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| By bavetta
  5 ratings
This was my first freestanding potato cannon made in '03. Features an automatic pressure regulator and sharpened barrel for easy potato loading. |
This was a lot of fun to play with. I glued together the PVC to put the barrel at a permanent angle of 45 degrees for maximum distance, but it made it hard to transport without putting stress on the connection near the main valve. We could blast potatoes over houses and down the street several blocks. I used 2" PVC pipe (schedule 40) throughout and a 1" RainBird sprinkler valve.
The regulator was a little excessive. It used a mechanical pressure relay to allow for any pressure input, then pressurize the reservoir to exactly the right pressure and shut off the input. This also meant automatic refilling of the reservoir after a shot was made.
I read about sharpening the end of the barrel on the internet and decided to try it out. Turns out it was a fantastic idea and it made loading potatoes a much easier task! When we'd stuff a potato in the rim of the pvc would literally peel the potato down to size.
When filled with water it gave quite a hefty kick-back and an enormous cloud/jet of water was fired. I was in high school at the time, and a high school teacher of mine got word of this and wanted to see it fired. I brought it in, and we fired the cannon filled with water down the hallway! It soaked the whole area. Next, we took it outside and fired several potatoes straight into the air - not a good idea. "Where is it? I can't see it! RUN for cover!" We also tested this cannon with confetti - which was pretty amazing. It instantly made a huge plume of color.
The main problems I found with this design:
- Break point above and below the valve could cause problems
- When loading a potato with a ramrod the seal was so good it was sometimes hard to get the potatoes to stay down. We had to slowly let the air seep around as we pushed the potato down. This could potentially be fixed by opening a valve at the rear of the barrel while loading the potato.
This project cost approx. $30-$40 and was completed in a couple of easy days.
Once again, I must make a remark about safety. PVC pipe is not meant for compressed air. It will fracture instead of leak. This means that you should always wear safety goggles and stay a good distance from the cannon especially when pressurizing. Always proof test the cannon at a higher psi than you will ever use it at to see if it will explode then. They are inherently dangerous, so beware.
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