This is my second big air cannon project. I wanted to make a bolt system and in addition to that have changable barrels. I ended up with a finished product that Im pretty satisfied with. The only thing I don't like are the purple primer stains from sloppily applying the primer.
Here it is
And now some specs:
Chamber volume:5000cc's (estimate)
Barrel: 1 inch PVC
Barrel length: 5'
Ammo: Super balls/bouncy balls and potato's
Action: bolt action
Main Valve: modified sprinkler
Pilot: blowgun
Fill valve: Shrader
average operating pressure: 60 psi
Max pressure:100 psi
Chamber: 3 inch PVC
Chamber length: 2' 3"
Ammo:
The Valve:
Here a closer look at the main valve. Note the crap load of epoxy I used trying to seal the leaks. Advice: if you find leaks in your modded valve where the nipple meets the valve, seal it with epoxy from the inside not the outside as I tried at first.
The bolt opened:
And closed:
The thing Im truly proud of on this gun is the bolt. Unlike most homemade bolts were you need to force the projectile into the barrel after it is opened with this one I just drop the ball in, close the bolt and its ready to fire.
shooting a frozen potato at 1/4 inch ply wood... I honestly didn't expect this to happen...
[youtube][/youtube]
DAMAGE PICS!!!!!
Posted: Sat Jul 23, 2011 1:19 am
by jsefcik
Why is there a hose for the scrader valve? just put it in directly into the air chamber
And with a hose connecting to your sprinkler valve your losing power , just put the blowgun directly into your sprinkler valve,
But other then that nice build!!!!
Damage pics=)?
Posted: Sat Jul 23, 2011 1:35 am
by pneumaticcannons
I put the hose there for accesability mainly but now that you mention it I should have done that. thanks for the reply!
Posted: Sat Jul 23, 2011 1:43 am
by Gippeto
Ya know...I've never seen a pressure rated reducer that looked JUST like the DWV ones. Where did you get those?
OR, perhaps they're NOT rated and should be replaced?
Looks like you may be using a schrader from a tire valve stem? Hose is secured with zip ties??
Would advise you to look for a "thread in" type schrader. Check at a hardware store, or where they have pressure tanks and associated fittings for water wells. Should be able to find it...a couple bucks and it's clean looking.
Hose going to the blowgun isn't a real issue. Personally, I would use braided hose.
Posted: Sat Jul 23, 2011 9:47 am
by pneumaticcannons
I've seen these parts on many other cannons and am pretty sure that they are presure rated. Also the reason the hose connects to the scrader is that that was all I had on hand but now that you mention it I guess I could change it
Posted: Sat Jul 23, 2011 4:38 pm
by MrCrowley
Those bell reducers are commonly non-pressure rated but do exist in a pressure rated form so what you need to look for is "NSF-PW" on all your pipe and fittings. If it says NSF-PW, they're rated.
You can also look up the ASTM numbers and they will also tell you but are a bit more difficult to find information on.
Posted: Sat Jul 23, 2011 5:04 pm
by pneumaticcannons
Iv'e pushed this gun up to 100psi and actually dropped it at that pressure accidentally. So will people please replying about the reducers and if their pressure rated of not!
Posted: Sat Jul 23, 2011 8:50 pm
by saefroch
Pressure vessels have greater structural integrity when pressurized. That's part of the reason soda cans are pressurized.
Posted: Sat Jul 23, 2011 11:06 pm
by jackssmirkingrevenge
saefroch wrote:Pressure vessels have greater structural integrity when pressurized. That's part of the reason soda cans are pressurized.
Even non-carbonated drinks like iced tea get a dose of nitrogen before being capped, partly to help keep an inert atmosphere in the headspace and partly to add rigidity for packing purposes.
In the case of PVC however, dropping it under pressure is not a good idea.
Posted: Sat Jul 23, 2011 11:13 pm
by pneumaticcannons
As I said before, I ACCIDENTALLY dopped it.
Posted: Sat Jul 23, 2011 11:23 pm
by jackssmirkingrevenge
Not meaning to diminish your achievement, for a second major project it's a nice effort. All the talk of DWV is simply to ensure your safety, you don't want to become another cautionary tale like frog boy.
Also, ultimate.
Posted: Sun Jul 24, 2011 2:42 am
by FreaK_with_GuN
First of all -----> Good Gun
I hope you know that bouncingballs work in two directions and it hurts verry verry heavy when a bouncingball hits you.....
i hit myself with a hotgluebullet at 160psi from 10 meters away the results are a blue leg and verry much pain........
Greez
Posted: Sat Aug 06, 2011 12:00 pm
by pneumaticcannons
Ok everybody so thanks for your concerns about the dwv parts and I will be replacing the entire chamber next summer. Look out for the new topic!
Posted: Thu Aug 25, 2011 5:14 am
by pneumaticcannons
FreaK_with_GuN wrote:First of all -----> Good Gun
I hope you know that bouncingballs work in two directions and it hurts verry verry heavy when a bouncingball hits you.....
i hit myself with a hotgluebullet at 160psi from 10 meters away the results are a blue leg and verry much pain........
Greez
Nah don't worry man The balls explode on impact.(sounded wrong) A hot glue bullet!?!? gotta try that~jk
Posted: Thu Aug 25, 2011 8:45 pm
by jhalek90
Bouncy balls will explode on impact, most of the time.
Every once and a great while I've had one bounce.
Luckily I've never been hit by one... Just make sure you shoot in a safe area and your golden.
