piston material

[subterranean]

ok im building a an over/under pneumatic cannon and i am having trouble finding some simple plans for a piston valve(not coaxil). Im also wondering what materials i will need for this type of valve(the piston specifically) I dont have a lathe so i need to know if theres any other way to make a good valve. The chamber will be 3" and the barrel 1.5". i want to make the valve 2" because i dont have a place to get 3" pressure fittings.

[Kobl]

Ask Gort, he'll know what to do! Jay kidz.

You could use 2" pvc rod as piston in 2" pipe, or you could make a hot glue piston with a mold. Oh yeah, don't forge the sealing face, some nice thick neoprene or usually anything else will do.

-Butt

[subterranean]

where do i get neoprene rubber from? and how exactly do i bore out the t fitting for the piston to pass through ?

[crazyfreak0075]

Hey if you're going to make a gun make a piston out of pvc rod or something like that. I asked a question similar to this and someone told me that Gort said the 2" pvc rod on mcmaster.com fits very close to the 2" pipe im not entirely sure though.

Materials you will need are o-rings, piston valve material (pvc rod, ect.), rubber or neoprene to make a good seal with the barrel.

EDIT: The gif i tried to upload wont work so here is the link the the t-fitting animation. http://www.spudfiles.com/forums/viewtopic.php?t=6765&

[subterranean]

On the left side of the T-fitting, is that the barrel inserted using a shaved bushing?

[crazyfreak0075]

Yeah im pretty sure it is. And you mean chamber instead of barrel right?

[singularity]

you can make a piston really easy by finding an end cap that fits in loosely and putting a couple of layers of duck tape. ive only tested it in a 3 inch coaxial but so far its worked awesome. o yeah i put like an end plug in open end of the end cap and ca glued a layer of rubber to it so it would make a good seal

heres a pic of my piston

<img src="http://i78.photobucket.com/albums/j85/i ... CN2216.jpg">

[judgment_arms]

Well here’s my two cents ($0.02u.s.):

One, I call that type of valve a “tee valve”, because it’s a valve made out of a tee, anybody with a head on there shoulders would know what you’re talking about… at least I would.

Two, although I’ve haven’t made a tee valve yet I have made a coaxial and I find that hot glue works great, it’s simple and easy to use, just be careful hot glue is, well, hot…
Plus since it made of hot glue you can take a soldering iron and melt a little glue to glue your sealing face on.

But that just my two cents…

[subterranean]

thnx very much guys for the help! I hate to be greedy but does any one have a set of plans or instuctions for making the hot glue piston.
thnx again.

[judgment_arms]

You ain’t greedy, just lazy. All you’re doing is casting a piston. I’ll tell you this much: you need to melt the glue, and you need to have a mold with the same ID as the pipe that the piston need to fit in. i.e. if you need a three inch piston you need a mold with a ID of three inches.

[c19o]

theres a video on making a whole valve in a tee that uses a hot glue piston on www.bcvids.com

[hi]

I molded my piston out of hot glue sticks and bolted a cut up inter tube on it. it works great and seals every time.

[subterranean]

c19o, the website is restricting me from accessing that video. do you have a different link?

[c19o]

theres a link somewhere on this site. I forgot where though, jsut look around.