Really, with a pnematic, the ratio is a matter of choise. Once the chamber:barrel is about 2:1 , larger chambers barly help. How are you going to have to fill this most of the time? That's the main question. If you are going to fill this with a 12v thing, I would go with a smaller chamber. On the ot...

6 mm is... close to what I have? Um... 22mm/ inch, 22/16=1.5.
Meaning that I have 4.5 mm neoprean? (3/16")
Does any one else have trouble with 4.5mm?

Yeah, cellular core means that the pipe wall is mostly "hard foam". It has a thin layer of solid PVC on the outside, but don't let that fool you. You could try poking the wall of you pipe (from the end) with a nail or something. If it dents it at all, anywhere, don't use it!

Ok, so I'v made my first cannon, a 2" barreled, 4" chamber diaphram (ball vaulve acctuated) pnematic cannon. (yes, I'm pretty ambitious) "Great", you say, but what's the problem? Ok, here it is: http://img.photobucket.com/albums/v611/car2/vaulveD.jpg As you can see, we have a washer pair lending rig...

Yeah, and you where using cellular core pipe, wern't you?
If you make a pnematic out of cellular core, it's just as dangerous...

Better? Definatly a pnematic! If I remember, peak pressures in a combustion are around 30-60 PSI, where a pnematic is often operated at pressures in the 100+ range. A good combustion with a good propelent is quite simmilar to a pnematic. Combustions can be simpler then pnematics, and their fuel is a...

Yes, anything's better than a ball vaulve!
2X? I'v heard 'up to 4X'... anyway, it's a BIG differance. A sprinkler vaulve works by letting the air out from behind it. From the box, it opens a tiny hole with a solinoid - when you mod it, you replace the tiny vaulve with a much larger vaulve.

Well, Joel's groves are non-symetrical - triangle shaped, with one side coming up at an angel, and the other coming up verticaly - but they used to be retangular. (from looking at the picture) they seem to be about 1/5-1/4 of an inch wide, and maybe 1/3 of that deep. Joel uses 6 groves, but any numb...

And I don't think anyone has the money to buy a supha vaulve just to disect it...

Well, it won't really shread the potatoe, but the potatoe that sticks into the groves will break off. Ok, here's an attempt to explain why the potatoe bits in the narrow-deep cuts will break off: Think of these peices of potatoe sticking into the groves as sticks stuck in a vice. You push down on th...

This is going to be a multi-pass operation. I mean, it will take dozens or even hundreds of trips down the barrel to get nice groves. As such, don't even attempt it by hand. Get the twisted guide rod, and push it over it repeatedly. I would recement cutting 3 or more groves at once, to keep the bori...

I think that there's sopposed to be a arrow on the valve... is it pointing towards your barrel. If not, that's probably why it's not working.

I'd like to point out that the pneumatics can generate speeds way too high to safly use for paintball. You can put non-frozen balls through those 55 gallon plastic barrels, and that's not with a insanly sized gun. A combustion could be done, but then again, those things can shoot very fast too. My a...

If it came down to "toggle switch secector/multiple triggers/variable pressure switch" I'd chose 3 bottons in a vertical arangment. However, I'v come up with a possible option: have the firing of each barrel deselect that barrel, and select the next, using pressure activated piston-switches. This sy...

I'm planing on making a multi-barreled combustion. (3 barrels) To ignite it, I will have 3 capacitors. I will charge them, then discharge one per barrel. A bit like having three cannons wired to one trigger. However, I don't want them all to shoot at once, I want them to shoot sequentially - prefera...