SpudFiles

This weekend im making a simple pneumatic golfball cannon. What i want to know is what the minimum volume/length my pressure chamber needs to be to get a good result out of the cannon.

The barrel is 1m 40cm (4Foot 7In) long (i can allways shorten it)
and for the pressure chamber i plan to use 50mm pipe which is rated to about 200psi. i will only be using it 100-150.

Also i was wondering where is can get a cheap sprinkler valve in australia. i tried the add on the site for <13 dollar sprinkler valves but they don't ship to australia, and if i get it off the internet i don't think it would get here in time.

Thanks for your help!

bunnings sell sprinkler valve. i would go for a 1.2:1 C/B ratio. and dont shorten your barrel, longer is better (try not jsr)

Definitely don't shorten it. Good performance can be had with high pressure and a moderate size chamber. Here is my Marshmallow cannon. I have a selection of screw on barrels for various ammo sizes. The golfball barrel is the one attached to the launcher in this photo.

DO NOT cut the barrel, leave it as long as possible. Why don't you try making a 2" piston valve? It is very simple and probably the best valve to use for a golf ball gun (Don't wanna hear it, Tech )

I might make a piston valve. but how would i make the piston?

For a 2" piston, the easiest way would be a 1.25" coupling with plugs on each end. Then, bolt on yourr rubber sealing face and wrap it with duct tape until it fits, or if your feel like it, add o-rings for a tighter fit. Have a look at Superna, my first 2" piston cannon for a more detailed look at a 2" piston valve, also the Hubb Library has a link on how to make a 2" piston with a built in check valve, like mine. The check valve prevents backflow into the pilot area from the chamber, so the cannon loses less air and opens quicker.

A simple how to for the entire gun including 2 pistons
http://www.instructables.com/id/Golfbal ... That-Shoo/

A great piston material for a 2 inch piston valve is 2 inch UHMW Plastic Rod from McMaster... The ID for 2 inch SCH 40 PVC is 2.047, so a 2 inch rod is a very nice fit with one wrap of electrical tape.

Site: http://www.mcmaster.com/#

Part Number: 8701K49