Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 40 users online :: 4 registered, 0 hidden and 36 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Novelty Pneumatic

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
Sponsored 
  • Author
    Message

Novelty Pneumatic

Unread postAuthor: mark.f » Tue Apr 05, 2011 10:34 pm

Figured I would get things out of the way IN THE TITLE. This was meant to be a little time-waster, with not much power, and a unique valve.

In that note, please don't tell me to upgrade to a piston valve, sprinkler valve, hammer valve, metal air chamber, CO<sub>2</sub> filling, etc. :roll:

This thing was cheap, complicated, and required a good bit of hand machining, and it's pretty weak. I fire around pens and marbles indoors at suitable targets.

How it works is a piece of 1/2" SCH-40 is plugged off at one end, and an o-ring is installed above the plug. Above the o-ring, the pipe is ported, and a 1" coupling is centered over the pipe with a modified bushing, with #6-32 stop screws at the end.

A bottle is modified by cutting the threads off the top, and inserted into the coupling, and the stop screws tightened in place. When the bottle is pulled back against the screws, the o-ring seals in the neck of the bottle, and air is pumped in. The bottle is then pushed forward, shoving the ported section of pipe into the bottle and allowing air to flow out the barrel.

Filling is accomplished by a piece of 1/4" hose passing from the front of the bushing and through the back of the 1/2" pipe plug, and epoxied into place. This restricts flow quite severely, but performance isn't that critical.

Construction is explained further in the captions below. Feel free to ask any questions, and bash at your own leisure. :wink:
  • 0

Attachments
IMG_0173.JPG
An overall view of the launcher.
IMG_0174.JPG
A side view, giving a glimpse of the internals.
IMG_0175.JPG
A modified Dr. Pepper bottle. This is done to allow more forward movement inside the 1&quot; coupling, and therefore more flow through the porting.
IMG_0176.JPG
The rear plug. This is some kind of CPVC transition adapter. For what, I don't know, all I know is that it had an end that fit inside 1/2&quot; SCH-40 and a 1/2&quot; CPVC spigot end, and an o-ring. I installed it with #6-32 decapitated machine screws, with moderate compression on the o-ring, with a 1/2&quot; CPVC cap on back. The brass olive is lending some security to the 1/4&quot; fill hose epoxied through the cap.
IMG_0177.JPG
The best view of the internals I have. The o-ring which seals in the bottle neck is visible, but the porting is hidden fairly well by lighting. All it is is four 1/4&quot; holes drilled around the pipe just in front of the o-ring groove. The stop screws grab the lip of the bottle and prevent the bottle from flying away at higher pressures.
mv.gif
Simple cutaway diagram of the valve portion.
mv.gif (982 Bytes) Viewed 976 times
Last edited by mark.f on Tue Apr 05, 2011 11:24 pm, edited 1 time in total.
User avatar
mark.f
Donating Member
Donating Member
 
Posts: 3464
Joined: Sat May 06, 2006 11:18 am
Country: United States (us)
Reputation: 21

Unread postAuthor: Lockednloaded » Tue Apr 05, 2011 10:51 pm

... :? I think I like it if it works how I'm envisioning it, care to draw up a diagram?
  • 0

I love lamp
User avatar
Lockednloaded
Major General
Major General
 
Posts: 1558
Joined: Thu Sep 03, 2009 9:38 pm
Location: Texas, USA
Reputation: 0

Unread postAuthor: JDP12 » Tue Apr 05, 2011 11:17 pm

interesting design.. I understand it now. Fun idea, sort of like a hammer valve in essence. my guess is performance would be limited by the small holes, and air may leak around the outside of the bottle.

Neat concept though, never thought of it before.
  • 0

"Some say his pet elephant is pink, and that he has no understanding of "PG rated forum". All we know is, he's called JSR. "
User avatar
JDP12
Major General
Major General
 
Posts: 1943
Joined: Fri Mar 30, 2007 8:34 pm
Reputation: 0

Unread postAuthor: mark.f » Tue Apr 05, 2011 11:25 pm

Simple diagram added to the original post.

I actually experimented with banging the bottle against the wall to use it like a hammer valve, but, being performance sucks anyway, the projectiles barely left the barrel when doing that. :roll:
  • 0

User avatar
mark.f
Donating Member
Donating Member
 
Posts: 3464
Joined: Sat May 06, 2006 11:18 am
Country: United States (us)
Reputation: 21

Unread postAuthor: Hotwired » Wed Apr 06, 2011 12:49 am

Nothing in pneumatics is new :D

Made a valve like that on my first "cannon"

Seals were electrical tape wrapping and the barrel was a plastic tube with holes cut in the sides and the end closed with hot glue. Chamber was a steel broomhandle.

As I recall, the only thing stopping the barrel from being the projectile was a bit of string...

Still, it was good fun to make and provided entertainment firing pens into the air.

Aside from the clunky pump action nature of the valve it's very simple and easy to make, literally a manual poppet valve.
  • 0

User avatar
Hotwired
Lieutenant General
Lieutenant General
 
Posts: 2599
Joined: Fri Oct 13, 2006 5:51 am
Location: UK
Reputation: 0

Unread postAuthor: mark.f » Wed Apr 06, 2011 8:39 am

Yup, but I bet yours actually had higher performance, as it didn't have a piece of 1/4" OD hose blocking flow. :P

Pretty simple valve, though, like you said. Only time consuming part was cutting the o-ring groove.
  • 0

User avatar
mark.f
Donating Member
Donating Member
 
Posts: 3464
Joined: Sat May 06, 2006 11:18 am
Country: United States (us)
Reputation: 21

Unread postAuthor: Brian the brain » Wed Apr 06, 2011 3:35 pm

Haha!
Great project! :D

I have made a similar valve once, but with the barrel running all the way through the back.
I figured I would not have to fight the pressure.

But friction certainly made it nearly impossible to open fast...and a lot of air leaked through the port..wich doubled as a breech..

So actually...yours IS more powerful!

Oh well..you can't win 'em all.

Nice thinking outside of the box!
  • 0

Gun Freak wrote:
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!!
User avatar
Brian the brain
Moderator
Moderator
 
Posts: 3494
Joined: Mon Dec 05, 2005 2:06 am
Location: Holland
Country: Netherlands (nl)
Reputation: 29

Sponsored

Sponsor
 


Return to Pneumatic Cannon Database

Who is online

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'