Simple Semi Automatic Concept

[sagthegreat]

high pressure as in?
for me high pressure is 300psi
for jsr it could be 1000psi
so what exactly is high pressure

[Gun Freak]

300 psi would work but you'd need a bigger chamber and quicker valve. We're gradually making our way to hammer valve grounds...

[jackssmirkingrevenge]

from another thread:

here's some inspirational projects:

http://www.spudfiles.com/forums/viewtop ... tml#225468

http://www.spudfiles.com/forums/6mm-mag ... 21684.html

some useful advice given to an idiot:

http://www.spudfiles.com/forums/valve-help-t22198.html

[wyz2285]

We're gradually making our way to hammer valve grounds...

Or use it to pilot a QEV for more power...
Jack, he is looking for simple semi, the first link is a pistol, the second need a well made air tight detent, maybe kind difficult.

[sagthegreat]

the second one looks great
thanks jsr

[wyz2285]

Didn´t know if I should open a new thread, as I only have one diagram to show but it´s a new way to mod a QEV for semi/full operation.
As the diagram shows, the piston housing is not a tube, but conical, so in the initial position, the piston/housing is almost air tight fit so it can be piloted by a small valve, but once open, the fit between them will increase, allowing the piston to self-close(I hope).
For this to work properly, the only critical part is the conical housing, to sharp or to dull, the piston will close too fast or will dump all the air out of chamber.

[cammyd32]

Didn´t know if I should open a new thread, as I only have one diagram to show but it´s a new way to mod a QEV for semi/full operation.
As the diagram shows, the piston housing is not a tube, but conical, so in the initial position, the piston/housing is almost air tight fit so it can be piloted by a small valve, but once open, the fit between them will increase, allowing the piston to self-close(I hope).
For this to work properly, the only critical part is the conical housing, to sharp or to dull, the piston will close too fast or will dump all the air out of chamber.

I don't know about full auto, but semi would probably work.
But as you said I think that the speed at which the valve closes would be an issue because it would allow only a small volume of air to pass into the pilot, meaning that the pilot pressure would be less than the chamber pressure so in effect the sealing face would fail and you would get a very fast oscillating effect on the piston.
I can probably whack up a quick animation if you don't get what I mean, but yea anyway should you get the cone right then it could work, but flow to the pilot would be your main concern.
( btw sorry if I've missed something stupidly obvious here, and have just made myself look like a fool )

[wyz2285]

the speed at which the valve closes would be an issue because it would allow only a small volume of air to pass into the pilot, meaning that the pilot pressure would be less than the chamber pressure so in effect the sealing face would fail and you would get a very fast oscillating effect on the piston.

This is my main concern, if the conical housing is to dull, the piston won´t open for enough time, only a very fast oscillating.
But it can be solved by a sharper housing, the piston will open for longer time.
You are wrong here: it would allow only a small volume of air to pass into the pilot, in this case it will work, you probably meant allow a big volume of air to pass into the pilot
I guess I have to build it to try this concept.