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My next projext is under way...

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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My next projext is under way...

Unread postAuthor: Kris.Is.Awesome » Wed Aug 02, 2006 10:08 pm

With the help of BoilingLeadBath, I've figured out what I want to do. I worked the GGDT with him, and got a fairly nice result. 482 fps, which is 328 mph! Not bad for a tennis ball. I'm drawing up plans right now. It's going to be an over-under, with a 3 foot, 4" chamber, a barrel seal "T" valve, and a 4' 2.5" tennis ball barrel. Sounds fun...

Heres the GGDT...

Image


Thanks Boiling...
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Unread postAuthor: noname » Wed Aug 02, 2006 10:27 pm

You're not going to get those results because a tennis ball is bigger than 2.5," you have to squeeze it a bit to force it in. The friction is also a lot more because it's bigger than the ID.
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Unread postAuthor: MrCrowley » Thu Aug 03, 2006 11:26 pm

which piston are you building?im going to build the same as BC's 2" video but ill make it a 3" tee.i put the stuff in GGDT for a O-U design GB gun and i got 353 meters at 601fps is that correct?doesnt sound like it
i need help on how much pilot volume there would be in the 3" piston valve and the flow.

p.s with a piston valve do you let the projectile go all the way down into the piston or do you put something to stop it before the tee?
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Unread postAuthor: Brian the brain » Fri Aug 04, 2006 9:37 am

I read you gotta singe the hairs off of the tennisball to make it fit better.
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Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: mark.f » Fri Aug 04, 2006 9:56 am

Nope. Just buy the cheap tennis balls. They fit better, for some reason. Not only the Wal-Mart balls, but any sort of cheap ball at a sports store.

Also, more friction isn't bad when shooting. That's why badly cut loose potatoes don't work as good as snug, airtight, high friction potato plugs.

Also, the bore on a 2-1/2" SCH-40 barrel is about 2.445", and a tennis ball usually runs around 2-1/2". There's gonna be some squeeze to get the ball in there. But don't worry, squeeze is good.
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Unread postAuthor: huse_spud » Fri Aug 04, 2006 10:06 am

try beer bottles with 2.5" pvc. that would be alot cooler than TBs anways cuz they'd do more damage.
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Unread postAuthor: WOW!! » Fri Aug 04, 2006 10:39 am

MrCrowley wrote:which piston are you building?im going to build the same as BC's 2" video but ill make it a 3" tee.i put the stuff in GGDT for a O-U design GB gun and i got 353 meters at 601fps is that correct?doesnt sound like it
i need help on how much pilot volume there would be in the 3" piston valve and the flow.

p.s with a piston valve do you let the projectile go all the way down into the piston or do you put something to stop it before the tee?

Before you make it out of 3" make it out of 2". I fucked up 2 of them because of the springs, make sure you srpiing is the right lenght.
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Unread postAuthor: Kris.Is.Awesome » Fri Aug 04, 2006 11:12 am

a 3" valve is pretty damn big. I think my 2 will be plenty of flow for the gun.

Here's my concept drawing. (Sorry, phone pic). There's no hose or blowgun on it yet.
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Unread postAuthor: Velocity » Fri Aug 04, 2006 11:32 am

wow... good drawing! You will be blown away by the power of even a 2" piston valve; it just OWNS sprinkler valves/ball valves/ even QEV's!

You really don't need to use a spring... I dont use one on my 4" piston valve (3" porting). You do, however, need a bumper of some sort
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Unread postAuthor: Kris.Is.Awesome » Fri Aug 04, 2006 12:38 pm

rmich732 wrote:wow... good drawing! You will be blown away by the power of even a 2" piston valve; it just OWNS sprinkler valves/ball valves/ even QEV's!

You really don't need to use a spring... I dont use one on my 4" piston valve (3" porting). You do, however, need a bumper of some sort



BLB is machining me a piston, I hope it's going to be one hell of a cannon! If I dont need a spring, I'll just use a foam bumper- if that works.
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Unread postAuthor: Velocity » Fri Aug 04, 2006 1:06 pm

A barrel sealing valve, with a piston that has orings? I have always wanted to do that; it may increase performance a slight bit over a piston without orings.

Make sure that the foam bumper is really strong though. If your piston hits ANYTHING with enough force, someone is going to end up broken, whether it be the endcap or the actual piston. I have had a solid PVC rod piston crack at a 50 PSI firing with my 2" piston valve (1.5" porting)
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Unread postAuthor: beebs111 » Fri Aug 04, 2006 2:09 pm

i think that he is using a chamber sealing piston. why you ask..... because the barrell is bigger than his piston housing :roll: :D
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Unread postAuthor: huse_spud » Fri Aug 04, 2006 2:21 pm

beebs111 wrote:i think that he is using a chamber sealing piston. why you ask..... because the barrell is bigger than his piston housing :roll: :D


the GGDT at the top says its a barrel sealing gun.

i think every seasoned spudder has made a design like this in his lifetime. :lol:

i've been slowly collecting materials for a gun similar to this for about a week now.
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Unread postAuthor: Kris.Is.Awesome » Fri Aug 04, 2006 5:32 pm

huse_spud wrote:
beebs111 wrote:i think that he is using a chamber sealing piston. why you ask..... because the barrell is bigger than his piston housing :roll: :D


the GGDT at the top says its a barrel sealing gun.

i think every seasoned spudder has made a design like this in his lifetime. :lol:

i've been slowly collecting materials for a gun similar to this for about a week now.





It's going to be an absoluteley amazing gun. I may sell it shortly after I build it-
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Unread postAuthor: MrCrowley » Fri Aug 04, 2006 5:49 pm

WOW!! how long would my spring need to be?im going to use a 3"tee ,and a 45mm barrel out for GBs and im going to make a piston out of a pringles can put some rubber on the end and attatch it using a bolt to give the piston some extra weight and fill the can with hard foam or epoxy something that will dry hard,i plan on cutting up a mouse pad and padding the inside of the end cap and put a spring on the end cap or i might put it on the pringles can.
any tips i stayed up late last night looking for good 3" pistons and i only came across the pringles thing :D
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