Low-pressure 3-liter bottle cannon.

[Fnord]

This topic is old, but caulking does work well.
When I used 2liters I would just hold the bottle upside down and create a "plug" of caulking in the top, then just stick a pipe through it and let it dry that way.

[daberno123]

Plumbers Goop also works well. I have used it to glue in shraders in pvc before. Its in a purple tube at most hardware stores

[sniper hero]

use
nut-washer-rubber-bottle-rubber-washer-nut around the schrader
it seals perfect

[ghostman01]

that seriously is the worst place to put that valve, if you were to look at mine its actually right on the bottom and seals by it self and i can put it up to about 120 psi

[Antonio]

I used my piston last time to fire a paintball. I used a 1meter barrel and was working at 7-8bars. It shot 30meters without deviation. Nice gun you made here, as you have epoxy> you should try to make a piston:) I was so impressed by the power of it.

[THUNDERLORD]

@_Fnord that's a cool link on your reply, I live in DC metro area, you could PM me in advance next time there's a cool event (like the jefferson birthday thing). 8)

I had a friend who used to put dry ice in 2 liters with some water at parties.
They went of with a lot of bass/ very dangerous.

So I've always been worried to use them but seems like they are safe at 110-125 psi.

I have been thinking they are so light that someone could make something with several of them for chambers,
seperated by ball valves for multiple shots.

or have like four seperate barrels with a 2or 3 liter on each.

[nibbler125]

i had one of those blow up on me before just use pvc

[n-strike]

Dude, this topic is almost two months old. Don't post in old topics unless you have something useful to say.

[moses]

I hope this is a helpful post.

umm...i would have to disagree with PVC Arsenal 17
soda bottlesare not dangerous if you use them under 110psi
i have been useingthem for all but 1 of my guns, i love the soda bottle chambers they are cheap and they ARE RELIABLE.

Yeah, but it's hard as hell to keep them from leaking when you install schraders... :\

In my experience with water bottle rockets and pneumatic rockets you can safely pressurize a 2l coke bottle to 110psi, the maximum being 120 with a risk of breakage. A 3l bottle should be able to cope with 130-140psi. To attach the Schrader valves to a bottle, I would reccomend that you attach it in this fashion:
I used this on my pneumatic marble gun and it held for all pressures I tested, from 30-100psi. Drill a hole no bigger then the diameter of the thread on the Schrader valve on the base of the bottle, then glue it on with a hot glue gun. now add glue around it and on top of it. Take the cap from your bottle, drill a hole big enough to allow the thread of the valve to pass through. Place over the valve, and glue in place. It should look like the above picture. This is what I'm getting at:

[Antonio]

looks pretty complex..
what I did was drill a smaller hole then the size of the schrader in the bottom of the bottle. (thick bottle> as can go to max 23bar) then buy a plastic tube that is the size of the valve. Push the platic tube from the bottom of the bottle to the top out of its neck. Screw the schrader valve in the top part of the platic tube and pull the plastic tube back down to the bottom of the bottle. Now the valve is on the inside of the bottle and is selfsealing as the more pressure is added the more the vavle seals of.
I dont have a better close up pic, but ill look for one:

[blind909]

@moses, Did you attach that shrader and bottle cap to the bottle with hot glue? if so, very bad choice

[moses]

How so? No problems for me.