SpudFiles

does anyone know a good way to make a semi auto piston valve. (not from a sprinkler valve) just to plink and scare squirls not kill the cute little things

Check out Poland's Semi Auto MkIII. It can fire and load itself automatically. Typically, with a constant air source, a well and carefully made piston valve can fire semi automatically. Here is my 2 incher going semi auto.
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YES THAT IS GOOD did you read where i said not a sprinkler valve the don't provide good enough air flow

The sprinkler valve is not the main valve. Is is a 2" valve with a 1.5" porting. The sprinkler is only the pilot valve. Sounds like you need to read up on piston valves before you jump on a semi-auto.

oh and i need to know how to build it

This is a How-to Database. The section clearly states (NOT FOR HELP-ME POSTS!). This thread will either get moved, locked, or deleted.

ye i have read about them take a look a mr red rosters tutoralhttp://www.youtube.com/watch?v=vmxaI3_SJCg

Seen his, it is good for small valve and high pressure. Take a look at this tutorial. It depends on what you want to use, pressure, bore, etc. You haven't provided us with any of this info, so it is hard to help you.

yes i really cant prove myself as my only knowledge is you tube and Google i am a middle schooler not an enginer

how can i build a good semi auto piston valve

With patience and research.

Like Gun Freak said, you need to do some more research before jumping in to semi-auto piston valves. You need to know what you are doing, we will not spoonfeed you through the process.

Why do you need a high flow valve to scare squirrel's anyway? The noise from a sprinkler valve pneumatic could be enough to scare them away. Do you even know how a piston valve works?

why ye i do and i have build 3 other cannons all of them have ball valves or a sprinkler valve but my sprinkler valve messed up and the piston is screwed so i can't just dish out 15 dollars every weekend i don't haw a job. a piston valve is simple if you think about it. even i can grasp the concept. in the video i posted a link to i only need a 3/4 in hose barb like the one in the video and i will have a barrel sealing piston valve i am in middle school i am not retarded

We never said you were retarded
Just need to get educated about advanced concepts. A semi-auto piston valve is a big step up from a sprinkler valve or ball valve cannon. I started spudding last year when I was in 8th grade. I think the first post I ever made was a topic about piston valves, and I believe it was MrCrowley himself who educated me on the basic concepts. I advise you do loads of research before you tackle a piston valve, let alone a semi-auto. Just my two cents, I'm not putting you down, only helping.

A moment ago you were struggling to understand how a sprinkler valve would be used on a piston valve. No need to get defensive about it, I was just asking some questions.

a piston valve is simple if you think about it

So is how a car engine works, doesn't mean it is easy to build. Piston valves can be a little tricky the first time you build them, you need to get a 'feel' for how good of a fit the piston will need to be, what makes a good piston, how to troubleshoot certain issues, how much travel you need for flow etc. Once you have a piston sorted out, you just need a 3/2 valve which can pilot the valve, a hopper or magazine for the ammo and that will get you semi-auto. Though, expect to be held down by a compressor. Unless you have a separate pressure tank from the chamber which holds enough pressure to refill the chamber multiple times, you wont get semi-auto from just one chamber fill.

i only need a 3/4 in hose barb ... and i will have a barrel sealing piston valve

Ah yeah, okay, goodluck with that.

take a look at my, NOT very easy to build but works well http://www.youtube.com/watch?v=DeRnZeZps4g

i seriously will... soon the piston moves easily with just the pressure of my mouth and stays sealed at 70 psi i understand what and how to do what i need to do. i can build. sorry if i came off as defensive but this is my second topic and i am the only one in the eighth grade that knows what the word pneumatic means. not even the high school lab teacher knows how to help. it is nice to talk to people who are smarter for a change