A cheap air compressor...

[Ragnarok]

I've done a similar thing in dreams where I find a load of cash, start thinking of a launcher I could make with it, then wake up and realise that dream money doesn't help in the real world.

Quite disappointing, but many of my launcher designs are actually part designed in my sleep - always jot ideas down ASAP when you wake up, you'll forget them quickly.

[psycix]

Would getting addicted to spudding and unable to stop thinking about new designs be dangerous or a harmful addiction?

[DYI]

It would certainly be a harmful addiction, I don't know about really dangerous though. Most of the people here are the type of people that can get really immersed in a hobby, but you have to make sure it doesn't take over your life. I would be worried if I started dreaming about new designs, but I never remember my dreams anyway.

[wangpushups]

I was thinking about making a bolt action co-axil, have you guys seen plans for this or thought of it?

[f.c]

i also think about making new guns in my sleep lol. and this explains all you need to know about a pneumatic.

The price of a pnuematic depends on the type of valve you use to fire the cannon. A piston valve is the cheapest as you can make one for next to nothing, and they perform very well.
QEV valves are a bit more pricey, but are built by profesional manufacturers and therefore are very durable and will always work as long as you have it set up well.
Sprinkler valves are cheap ($10+) but need modding in order to make them actuate pnuematicaly.
Burst-disc is the most efficient as it has no choke-effect on the barrel/ammo, but can be a pain to make if you don't have a union-valve at hand.

Filling a pnuematic is easily achievable with a suitable bike pump. However, if the chaamber is huge, then a compressor will be needed.

The basic route to a pnuematic is a fill-valve, chamber, "trigger" valve and a barrel. Most important of all is to make it air-tight.

I have no ecperience with the useofPVC as in the UK copper pipe is more readly avaliable. but I'm sure many American folk can help you with that.

[DYI]

It must be nice to have pressure rated PVC readily available. It doesn't even exist here. ]

You can always look to the SWAT gun as inspiration for a great pneumatic cannon design. Even cut down to half size, the design is compact, and powerful, while looking relatively good. I would add breech loading though.

A breechloading coaxial piston valved pneumatic is possible, but it would be a real b*tch to seal, and offers no real benefits over the much simpler breech loading over under barrel sealing piston valve configuration.

[wangpushups]

I just got out of sears and i passed up a 3 gallon air compressor for $80, im really gonna kick myself in the ass for this cause i couldve saved myself $50...original price was like $130...damn it!

[BigGrib]

It just boggles my mind sometimes on how far apart we all really are and the fact that some places pnuematic parts good pnuematic parts that is are harder to come by. There are a few really cool specialty parts that I have the fortunate ability to be able to get fairly cheap one of which is aluminum cam locks. Not something you see everyday. So if anyone is interested in some of the parts that I am able to get my hands on gimme a pm and I let you know and if i can get anything for anyone just let me know.