QEV and shock pump questions

[SP00K]

I plan on making a coaxial pistol. I want to make a qev like this one: [youtube][/youtube] but I do not fully understand how it works. I thought about using a modded sprinkler valve but it seems just too clunky for a pistol. I also considered just using a blowgun (which is probably what I'll end up doing). I am going to use 1" pipe for the chamber with a .25" diameter barrel.

That's where the shock pump question comes in. I wanted to mount the shock pump on the bottom of the underside of the gun. But I recently read a thread where someone's shock pump exploded when filling a chamber over 60cc in size. Could someone fill me in on shock pumps a bit?

[jackssmirkingrevenge]

Have a look at this project as an example of using the a blowgun as both valve and chamber.

Referring to this exploding shock pump story, I would say it was an isolated incident and really a 60mL chamber is a little too much for a shock pump, I usually use mine for less than one fourth of that - even if the pump doesn't explode, your arm will fall off from the effort.

[POLAND_SPUD]

it's a piston valve

[FighterAce]

a 60mL chamber is a little too much for a shock pump, I usually use mine for less than one fourth of that - even if the pump doesn't explode, your arm will fall off from the effort.

Yep, I totally agree with that now... that shock pump just wasnt built for the kind of use it got I'm definitely overbuilding my new pump so most of the components can handle more then triple the pressure I intend to use.
The pump in the incident was not overbuilt at all... it was made for 400 psi max and I took it to the limit every time I used it, thats it.

If you go with something less then 15cc, like JSR said, I think that shock pump would do just fine.

btw. it took me about 150 strokes with that pump to reach 400 psi... my arm didnt fell off but after a few refills it did And dont think I was using all that volume for just one shot, it was a crude ball valve multi shot but it worked... got about 7 shots per fill.

[Lockednloaded]

for a pistol, I think you should go with a .25 barrel and a .5 chambered co-axial, I recently built a pistol with a .5" x 12" chamber and 5/16" x 12" barrel. It is a co-axial configuration it take 20 pumps to reach 150 psi and is piloted by a blow-gun

[Stolly32123]

if only the video was in english

[jackssmirkingrevenge]

if only the video was in english

Surely it's fairly easy to understand even without sound.

[lemming124]

piston valve
spring resets the piston and acts as a bumper, there are also quite a few o rings, to reduce pilot volume I think.

[wyz2285]

the video is a self close piston valve,i have watched it a lots of times