SpudFiles

Hi there, I'm new at this whole pneumatic cannon thing, so I've got a quick question.

I made a cannon with a simple ball valve, and it works great. Now I'm trying to move up in the world.

I'm trying to make a semiautomatic gun that you load from the barrel. My current plan is to have the chamber holding compressed air, and then a intermediate chamber that will hold air for a single shot. I'm going to use a sprinkler valve to fire the gun.

Now, how could I automatically fill up the firing chamber? Is there a type of valve that opens when there is a difference in pressure? Any help would be greatly appreciated.

Thank you!

Adjustable pop off valve.

Welcome to Spudfiles.

I made the same type of launcher you're talking about. Use a ball valve in between the two chambers but just barely crack it open so it fills the firing chamber slowly.

Check out the break barrel repeating shotgun in my signature and picture it with a sprinkler valve in place of the main ball valve.

Awesome guys, thanks for the suggestions! This seems like an awesome community. I'll try these out and post my results.

You need a three-way

Using a three way valve as a pilot allows filling of the intermediate chamber when at rest, but blocks off the main chamber when firing.

This is the concept:



The slide valve is basically a three way valve.

A three way valve has three ports, which we will call A, B and C

There are two possible paths, AB (with C blocked off) and AC (with B blocked off)

A is connected to the pilot area of the piston

B is connected to your main tank

C is simply left open to the atmosphere.

At rest, the three way is in position AB. This means your reservoir is filling the launcher chamber.

When the trigger is pulled, the valve switches to position AC. This means the reservoir is blocked off, and is no longer filling the pilot and chamber, while the pilot is exhausted to the atmosphere, which fires the launcher.

Once the trigger is released, the valve goes back to AB, refilles the pilot and chamber and the cycle can be repeated.

You can get cheap pneumatic parts from eBay, check out this thread: http://www.spudfiles.com/forums/semi-au ... 23626.html