Tater Guns

[JohnF]

I still don't understand why I can't use 150 PSI in PVC that's rated for 220 PSI. Could you or John elaborate on this for me?

Sure. There are two parts to understand. First is energy. Air is compressible and water is not. It might be easier to imagine if we translate compressiblity to stretchability. Air is like a rubber band; by the time a scale attached to one end measures 25lbs you have stored a great deal of energy into it and, if you are like me, you will be hoping it doesn't get loose at you. Water is like a chain, pull a scale to 25lbs big deal, if one end breaks then the chain will fall to the floor.

The other part is a materials problem, specifically how PVC reacts to the sudden release of all of the stored energy inside of it. PVC shatters and shrapnel goes everywhere. Pressure rated ABS will split, no shrapnel, a lot safer. Iron pipe splits. Copper pipe splits. People have been hurt by using PVC for shop air lines. I have read of a plumbers apprentice that was killed when he was pressure testing a PVC run with air. I couldn't find that article again so didn't bring it up so you should take that with a grain of salt.

Face it. A potato gun is a bomb. It wouldn't work if it weren't. It wouldn't be fun if it didn't work.

I do think the .22 thing I mentioned before is something you would enjoy. Part of the fun in materials class is getting to test things to destruction.

For this to super fun we need a BIG feed tank and a bank of compressors feeding it.

[Dan67]

Have you thought about using a 5lb. fire extinguisher bottle for the compression chamber? I have a friend from work and he plays paintball to the extreme and that's what he uses on his compressed air howitzer.

[Rock Doctor]

Will tennis balls fit in 2" pipe?

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I used to make "Tennis Ball Cannons" out of either Soup Cans or old Pop Cans (Can't remember exactly). About 6 of them taped together, top and bottom cut out of all of them except the bottom one. Bottom one just had MOST of the top cut out, and a loading/fireing hole in the bottom side.
Drop a tennis ball in the top, squirt of hairspray in the bottom can, point UP, light hairspray.................Whoever catches the ball wins the round..........Repeat as needed.


Probably get in trouble if I took one of those to the park nowadays


RD