SpudFiles

so i am making a coaxial piston gun, and for some reason, i cant get a good seal on the barrell. i squared off the end of the barrel to the best of my ability, and i have no idea what else could be going wrong! could someone please help me! any tips, or even if you have plans for a piston gun, will help me out immensely. i will post pictures of my piston and design if that will help anyone figure out this problem.


thanks

Pictures would help, along with more details (sealing material, thickness, pipe size, etc.

use a end cap as the piston, and put a rubber coupler on the end of the barrel inside of the valve o use as the sealing surface.

Don't tell him to use an end cap until you know what sizes he's working with. End caps only work well in 4" guns and 1.25" guns with a somewhat good fit. And like donthelegend said, give us details.

i am using a custom made piston out of a peice of 2" pvc with 3" washers screwed onto it, with neoprene on one end of the piston to seal the barrel. i am using a 3" I.D peice of PVC. i will get some pictures up in the morning of my piston, and any other pictures that might help.

pic of piston

here is the part of the barrel that is recessed inside the chamber.

here is the end cap, its a little burnt up, but it still functions.

i was thinking about using a bouncy ball to seal the 1.5" barrel. i saw this on some one elses spud gun, and thought it would work well. also, how big of a spring should i use?

thanks

Look here and see if it helps at all.http://www.spudfiles.com/forums/viewtopic.php?t=3331&
Happy cannoning!!!

any ideas on if the piston i built will work, or should i just start over?

Why wouldn't it work?
And you can use any spring that fits between the cap and the piston really. How big is that ball valve? I'm pretty sure it's 1/2", but it could be 3/4". If it's 1/2" it might not release that much air that fast.

you could still use a rubber coupler on the barrel, because rubber and rubber will seal better than rubber and PVC

EDIT: I like your username, whatthehellamidoing.

i think i have it working. i just added a little bouncy ball thing to the end of the piston, and it seals really nicely. i got a 3lb resistance spring, and it seems to be holding fine. just inside waiting for the glue to set up. going to go pressure it up, and see what it does

is that a mousepad you used for a seal?