m16-ish, first piston valve nail gun

[beebs111]

$70? on shorty they sell red dots for $5http://www.shortyusa.com

[PVC Arsenal 17]

I'm not familiar with these types. How does it work in full auto?

[saladtossser]

I'm not familiar with these types. How does it work in full auto?

i was surprised when it went full auto when i hooked it to my compressor at only 40 psi

freak accident i suppose, but you wont get it with a blowgun or anything like that, pop offs are special, i guess because the pressure assists in the opening

you better hope your piston is solid and damn well lubricated. the pilot simply opens and closes super fast and so does the piston valve

[PVC Arsenal 17]

Ok I get it now. The pop off exhausts at a certain pressure and with a continuous air supply, the cycle just keeps going. Pretty cool.

[saladtossser]

if you go to a lower pressure, you need a soft padding on the key ring, and the slightest touch to get the same full auto result

[PVC Arsenal 17]

This may be a dumb question, but what is that black thing on the back?

[saladtossser]

oh snap i didnt say, it's a pressure guage

[PVC Arsenal 17]

What size pipe does the piston float inside of?

[saladtossser]

the pilot is 3/4" cpvc, the piston is 1/2" cpvc with tape

[sam_516]

hey nice work on that, how many pumps does it take to pump up??? and you might want to blue glue it caz then you will get more psi into it wich means more power wich means more fun. leaks are such a bitch in these things arn't they, you make it, you think you got it all fixed with no leaks then after another 5 shots you have to pull them apart and rebuild it. i have never seen a pop off valuve used befor, i have all waysed use a modded sprinkler valve, is it hard to pull??? and would it pop after too much pressure (i use 120psi in my guns)
nice work tho and bringing it to skool might sound like a bad idea but hey you didn't get caught so !!!YEW!!! good going

[saladtossser]

1.5 pump = 10 psi
the valve starts to let go at around 90, pump again and it will fire.
what is blue glue? if you are talking about primer, cpvc cement does the same thing as primer, it melts the pipe and fuses two peices as one. ABS cement does too, i guess pvc is a special case.
the valve will go off with the slightest pull when at high psi.

[PVC Arsenal 17]

Those valves r supposed to hold till around 125 psi. How did it work at 40?

Do they make are meant to realease around 50 or so?

[saladtossser]

i pull it... and it's preset at 100... i think with a special tool much like a huge flat head screwdriver with a hole in the center, you can adjust it yourself, but i do not suggest doing that

[PVC Arsenal 17]

I used a pop off valve today and once the pressure was reached the valve opened and stayed open instead of resetting. Does yours work this way or do you actually pull it back and forth super fast to get the full auto result?

Sorry for all the dumb questions by the way, this thing fascinates the crap out of because me its so awesome! I want to understand how it works fully to make my own.

[saladtossser]

i would think you need to make one yourself to understand it
make sure it has close to no pilot volume, i estimate i only have around 3cm cube of pilot volume

oh and yes it will stay open if your volume of air is very high

i guess the flesh on my fingers and the padding on the trigger, combined with the air pressure on the valve and the spring in the valve, acted like a spring, sort of amplifing my fingers movement, only a gentle tug is needed to set it off several times a second

oh and it takes practice to get it right, i have to constantly adjust the spring tension on my piston.

i wanna build the second one but i'm saving cash for some go kart parts