Piston concept question...

[THUNDERLORD]

I was day dreaming about piston designs and how to make a good one and wondered,

The front of the piston is made out of rubber to seal against the barrel opening which is metal.
So being engineer minded I inverted that and thought what if the barrel opening had a rubber washer or rubber tube attached and the piston was all aluminum or plastic to be lighter

Does anyone know about that, just never seen one like that. And I am wondering why not since in theory it would open faster?

[Lentamentalisk]

Yes that would work just fine. Generally piston weights aren't cared about to that extent, but it could be very useful in a piston hybrid where the piston hitting the back can sometimes kill your gun.

[THUNDERLORD]

Thanks for the reply Lentamentalisk,

It's not only the weight that would be improved but friction and that the rubber piece at the barrel opening could be constructed more "heavy- duty"
It just seems like a more sound design (if it works).

Maybe I could test a small scale version and use an aluminum gutter nail head (for the piston) with the spring around the body of it
and a pneumatic air hose tube cut of for the sealing face.
Mounted stationary to the barrel and one at the exhuast port.
Thanks for the advice.

[Gippeto]

I do believe that JSR has used that on at least one project.

Found it;

http://www.spudfiles.com/forums/pneumat ... t7858.html

[jackssmirkingrevenge]

You mean like this?

[THUNDERLORD]

Wow, I feel stupid now,
I really didn't take the time to understand the pen gun or ever see the awesome video with schematic of your other gun.

Perhaps it was subliminal as I swear I day dreamed it up today.

One day very soon(maybe tommorrow) I am going to take the time to read every single post of yours.(I'll give you credit for whatever new ideas I learn).

Now you saved me from hours of testing a concept on something small scale I wouldn't really want. Thanks JSR and Gippeto.

Can't figure out why you never see that concept used more?
Like always, your designs are genius JSR. Spudfiles is Cool!!!

[Blitz]

I kind of applied that concept to some of my break-barrel breeches. Works well if held solid.

[THUNDERLORD]

Well with these responses, I am sure I could make it work.

Thanks Blitz, I am trying to check out your creations but my security set-up is blocking the picture.

I'll have to look some more for one I can see.

[biged]

Like this?


I call it a linear coaxial piston.

(Picture before it was all welded up.)

It's for a tennis ball bazooka.

(Work in progress.)

///ed///

[psycix]

Thats quite a nice piston setup biged!
Optimal flow if the porting is big enough and the space around the piston is too.

[jrrdw]

Sounds kinda problem matic, sealing materail attched to the barrel could probly get sucked into the barrel more easly then having it on the piston.

[rcman50166]

Well since we're on the topic of piston valves, how do you guys think clear silicon window caulk would work as a seal? The stuff seems like a good fit. It's flexible, rubbery, cheap and comes in large amounts. Has anyone ever used silicon caulk for a seal before?

[pat123]

I have tried the silicon. it falls apart to easily for. It is really cheap so give it a try.

[SpudFarm]

Larda has a coaxial with a o-ring groove on the seat and a piston just out of plastic woth no sealing face.

[DYI]

Well yes, but larda's piston and sealing face are probably milled to such high tolerances that a conventional sealing face is unneccesary. Unfortunately, we don't all have that capability.

Butyl rubber makes an excellent sealing face material, but I don't know how well it would do used in an application like this.