Coaxial Pneumatic (Updated/Upgraded)

[Juggernaut12121]

I attempted this a while ago but never finished it because I had no idea what to use as a piston (I first tried using some PVC fitting wrapped in tape but that didn't work at all). After a while I finally got a working piston and I have to say this thing is LOUD, my first shot was at 40 PSI, no projectile or suppressor and it was earsplitting (then again I did it inside). I went outside to test it at 60 PSI with a wax slug against sheet metal and was surprised by the pure power of the piston valve.

Anyway a few specs:
-2" piston
-1/2'' Ball valve pilot valve (I want to upgrade this later)
-.75 caliber barrel, I think it's about 18'' long
-.75 caliber suppressor (want to upgrade this too)
-Minimum operating pressure: about 20 PSI
-Maximum operating pressure: about 150 PSI

That's all I can think of

It's pretty noobish but I love this thing so far. Any recommendations welcomed


UPDATE:
-The pilot is now a 3/4'' sprinkler valve and the pilot for that is a blow gun
-Minimum operating pressure: about 10 PSI

It's louder than originally, but seems a bit better functioning, new pictures at way bottom

[fenrir]

Try keeping the volume between the piston and the pilot low, as this would allow the piston to respond more quickly when piloted.

[Juggernaut12121]

Thanks! I'll be sure to keep that in mind!

[Boomer58cal]

Simple, cheap and functional. I like it.

I'm in the parts gathering/prototyping stage on my first piston valve. I'm building mine inside a 2" sch "80" tee. I'm going to use a sprinkler valve for a pilot, mounted as close to the tee as possible and running a small hose to my trigger(blow gun). I'm not an expert but it's my understanding this pilot setup would be a substantial performance upgrade over your current ball valve mounted several inches from your piston and should improve accuracy. Just food for thought.

I'd shoot the heck out of something with it. Good job.

[Juggernaut12121]

Thanks! I used the ball valve and the weird 'c' shaped section since it was what I had laying around. Once I get money I'll upgrade to a sprinkler valve and probably mount the blow gun on the handle in the middle of it. That and the piston's pretty inefficient so I'll be redoing that next

[Boomer58cal]

That's what I'm talking about! Good job. I bet that things pretty nice to shoot now.
You would think the piston would react faster. Was there any noticeable power gain?

[Juggernaut12121]

I'm not sure yet. I threw it together last night and was only able to dry fire it once or twice, although the piston striking back is more audible and the recoil went from zero to hardly noticeable. It is a whole nother world to hold and aim though, the trigger is up front where is ought to be and the butt end is fatter than the 1/2" pipe producing a more stable shouldering