All current cannons are primarily constructed of schedule 40 PVC pipe. PVC pipe has various pressure rating thresholds depending on pipe size, but nominally have a working pressure rating about 230 psi for 1.5" pipe. Air pressure chambers for the compressed air cannons use this pvc pipe. It is suggested that air pressure is limited to only 100 psi in the compressed air cannons. This leaves plenty of room for error and safety
The compressed air can be pumped into the air chamber through the schrader valve (tire valve). I have found that 100psi is the optimum pressure to have with a 2" PVC barrel and air chamber of 3 foot lengths. The best ratio to have for the barrel/chamber length is 1 to 1. This will provide adequate air to propel the contents in the barrel.
All PVC parts must be glued together using PVC glue. All threaded pipe connectors must use Teflon plumbers tape (and lots of it) The hardest part in the construction is making an airtight pressure chamber. If the chamber is not air tight, then the pressure will slowly leak out and leave you with a "dud" when you need it most - on the paintball field! The best procedure is to put it all together and pressurize it, then check for leaks with a soap and water solution (a spray bottle works best).
Many different lengths and sizes of PVC can be used. I have experimented with several and have had mixed results. Generally, the longer the barrel, the more accurate the gun. You can make this according to the expected use of your gun. If you plan to use it as a defensive weapon (i.e.: defending the flag) then a larger model may be in order. For offensive maneuvers, shorter, less bulky cannons are needed.
CO2 Cannons:
CO2 cannons are somewhat different in construction than the compressed air models. CO2 is much higher pressure than the compressed air. The PVC air tanks can not be used on CO2 cannons due to the danger of exploding the tank. Therefore, a steel pipe fitting system is utilized to contain the propellant for the cannon. The barrel and valve is the same for the CO2 cannons as they are for the compressed air cannons.
CO2 is either supplied using a 12 gram quick change adapter or an ASA adapter that will allow the attachment of a constant air bottle or remote setup. The CO2 cannons are a favorite for paintball game use. The compressed cannons are more suited for recreational use.
Packing Wads:
A packing wad is a device placed in the barrel of a cannon before the ammo/load is put in. The purpose of the packing wad is to create a tight seal between the load and the force of air pushing the load out of the barrel. If a packing wad is not used, much air will escape the barrel without pushing out the contents first. This also depends on the load. If you fire bunch of paintballs out of your cannon with out a packing wad, the small gaps between the paintballs will leave a path for gas to escape through, lowering your range and cannons effectiveness. Packing wads can be made from many heap items laying around your house. The most effective is the plastic cup packing wads, but they are a pain to make and carry, and you will only get a few uses out of them before they blow apart. Other ideas for packing wads are:
 | paper towels |
| plastic bags |
| foam plugs |
| Styrofoam |
Each type of packing wad has its advantages. You may want to try them all to see which ones you like best.
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