DaGrimRaper,(
)
Here at Spudfiles we provide the information and the help, we don't provide the teaching. There is no point teaching calculus to someone who doesn't understand it, they have to have a general knowledge of it.
What you need to do now is go to the Spudwiki, located top right of the page, and spend some time going through the Pneumatic Cannon Discussion and Showcase sections. It would also do you good if you look at the stickies in the How-To section on 'How-To: Mod a sprinkler valve'.
Once we know that you have some clue to how everything works, we can then help you with your design and construction.
For starters, if you live in America, a 1" sprinkler valve will cost you between $10-$15. The real purpose of a sprinkler valve is for irrigation involving pressurized water, so you should find them in the Irrigation/Plumbing section of a Home Depot.
As you can now tell, a sprinkler valve is a valve, a valve regulates or completely stops a fluid from going through a passage. In a sprinkler valve this is done by the
'diaphragm'. When you fill your chamber up with air, the air leaks through an
'equalization' hole in the diaphragm and into the
'pilot volume'. This air pressure in the pilot volume then pushes the rubber diaphragm down and seals the hole to the chamber.
So now the pressure can build up in the chamber while the diaphragm is sealed against the chamber port in the valve. A sprinkler valve usually uses a
'solenoid' to empty the pilot volume, but us Spudders find that solenoids are too slow and restrict flow, meaning the valve opens slower. You also need 3x9v batteries to operate them.
So instead we use a blow gun, this does the same job except it's pneumatic and not electric like a solenoid. When you mod the valve so the blow gun is above the pilot volume area, the valve in the blow gun holds back the pressure in the pilot volume keeping the valve sealed.
Once you press the trigger on the blow gun, it opens the valve in the blow gun, letting the air pressure in the pilot volume out, this creates an unequal force on the diaphragm, which now has pressure from the chamber pushing it up, but no pressure holding it down, so the diaphragm opens very, very quickly, letting the air out into the barrel port, and firing your projectile.
And to install the valve you just need threaded fittings which can be found at home depot.
Hope you understand everything, if not just ask.
You should also read this:
http://www.spudfiles.com/spud_wiki/inde ... _Rated_PVC
