SpudFiles

This chunk of pipe shall be a coaxial! I just can't decide whether to make the barrel 4" or 2", but it will be 20 feet long because that's how long the 8" is. Unfortunately, it's going to cost more than anything I've ever made. 1 8" end cap is $30, and an 8" x 4" bushing is $45! Plus 20 feet of 2" is $15. I'm just going to use a diaphragm because finding something to make a piston will be really hard and annoying. The pilot will probably be 2 or 3 modded sprinklers or maybe a couple of piston valves. I could probably put a barrel on the pilot valves and still shoot a paintball through my poor tin shed.

you can practically cut down a tree for a piston lol, no seriously, go into a small forest, cut down a tree more than 8" in diameter, and then use a lathe to make a piston, then get like a peice of round metal on each end, a threaded rod, nuts, and a rubber sealing face

you'll want to use a female adapter on the end of it so you can reset the diaphragm if it gets messed up, if you just cap it and it does get out of line, you'll have a very expensive plastic log.

cool. post damage pics too. what will you use as a diaphragm ?
(If you don't use salad's piston idea) how many psi is the pipe rated to. Also, make It a 4 inch barrel,then cut it out a couple inches from the reducer, and put a female threaded coupler on there. that way you can use a 4 inch barrel,and other barrels (use a male fitting and reducers to make other barrels fit. The money spent on this cannon will be well worth it.

If you went with schmanmans idea you would end up with tons of dead space whn you used a different barrel. And schmanman why do you turn every topic into trying to brag about your own cannon?

I edited my first post to get rid of the braggy part

And,I dont try to brag in every post. While I do admit the one in the "ammo Ideas" Is pretty braggy,The one in the "dream cannons" topic is in no way bragging. I simpily am stating that I have my dream cannon. gort did the same thing. a few posts out of 278 is not bragging about my cannon in every post.

I can make you a 4" piston valve that is 4" in and 4" out.

Salad: I couldn't do that because I don't have a lathe.
Spudshot: I'm going to attach it with screws and sealant.
Schmanman: I'm going to use a really big circle of rubber, maybe reinforced with washers in the middle. It's rated to 160 psi, and I will probably do removable barrels with 2 or 3", 4" is 45 bucks for 20 feet.
WOW: So can I, but I don't need it.

wow,It's 45 bucks ? for 10 bucks you can get 10 feet of 4" here.

Try seeing if an empty paint can or bucket would work, they might be big enough. You could also layer a bunch of cardboard and cut it to shape. Just cut a thin ring of the 8" pipe and trace the inside of the circle onto the cardboard, then cut.

A diaphragm will be a whole lot easier, so I'm using that.

can you get 7" end caps? see if a 7" one would work as a piston, or cut some sheet metal/pvc.

do they even make 7" pvc ?

To everyone posting on this topic, I'm using a DIAPHRAGM!

wow,It's 45 bucks ? for 10 bucks you can get 10 feet of 4" here.

Me too. I feel sorry for you guys that have to pay so much for some plastic molded in hollowed out cylinders. The other day a bought a 10' piece of 1.5" for $3 usd.