SpudFiles

So this is my newest paintball cannon that i built in about two and a half days.

Specs:
Barrel: 43"
Chamber: the pipe itself is about 24" long of 2" sch 40 not including any fittings or the hose
Valve: 1" sprinkler valve modded to trigger by way of blowgun.
Breech Loading with Ball Valve

i will fill with a constant stream of 60psi shop (on board regulator) and the loading is a ball valve breech. I got lucky and found a ball valve with a smaller ball bore than the bore of the barrel. paint balls fit perfect and even with the ball bore being smaller than the barrel i kinda funneled the barrel by sanding it to prevent split paint. i also added a sanded piece of 1/2" pipe (sleeved into the 3/4" pipe) behind the ball valve to prevent the paint balls from rolling back. i calculated the timing of the chamber to fill and it works out that loading should take the same amount of time for the chamber to fill.

the C:B ratio is about 4-1 and GGDT says that i should get about 591fps muzzle velocity at 60psi.

i added some foam rubber to were my shoulder rests for comfort. the whole handle thing can come off because the two tees used to connect it were cut part way so that they are springy so the hose clamp holds them to the pipe by loosening the clamps the handle can come off and the trigger can slide out of it's tee.

i have always been an in line guy and although the cannon is kinda long i wouldn't even think about over under on it.

I have a ball valve attached right after the regulator as well so that i can fill then close the ball valve and be portable (in my own back yard of course) i also left one of the ports on the three way splitter open to adding a schrader by putting a plug in for now if i happen to come across a threaded schrader then i will remove the plug and add it on.

safety is always first so the gun will never be used over 60Psi and only paint balls will be used for ammo. the removable handle piece also is not pressurized along with the camber it is strictly structural.

feel free to ask any questions or give constructive criticism. i am giving the glue 24 hours to dry before shooting anything. Please let me know what you think.

















Damage Pics
the can shots were taken at about 20 feet and the targets at the bottom were shot at from about 150-175 feet. all shots were made with normal paint balls even the can shots you can see were the paint balls exploded as the hit the can putting a pretty hefty dent in it.

Looks standard enough. Obviously what I can say is limited until you've actually tried it, but it should have some potential.

DinerKid wrote:feel free to ask any questions.

How generous. What is the air speed velocity of an unladen swallow?

European or African swallow? (i think thats right.)

funny you ask that it was a bonus question on a history test once and at the time it was an easy 10 points.

you say ggdt predidcts 591pfs. i dont realy think that a sprinkler valve can do that in a two foot barrel. what specs did you put in for the valve? also make sure you have the barrel ID is correct

Ok I got another

What number am I thinking of? I'll give you a hint its between 1 and 100.

Ok seriously now, 591 fps with a paintball I presume sounds a little hot for paintball.

barrel is 43" the chamber is 24". i used the specs that were given for the valve under the libraries section of the GGDT web site. even so i too feel that that is a little high possible 500fps is more like it.

i do not intend to use this for any paintball game. i use it to shoot a target in my back yard.

68?

DinerKid wrote:European or African swallow? (i think thats right.)

No it's not, I'm afraid.
The correct answer is "Approximately 24 miles an hour".

600 fps is probably on the high side, but wouldn't be too inconceivable, particularly with that high C:B ratio.

i used 4-1 for all of my drawings when i was planning it up. then when i ran it through GGDT i used the optimizer tool and it said i was about 1/2" off on the barrel length. i was psyched.

and good one with the whole swallow thing i am glad not only i like Monty python.
let me guess http://www.style.org/unladenswallow/ ????

also with the hose on the sprinkler valve i know it is a short length of hose and that i could have just attached the blowgun right to the valve but what i have found is that when they are directly connected is that the wiggling of the blowgun from pushing the trigger and basic movement causes the whole in the valve to get weak and this usually causes a leak. by using hose i can reduce the amount of stress on the valve. also i had always just used a wrench to put the blowgun into the whole in the valve but by putting it into a drill i got it in with a much snugger fit and it should hold up.

yellow gas tape is also a new thing for me on this cannon. it definitely feels thicker and different from standard while water teflon tape.

DinerKid wrote:let me guess http://www.style.org/unladenswallow/

Possibly. I can no longer remember where I learnt it. I know why I found it out - for the humour of being able to answer the question - but where is a mystery to me.

It definitely feels thicker and different from standard while water Teflon tape.

There's a reason for that... :tongue3:

alright i have a question. say i wanted to make a portable tank for this out of PVC. how could i figure out how large of a tank and what pressure i would need to fill the tank to to get X number of shots. i am looking for the formula. i did a little research on gas laws and i kinda get them but i would be way easier if they were described in the context of pneumatic cannons.

alright so i just fired this cannon in my back yard and let me tell you it is FAST my backyard is pretty big maybe 100 yards long and i couldn't see the paint balls until i hit the target if i miss the target they are gone without me knowing about it. i am really happy with this cannon and i would say it was the most i had ever planned out a cannon. i did drawings and calculations for about a month before hand and used GGDT towards the end for optimizing.

what are you using for a barrel? 3/4 sch40, 3/4 sch80 or what?

I have a question on the blowgun, is there a benefit from having it go back into the gun? Is that just to save the air that you normally waste when triggering it?

no it doesnt go back into the gun. it is just pointed into the handle that is open. the handle is not pressuresed with with the chamer. even if it did go back into the chamber the air from pioleting a sprinkler is minimal

yeah the chamber is in no way connected to the handle area. the blowgun is simply mounted to a piece of PVC that only slides into the tee it is removable so i can adjust the valve if needed. there is a fairly large gap in the pipe were i mounted the blowgun and the air escapes from there. i can't really feel it at all though.

as for the barrel sch 40 and yes 3/4" when i ran the numbers through GGDT with sch80 the fps was way higher so i knew the paint balls would deform so the sch40 was used instead to slow down the pb a little to prevent deforming in flight. even so at the speed the paint balls are going i had to use the hardest shell paint balls i could find to stop deformation from occurring. i am using Diablo heat (sp?). any other suggestions for hard shelled paint balls?

i also forgot to mention sch40 was also going to be my best bet for a smooth transition from the ball valve breech to the barrel even with a small amount of funneling i did.