full auto idea

[finland66]

Hello spudfiles!

This is my second post.
And I get an idea of full auto gun, but I need to know does it work. By the way I help with magazine to feeding full auto.
Thanks for the help

[jackssmirkingrevenge]

Yes and no.

It is a stepped piston valve like a pop-off, however you have inverted the sealing surface, and I can tell you from experience that this will either buzz like an angry wasp or slowly leak like an ego deflating.

If you want a design that can be tuned to go dakka dakka dakka, go for this http://www.spudfiles.com/forums/rattles ... 17831.html

[apocavorme]

well, i built a variation of this concept some time ago and it works fine. The diference is that my trigger is a valve in the pilot area. The spring that i use make the valve opens at 50 psi, but with a stronger spring you can make it open at higher pressures. The inverted sealing face is not a problem, as long as you respect the ratio of the piston areas.
Here are the videos:

[finland66]

Thanks!

I get an other idea I wil post it soon

[jackssmirkingrevenge]

The inverted sealing face is not a problem, as long as you respect the ratio of the piston areas.

Hard to do. Let's take a 1 inch piston with a 0.5 inch port.

if the pressure comes from the port, the area once the piston "pops" goes up to 400% of the original which the spring was holding.

Keeping the same ratios but inverting it as the subject of this thread, the increase in area is just 133%.

This means that for the inverted configuration, you need a port diameter very close to piston diameter. This means that the air dumps very quickly, leading to a very high rate of fire.

[apocavorme]

yes, the port diameter needs to be close to piston diameter. My configuration is 19mm diam piston and 15mm diam seat. The rate of fire can be controlled with a asmall ball valve on the input.
In the first video i used a regulated to 100 psi source and in the second a 850psi (co2 unreged) source; with the regulated source the rof was slower, and with the unreged co2 i start openin the valve (the rof statrs slow) and when its fully opened the rof is very high.
When i get a spring stronger enouth to open at 100 psi, i think the rof will decrease a little.
Yes the air dumps quickly, but, isn't it good?
So, if you can find materials to build a seat with a diameter close to the piston diameter, its not a bad idea?

[finland66]

Hi

I drawn an new idea and take picture of it

does this work? who knows

http://s1342.photobucket.com/user/airca ... 3.jpg.html

[jakethebeast]

probably yeah but those o-rings are real PITA to get work well enough

[jackssmirkingrevenge]

I hadn't seen the videos, good stuff - is there a diagram somewhere on spudfiles?

Yes the air dumps quickly, but, isn't it good?

Yes and no... if it dumps quickly, then it cycles very fast, too fast for any reloading mechanism to keep up with. Have you actually tried it in conjunction with a magazine feed?

[finland66]

hi

I didn`t test it but i can use flow controller on that so it isnt so quick dumping

Edit o ring on piston would be floating pneumatics on nylon piston and on the barrel there not gona be o ring becose i found pipe thath fits perfecly inside barrel

[apocavorme]

Finland66:
In theory it will work, but in real world a little variation on the dimensions and spring force may be the diference of working or not. why dont you start with standard parts?

JSR:
Not posted here yet, but soon will...
About the magazine, i'm in the second try (the first did not work) .

[finland66]

Hi

I have start with standart parts. I've made coaxial and piston launcher, now i want machine gun

[apocavorme]

i see, but what i say is make a machinegun with standard parts; if you simply close the pilot area of a qev and put pressure there, if the piston is oringed, it is a machinegun. the rest is loading mechanism.

[finland66]

Thanks

Or I can use qev with pop-off valve