SpudFiles

Hello,
I am new to Spudfiles and the customs of posting. I also don't fully understand the terms used to describe Pneumatic things.
I find air cannons very interesting and cool and want to know more as well as build one of my own.

I have an idea for an airgun:

It is a coaxial piston valve system made from 3/4 copper pipe with a 1/2 copper pipe barrel. The air release is going to be a blowgun nozzle. I will fill the cannon with air from a bike pump through a schrader valve ( hopefully one that pumps over 200 psi ) i was thinking of making the cannon semi auto with a vast source of compressed air through a regulator. However i want to know how to connect a blowgun nozzle to the copper pipe and regulator ( the fittings ) or how to connect a hose from the regulator to the air supply. My air supply could be a large containment made from pvc ( like a back pack ).

What do you think about my idea?

If you want to use 200 psi, a backpack tank made out of PVC is a bad idea. I suggest just getting the launcher made, then worry about semi auto and all the icing on the cake.

Blowguns have 1/4" NPT threads, so you can use a tube x FIP (female threads) adapter on the copper chamber. From there, a 3/4" x 1/4" bushing (can be brass or galvanized), and then a 1/4" close nipple to a 1/4" tee. You can attach your blowgun to the bottom port of the tee by using another 1/4" close nipple and you can put a bike tire valve (schraeder valve) in the back facing port of the tee.

Thanks for replying.
Could all these fittings be found at a place like "Home Depot"?
Also how would i change the fittings to put a blowgun on to a 1/2 copper pipe? I was thinking of making a 1/2 pipe chamber for the piston valve and 1/4 pipe for the barrel (1/4 i believe is about the size of a 6mm bb)

Just to clarify, can the structure of the airgun be:
1/4 copper connected to an 1/2 to 1/4 adapter pipe (after sanding of the part that prevents the 1/4 from sliding into the 1/2). The adapter to a 1/2 pipe with a piston inside, then connected to a "t" pipe. The bottom port of the "t" will be connected to a corner with a pipe, the pipe is closed with a end cap and schrader valve. The other port of the "t" will connect to a corner pipe that is the fitted with fittings to the blowgun.

Sorry i cant seem to be able to put up my plan onto spudfiles
I hope you understand my description.

I'm not following your description

I see, so my general idea will work.

Can i replace the scrader valve for a source of regulated air to make it semi auto?