SpudFiles

This is my second pneumatic canon. Before I ask for advice I would like to set a little background on the cannon and its use.

I built this cannon specifically for airsoft. I use it to clear rooms at the local CQB (close quarter combat) field. It uses 120 psi from a bike pump. The ammo is 100-200 airsoft bbs. I first rip a cotton ball in half and shove it pack it down the barrel. Then comes as many bbs as I can fit. Then it is finished off with the other half of the cotton ball so that the bbs don't fall out when I'm lugging it around on the sling I put on it. The only problem is that I can only use it one time per round because i can not lug the bike pump and take the time to reload during a match.



My idea is to take away the 1" extra tank space that I put to add power by means of more air behind the projectile. This would make it possible for me to make more of the smaller cannons instead of trying to reload the bigger one. I was wondering if anyone knew the figures for an air cannons cubic inches as related to power. Do you think that taking the extra space away would significantly reduce the power? Has anyone designed a PVC "canister" that could be pressurized and used to fill up a cannon for one shot? Any ideas, suggestions, or constructive criticism would be greatly appreciated.

You could carry pressurized 1 litter bottles with ball valves and screw them in to repressurize.

Where do i get the proper tread to thread onto the 1 liter bottles though?

Co2... Go and buy a 20 oz. bottle and a regulator and your problem is solved. Soda bottles won't work, trust me. Co2 is a better investment if you are going to use the cannon a lot.

I'm sorry that I am unfamiliar with some things due to the fact that I am a cannon noob, but what is a regulator?

Ok I found out about regulators, but where do I buy one?

A regulator is a device that brings the pressure down. C02 is usually around 800psi which is unsafe for a pvc gun. With an adjustable regulator you bring the pressure down to 120psi or whatever you like. Be aware that C02 will make the pvc brittle because of the cold temperature.

Edit: I type too slow you found it while I was typing.

Well.. How brittle? I don't want this thing blowing up on me or anything. And where do i get a regulator?

Well! the best way if you want repetitive shots for cost effectiveness to get a disconnect setup (Someone help me out with the names here). Also make burst disk cartridges (look it up, it's on the spudfiles) so you can reload a cartridge each time.

With the disconnect set up you need a male and female disconnect. The male disconnect adaptor should already be on the gun, where as the female disconnect are on each air tank. This way each shot you'll have to disconnect the empty air tank and add in a new one.

The cartridges should also make it easier to reload. You'll have to do 2 things at once, but I guess this is one of the easiest ways to go. Also, maybe you should upgrade a ball valve (BV) into a piston valve (PV) you'll get better performance, but I guess you want to keep it simple?

Hope that helped you.

I looked up the piston valve and it seems: A. Too Complex B. Too Expensive (my whole cannon cost 10 bucks to make) C. Too Bulky (Unless there are really small ones out there)

Reeyah wrote:I looked up the piston valve and it seems: A. Too Complex B. Too Expensive (my whole cannon cost 10 bucks to make) C. Too Bulky (Unless there are really small ones out there)

But!!! Compensating for expense-wise would be...

A. Better performance, since the valve opens quicker a BV.
B. There ARE designs that aren't bulky, if you are looking for an co-axial (inline piston, if I'm not correct, correct me).
C. Firing a Piston Valve seems more ergo rather than twisting your hand to fire, you can use your finger.

But 10 dollars to make is pretty good. I guess it's your choice.

alright mate, I will give you what I think you should do,

Make an even bigger tank, something big, maybe even backpack sized, then have a (pressure rated!) hose run from that to a ball valve (we will call it A), then from the ball valve through your smaller chamber, then to the next ball valve (we will call it ball valve B) , then barrel.

You fill the big chamber, then open then close ball valve A to fill up the small chamber, then open b to fire, close b, then open and close ball valve A ETC ETC...

I thought about something like that but I need portable. I will be running through dark rooms getting shot at from odd angles and such while carrying and using an airsoft aeg. A backpack would weigh me down. I think that a co2 tank with a pressure regulator is starting to sound like what I need and I might make a breach loading of some sort and figure out a cartridge setup of some sort.

sputnick wrote:alright mate, I will give you what I think you should do,

Make an even bigger tank, something big, maybe even backpack sized, then have a (pressure rated!) hose run from that to a ball valve (we will call it A), then from the ball valve through your smaller chamber, then to the next ball valve (we will call it ball valve B) , then barrel.

You fill the big chamber, then open then close ball valve A to fill up the small chamber, then open b to fire, close b, then open and close ball valve A ETC ETC...

I like the backpack. I would add an air compressor regulator to it. Many fields have a max FPS requirement. With a regulator, you can get several shots at full power before the pressure drops off. If using a CO2 or Nitrogen tank, the backpack is much smaller. The downside is the $$$$ for the setup

Where are the cheapest regulators for co2 for 120 psi?