co2/ air paintball gun

tarmann_90 · Mon Oct 27, 2008 11:21 pm

Ok, i am in the process of making a paintball gun using a combination of c02 and compressed air. My compressor can only go up to 125, and i have figured ill just add co2 as needed. this guns predecesor used a 3" and a 2" chamber, and a 3/4" QEV. .68 cal paintballs work perfectly in a 3/4" cpvc barrel. painballs seem to go on forever- if you can see them leave, and bolts easily punch through sheet metal. Now i am trying to truly make this gun semi-automatic, and have plans for a fully fledged automatic, though its rof will be very slow
So far, i have run into 2 problembs: I need to find out how high i can take my QEV- from detrol/mcmaster, and the semi- auto loading mechanism.
The valve is rated to 140, but i was wondering (besides a hommade piston valve, what kind of valve is pneumatically actuated, holds 200 psi easily- preferably higher, and opens nearly as quickly?
I have seen some "metal" sprinkler valves, but i don't know their names

As far as the semi-auto mechanism goes: it uses a 7/8" compression tee connected to a 3/4" MPT to the QEV. as far as i can tell, all i need is the proper spring to move the bolt back, the one i have is too strong, keeping the air from pushing it forward and closing off the hopper.
I have made another system but it is about a foot long, and can somehow break welded joints with screws. obviously not safe, but it did work something like clides semi auto. any suggestions would be very helpful.

Also, i want to be able to have two blowguns, one the QEV trigger, and the other to remotely control how much C02 is added. Has anyone ever seen a blowgun out there SAFELY handle more than 150PSI?, if so where did you get it?

i will add pictures as i can upload them.

tarmann_90 · Mon Oct 27, 2008 11:43 pm

ok here is the outwardly finished semi auto mech
inside, riding on the compression inserts is a peice of 1/2" copper, a spring pushes the assembly back to allow a paintball to fit, hopefully, the air will cause it to "blowforward", locking off the hopper

tarmann_90 · Mon Oct 27, 2008 11:48 pm

Im not sure if this has been done before (besides the general setup of the semi auto mech.), but for the most part this is a product of boredrom. ok that is it for the moment, if there are any problembs, anyone can forsee, or any questions - feel free

jon_89 · Tue Oct 28, 2008 12:17 am

i have taken my blowgun to 350 psi several times.

littlebro05 · Tue Oct 28, 2008 1:54 am

jon_89 wrote:i have taken my blowgun to 350 psi several times.

Hey jon_89, What kind of blow gun were you using? was it the blowguns used in sprinkler valves?

judgment_arms · Tue Oct 28, 2008 9:11 am

um...
If you've got Co2, why bother with LPA from the compressor?

and if you're using PVC as the main construction material, then you can not use Co2.

as for blowguns, pressure washer spray handles are rated to something on the order of 1500psi.

most spool valve paint guns run at between 120psi and 200psi.
by using a larger dump chamber there's no reason that you could not run a paint gun off LPA.

If I'm understanding the way you're describing your blow-forward bolt idea, it's not going to work, the air will just blow right through.

tarmann_90 · Tue Oct 28, 2008 9:43 am

actually, co2 is only dangerous in liquid/supercooled form- as far as i can tell. it will not be directly injected into the chamber, i know that is asking for trouble. the stabilizer/reg should take care of that, and if it does not, im thinking of more of a remote system(where the co2 is separated from the gun) that will easily give it enough time to expand/ warm up.

as for the blowforward unit, yes im starting to believe you are correct, while i can make work by partialy choking off the flow, i dont want to sacrifice power. i say a piston actuated semi auto by pvc arsenel, and i believe i can use that basis to make a working semi auto, only changing that the piston is hooked up to the tank (i still will be using a QEV to fire)
http://www.spudfiles.com/forums/semi-au ... 16254.html

I chose to make this hybrid of compressed air from a compressor, and to push the 125 to 200 using c02 in order to save money. the chamber is fairly large, bigger than the tank itself, so i dont feel like spending a whole lot just to fire it.[/quote]

jon_89 · Tue Oct 28, 2008 5:31 pm

My blowgun is just your generic one used for modding sprinkler valves.. Yes I know it says 90 psi max.

tarmann_90 · Tue Oct 28, 2008 9:13 pm

Judgement arms: thanks, i never knew those could be taken so high. I understand that LPA is quite sufficient, but i would like to make the gun much more powerful.
The aforementioned semi auto piston will connect to the tank , and ride under the barrel so there is a place for the hopper, here are the two diagrams. I know LPA must mean air- Low Pressure Air? Is there any ideal pnuematic chamber to barrel ratio as in combustions, or even a mathematical formula?, i dont really have the money to test such a thing.
Is there any high-pressure valve that can come near a QEV's performance, besides the hommade pistons(i dont trust modded PVC), and a butterfly valve? Especially ones that can be air actuated like a QEV?

judgment_arms · Tue Oct 28, 2008 9:34 pm

Just call me Judge, and you're quite welcome.

as for the valve, an unbalanced spool valve (blow-forward bolt) would be simple enough to create, the only reason I haven't is I've got three other projects I'm working on already.

here's a an animation:

as I said, shouldn't take to much effort, doesn't even need to be 100% sealed if it's just the bolt and not the valve.

I'm still not sold on the dump-chamber controlled bolt-ram method or "semi auto piston" as you call it.

Correct, LPA stands for Low Pressure Air.

you can make a piston/diaphragm valve using copper tube or even gas pipe.

and as for C/B ratios, Google GGDT, or Gas Gun Design Tool.