hack saw works well and they are inexpensive. The PVC is easy to cut but make sure the cut is as straight as possible.
The cut end is rough with lots of burrs. Since this plastic, the edges are soft and fuzzy, not sharp like with a metal pipe. Spark used his Dremmel and a small grinding wheel to smooth the edges. A file would work as well.
Join a 3" end with screw out plug to one end of the 3" pipe. First, brush on some PVC primer, it is a cool purple color. It is acetone and highly flammable so work outside. It will also permanently stain just about everything, take care!! Next brush on the clear PVC cement.
When you connect the pieces push them together all the way, turning a quarter turn as you join them. The cement will melt and "weld" the pieces to each other. In the picture above the end cap, with screw out plug, has been attached as well as a 3" to 1-1/2" reducer. A five foot section of 1-1/2" PVC pipe is being cemented to the reducer. Let this assembly cure overnight.
A sparker for a gas camping lantern is inserted into the screw out plug. The sparker we used need a 5/16" hole to be drilled through the plug. The sparking assembly is secured to the plug with a nut and washer that come with the sparker.
The inside of the plug shows the flint and wheel that make a spark when the knob on the outside is spun.
The outside of the potato cannon is wrapped with duct tape so no injuries happen if the cannon splinters or comes apart. Spark used the grinding bit on his Dremmel to sharpen the end of the cannon.
Make it sharp enough to cut a plug out of the potato when it pushed onto the barrel.
Push the potato to the bottom of the 1-1/2" barrel with a piece of old broom handle.
Spark's additional decorating.
Spray a two to three second shot of hairspray in the back of the cannon. Use the cheapest hair spray. When the can states that hair spray is explosive they mean it really, really is explosive Quickly screw the plug in.
Spin the brass knob, there will be a loud bang and the potato plug flies about 150 yards. Aim at about a 45 degree angle for best distance. If you do this near a road make sure that no cars are coming. After you are done firing the cannon for the day, shove a wet rag through it and wipe out all the hair spray.