Piston Valve Improvement

[Hubb]

The other day, I was watching the Discovery Channel. The show "How It's Made" was on. I wasn't really paying attention at first, but then they started talking about how a flute is made (modern flute with all the buttons and shiny stuff).

The show got to the point where they were talking about sealing the holes when the buttons are pressed. It said that a piece of felt is placed first, then a piece of rubber.

I got to thinking. Assuming the felt was used to cushion the rubber against the edges to be sealed, thus creating a better seal, I figured why couldn't this be done with a piston.

Maybe it's been thought of, maybe not. I haven't seen it done yet. It may even solve some problems with persons having leaks around the piston seal area.

I've included a diagram to help explain it.

[spanerman]

Yeah that should help with uneven sealing faces ect.....

[VH_man]

YES!!!! i did this with my first piston because it wouldnt seal....... and it did.

i got the idea from my mom's rubber stamps, but same difference.

this is better for high-pressure cannons. in high-pressure cannons a thicker, stiffer rubber must be used, but once you use that, if you dont have everything perfect it wont seal. if you put felt behind it, you can use uber-hard rubber and still have a seal........

thank you for reminding me of this. will be used in the future..........

[Hubb]

I was also wondering if it would be better to have the felt fixed so that it will not move, then put a light piece of rubber (maybe one layer of inner tube) to seal the piston. That way, it will sort of squish against the sealing surface.

[noob of noobs]

That's a good idea, but how would you secure the felt and rubber to the piston's body? I know that if you bolt things, the rubber ussualy flares out, which would cancel out the felts effect.

[Hubb]

That's a good idea, but how would you secure the felt and rubber to the piston's body? I know that if you bolt things, the rubber ussualy flares out, which would cancel out the felts effect.

With glue?

[HaiThar]

Good idea...If I ever decide to do a piston, I will try this

[noob of noobs]

I suppose glue would work, but I've heard that piston sealing faces are notorious for being sucked into barrels due to suction. I'm not sure I'd trust glue to hold somthing that important on, since if it did rip off, the gun'd fire spontaneouly.

[Lentamentalisk]

use some flexible rubber cement. that stuff sticks like crazy, yet still allows for some stretching, as is completely necessary if it is going to be squishing around an uneven surface.
thats my input at least

[Hubb]

Lentamentalisk has the right idea. It should stick quite nicely and when it dries, it is soft, which will further aid the sealing.

[psycix]

Yeah its a nice idea:
A 100% hard pistonsurface can only seal an 100% square cut pipe.
A more flexible pistonsurface can "bend" in such a way that uneveness is sealed too.
Now with this pelt you create a very flexible piston surface making up for better sealing.

its nice

[noob of noobs]

Does the rubber cement act as an actual seal? That sounds pretty good... Where can you get that stuff? But are you sure it won't rip off? I have some bad experiences with adheisives...

[Hubb]

The rubber cement should be used to hold the felt to the piston. I've never used it on a piston valve so I don't know if it will rip off or not. Super glue, on the other hand, should hold it, but it may leak through the felt and cause it to stiffen up, which would then defeat the whole purpose of this mod.

If necessary, I guess one could put more than one screw in the rubber / felt to hold it better.