My first Pneumatic - Please give advice

[rikukiakuchiki777]

Hey fellow spudfilians!

I plan on making my first pneumatic marble/paint ball gun. I've researched around, and i don't like with most piston valves and sprinkler valves how you get one shot and then you have to refill the chamber so i started looking for some semi-auto stuff and came upon this: http://www.spudfiles.com/forums/paintba ... 11127.html

I really liked this design, especially the second rifle, but one thing that annoyed me was the actual rifle was bolt action, so i started thinking about modifying that design to make it so, but still using Clide's semi-auto valve.

This is what i came up with:
(2nd time ever posting on a forum, how do i properly insert images lol)

I don't need help with the trigger mechanism, fittings, pipe sizes etc. What I'm unsure about is O-rings, and air hose/air hose fittings. What sort of fittings are needed to tap the air hose into the chamber and valve, if anyone has any tutorials that would be great. Also installing O-rings into the necessary places. Again, tutorials are great.

Lastly, I don't plan to use this is any paintball matches, so the fps is not limited. I plan to buy a shock pump, so hopefully ~280 psi won't be a problem, but say I'm limited to 150psi, what sort of fps am I looking at (If its even possible to tell), and if my air chamber is 1" wide and a 12" long, approximately how many shots will i be able to get out of it. Also, will the size of the air hose limit how much air is fed into the valve in any way?

This is my first pneumatic, so this is a bit far-fetched but I would really appreciate any advice and constructive criticism.

[suburban spudgunner]

I don't really know much about semi-automatics, but I have to say that the fact that you're making one as your first gun is pretty impressive.

The best advice that I can give you (from what I've heard; not sure of how true it is) is to go with a large chamber at a low psi: I'm assuming this holds the same amount of air, but because it's at a lower pressure, it doesn't all escape on the first few shots.

[tghhs]

looks pretty sexy, and i love the super magmun.
yeah i hope u've got alot a practice at machning things, coz it wont take much for a leak, wich will be even more noticable on performance if u want more than one shot.

but yeah if u pull if off it'll be sick, good luck

[inonickname]

If you get a leak in that it will be very inefficient. Also, at those pressures I hope you don't plan to use pvc. And the tiny bore and stroke of shock pumps will give you a very hard time with any real sized chamber.

Good luck though

[psycix]

I'd love to see clide's HEAR-valve being made again. I hope that you have access to a lathe, because you're gonna need it.
There was a topic with a few good links to o-ring tutorials some time ago...



Found it! You're lucky
http://www.spudfiles.com/forums/differe ... 17144.html

[rikukiakuchiki777]

If i use something like 250 psi, how many shots can i expect? I was hoping to make it portable, in that i can fire maybe 20-30 shots before having to refill. Any idea?

[tghhs]

yeah well i can't say for sure, but i reckon ur looking as 3-4 shots maby 5 but the last shot will be lame, just coz not enough pressure.

[john bunsenburner]

I am afraid its a little too hard to make a semi with more than 5 or so shots as one's first gun. Maybe you should start a little simpler of have a full auto paintball/marble cannon but this is really complicated. Also if you do want to make this then i suggest you either use very high rated parts and CO2(liquid so that it boils of to make new gass, that will give you lot sof shots) or if you are willing to pend a bit more you could use liqid propane or butane, same principle as with CO2. Like that you could easyly have over 100shots if you use little gas and have a large aenoth main chamber(id use the bulk tank as the main).

Other wise i suggest you use a compressor as your air supply(or a scuba tank) as anything with less flow would take for ever to fill your chamber and 145psi(10bar) are eanoth for a few(perhaps 4) nice shots with a fairly large chamber. As mentioned you need two chambers but you have that all figured out.

If you manage to finish this project, how ever long it my take, i will not be the only very impressed member, i hope you have lots of fun building this, and if you have any questions queeries or just want to make sure all you are doing is correct, feel free to as any body here either by pm or by making a thread/updating this one.

Can't wait to see this finished.

[psycix]

You wont get much shots out of one chamber.
You will need an high pressure high volume chamber, a scuba tank, CO2 tank or direct connection to a compressor in order to get more then 4 repeated shots.

[Brian the brain]

You can get more shots out of a hammervalve gun.

The pulse of air is simply smaller and shorter.

[john bunsenburner]

BTB, you would need to recock the gun after every shot, I was thinking about how to do this but cant think of a way, i know you have an idea so go on...

[rikukiakuchiki777]

I had a look at some hammer valves, they seem a lot simpler and frankly easier to make. I'm considering replacing the HEAR valve with a hammer valve now, and maybe getting a CO2 tank. Apart from Ebay, where can i grab one of them in Australia. There are some local paintball places, but can you legally buy them from there? Also, how do you refill the tank? where do you buy CO2, and will i need to make some sort of expansion chamber I've heard about when using CO2?