Auto .22 Airgun using JSM's Poppet Valve (Will it work?)

[killerbanjo]

Hey guys, after looking at JSM's HPA Poppet Valve I instantly thought of this little idea, its pretty basic but just wanted to post it here for some tips and thoughts from the experts

Heres the schematic...



So, when the poppet valve gives out its burst of air it pushes the piston (in the blow forward bolt) forward, which in turn pushes the .22 pellet forward and closes the port, as soon as the port is closed the holes on the right hand side of the bolt reaches the opening, when the air rushes throughout the holes it goes around the piston and into the left hand side holes which then launches the pellet. When it de-pressurizes the springs push all the pistons back where they were and the process starts again.



So guys, it would be great to hear some tips and tricks as well as my mistakes pointed out (If any.).

Thanks for reading, Ed.


EDIT:

Re-designed it... Please give opinions

P.S. Blue=Epoxy




EDIT:

Made it again but better, this is assuming that its using a 13 cubic in ninja HPA tank

[Gun Freak]

So guys, it would be great to hear some tips and tricks as well as my mistakes pointed out (If any.).

Move the BFB assy back all the way to the poppet outlet for reduced dead space, and we refer to him as JSR, not JSM. It's ok though I don't get why you don't just put a valve in front of the BFB instead of going through making the hole poppet thing.

[killerbanjo]

Durp i know its JSR (Im lazy and copy paste hence the multi mistakes)

Im doing the "Poppet Thing" because thats the thing that pulses the air and makes it automatic, without it, it would not cycle and would be semi automatic.

[jackssmirkingrevenge]

Im doing the "Poppet Thing" because thats the thing that pulses the air and makes it automatic, without it, it would not cycle and would be semi automatic.

If you don't feel like making it yourself, a QEV + pop-off valve is an off-the-shelf way to get pulsed air (though this is technically less efficient because some air is lost through the pilot).

A word of warning about blow-forward valves, they tend to take quite a beating even at compressor pressures, so make it strong!

[killerbanjo]

JSR, what does the QEV do in the gun, is there a schematic i can look at anywhere (Sorry for being the noob )

[Gun Freak]

Oh ok sorry, didn't realize it was a full auto. The QEV is a quick exhaust valve, it is just a commercial built piston valve.

[killerbanjo]

Ahh i see, i had a look at this page and it explains how it works.

EDIT:

So the method of the QEV and the Popoff would work but it would waist air (and not look as cool) but this method would not, right?

And about the blow forward, would epoxy be enough for the piston or would I have you cut a small section of metal dowle.

[jackssmirkingrevenge]

If you have a look here, I managed to get reliable feeding with 0.22" pellets without having to use a blow-forward breech, using this magazine:



It worked for 100 psi, but at 800 psi the pellets in the mag were pushed up by the pressure so the nose of each pellet stuck in the preceeding pellet's skirt (ooh, sounds kinky ) which quickly jammed the system.

[killerbanjo]

Although thats a cool and simple mag setup im not sure thats what i want (What I would really love is changable mags and decent power) What sort of pressure would i have to run the gun off for equivilant of a shop bought air rifle?

[jackssmirkingrevenge]

Although thats a cool and simple mag setup im not sure thats what i want (What I would really love is changable mags and decent power)

Fair enough

What sort of pressure would i have to run the gun off for equivilant of a shop bought air rifle?

By a "shop bought air rifle" I'm assuming you mean a typical average 10 ft/lbs "adult" air rifle. It depends on a few things, but for a 36 inch barrel and 100 psi I was getting around 370 feet per second with 1 gram pellets, that's around 5 ft/lbs. Assuming you'll use a shorter barrel in the 24 inch range, I would say 300-400 psi would be more than enough.

This implies investing in a paintball tank, or a fridge compressor (or both!) especially if you want the final result to be portable.

[killerbanjo]

Well after looking at fridge compressors i found this one


What sort of pressures do they go up to?

[jackssmirkingrevenge]

What sort of pressures do they go up to?

At least 300 psi, you'll probably get significantly more than that. Personally I would cap it at 450 psi/30 bar tops, more than enough pressure for the power you're looking to achieve. 10 ft/lbs full auto will devastate most targets fairly rapidly.

[killerbanjo]

What pressure can airguns (Compresser guns) operate to? im thinking of using one as the trigger but not sure if it will allow enough airflow or even hold the pressure

[POLAND_SPUD]

these things are called blowguns


IIRC some people have used over 400 psi with blowguns... personally I wouln't pressurise them to more than 300 psi...
most of the blowguns that I've seen are built from some cheap alloy that breaks easily

it seems that this type of blowguns is a bit better but I've never used one

[jackssmirkingrevenge]

I used the second type at 500 psi here and it worked fine, any higher and it started to leak though.