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 44 users online :: 4 registered, 0 hidden and 40 guests


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

Registered users: al-xg, Bing [Bot], Google [Bot], Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

valveless gun, update with new videos

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.
Sponsored 
  • Author
    Message

valveless gun, update with new videos

Unread postAuthor: trollhameran » Tue May 13, 2008 2:27 pm

Ive seen topics made for valveless designs where the ammo is used to seal the barrel so that air cant escape untill a trigger is released letting the ammo through. So i thought id make a prototype as im hoping to use the idea for a shotgun design in the near future. the prototype is basically a short length of copper tube with a whole drilled in it for the trigger (a nail) to go through infront of where the ammo (a potato) will be. it took me literally a minute to make it and it seems to work quite effectively at 110psi, it smashes the potato into very small pieces, bear in mind that this is just using the potato to seal the barrel and the actual gun i make will have rubber seals inside the barrel.

Also im looking for ideas of how i can make the shotgun pump action but so far all my ideas have big flaws in them due to the valveless design, so if anyone has any ideas that would be great.



[youtube]http://www.youtube.com/watch?v=ZEqhdzYb0QQ[/youtube]

[youtube]http://www.youtube.com/watch?v=JG8sGOsj8os[/youtube]
  • 0

Last edited by trollhameran on Thu May 15, 2008 3:45 pm, edited 1 time in total.
User avatar
trollhameran
Colonel
Colonel
 
Posts: 515
Joined: Tue Dec 04, 2007 5:41 pm
Reputation: 0

Unread postAuthor: iknowmy3tables » Tue May 13, 2008 2:43 pm

not that impressive, seals surprisingly well, one problem is the lack of any chamber volume
  • 0


iknowmy3tables
Major General
Major General
 
Posts: 1558
Joined: Fri Dec 15, 2006 3:57 pm
Location: maryland
Country: United States (us)
Reputation: 0

Unread postAuthor: trollhameran » Tue May 13, 2008 3:10 pm

yh i will have a much bigger chamber volume on the gun when i make it but this was just a test to see if it would seal well enough to be feasable
  • 0

User avatar
trollhameran
Colonel
Colonel
 
Posts: 515
Joined: Tue Dec 04, 2007 5:41 pm
Reputation: 0

Unread postAuthor: pat123 » Tue May 13, 2008 3:41 pm

cool, how much air leaks around the potato? it has to be one of the fastest opening and best flow "valves" if it doesn't leak.
  • 0

User avatar
pat123
Colonel
Colonel
 
Posts: 514
Joined: Sat Dec 23, 2006 10:08 pm
Location: S.C.
Reputation: 0

Unread postAuthor: trollhameran » Tue May 13, 2008 3:47 pm

a very small amount of air leaks out but im going to test it in a day or two with a rubber seal inside to see if that stops the leak completely
  • 0

User avatar
trollhameran
Colonel
Colonel
 
Posts: 515
Joined: Tue Dec 04, 2007 5:41 pm
Reputation: 0

Unread postAuthor: jrrdw » Tue May 13, 2008 3:56 pm

Sgort87 and I was kicking this idea around a little bit. I think you may be the first to build a working model. A potato held back 110 psi, how did you pull the nail out? a tow truck??? :shock: Here's what I drew up in paint about a year ago. --

Image
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6538
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: FeLeX » Tue May 13, 2008 3:57 pm

Nice man!! Didn't think potato would seal that good! Make it into a single shot sniper rifle! How much psi were the shots at??
  • 0

I have a signature. In Russia signature has you.
User avatar
FeLeX
Captain
Captain
 
Posts: 310
Joined: Sat Mar 10, 2007 10:45 pm
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: trollhameran » Tue May 13, 2008 4:37 pm

jrrdw: the nail was quite hard to pull out, you could feel there was alot of force pushing against it from the potato. I think what im going to try to do is get a rubber o ring and put it in a coupler then have the barrel one side of the coupler and the chamber the other side so that the o ring is sandwiched in between the barrel and the chamber, hopefully that will help it to seal even better.

FeLeX: it was at 110psi
Im planning on making it into a shotgun but it will have interchangeable barrels so I will most likely make a sniper barrel for it as well.

Possibly going to try to make some custom rounds for it using the same principle as these bottle stoppers Image So that when the chamber is filled the pressure will force the round into the trigger and the round will compress and the rubber will be pushed out so that it seals in the barrel then when the trigger is released the round springs open so that the pressure can push it down the barrel.
  • 0

User avatar
trollhameran
Colonel
Colonel
 
Posts: 515
Joined: Tue Dec 04, 2007 5:41 pm
Reputation: 0

Unread postAuthor: pat123 » Tue May 13, 2008 4:55 pm

I have an idea for the pump action part. have a tube with a 45 degree elbow below the barrel.put an oring across inside the pipe near the top to keep all of them from coming out. put a stick in the other side that seals in the pipe. this is too hard to explain i will post a pic.

i think this would work
  • 0

Attachments
pump.JPG
pump.JPG (14.62 KiB) Viewed 598 times
User avatar
pat123
Colonel
Colonel
 
Posts: 514
Joined: Sat Dec 23, 2006 10:08 pm
Location: S.C.
Reputation: 0

Unread postAuthor: psycix » Tue May 13, 2008 5:59 pm

@ pat123
I think that setup will blow out the "stick", and make it act like a pneumatic ram, and all balls will fly out too if things break.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: Eddbot » Tue May 13, 2008 6:56 pm

what if you had a valve at the end of the barrel that worked on the same principle as a piston pilot, you load the projectile(think of it as the piston without a stopper), then close the valve at the end of the barrel, then pressurize the chamber, the valve at the end keeps the pressure in(like a blowvalve), then when the valve is opened the projectile is fire out the barrel like when a piston exhausts, but without a bumper to stop the piston, launching the projectile, the only problem i can see is finding a valve that uncovers the whole barrel fast enough
  • 0

:edfirst:
User avatar
Eddbot
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 434
Joined: Tue Oct 09, 2007 6:08 pm
Reputation: 0

Unread postAuthor: trollhameran » Wed May 14, 2008 1:05 am

pat 123 i think i have an idea how i could make your idea work, ill draw a design for it then ill post it up here.

Eddbot: do you think you could post a pic of how your idea would be set up so that i can have a look and see exactly how it would need to be made for it to work
  • 0

User avatar
trollhameran
Colonel
Colonel
 
Posts: 515
Joined: Tue Dec 04, 2007 5:41 pm
Reputation: 0

Unread postAuthor: daxspudder » Wed May 14, 2008 1:21 am

so why not just use a burst disk, there is no valve involved, except the fact that you have to pressurize it somehow, like maybe a SCHRADER VALVE...
  • 0

User avatar
daxspudder
Captain
Captain
 
Posts: 300
Joined: Thu Apr 24, 2008 10:22 pm
Reputation: 0

Unread postAuthor: trollhameran » Wed May 14, 2008 1:40 am

to be honest i dont really understand how burst discs work
  • 0

User avatar
trollhameran
Colonel
Colonel
 
Posts: 515
Joined: Tue Dec 04, 2007 5:41 pm
Reputation: 0

Unread postAuthor: Hydra » Wed May 14, 2008 1:49 am

Pretty simple.
A burst disk is made from something that ruptures at lower pressures. WHen that pressure is reached, the burst disk bursts.. fulfilling its final job and all the air comes out. Its supposed to be the best valve in terms of performance and flow, but the worst in cost and management.
Its usually used in hybrids. There is alot of pressure already but the disk doesnt break. Now when you explode the pressurised fuel mix there are huge pressure which break the burst disk.
  • 0

User avatar
Hydra
Sergeant First Class
Sergeant First Class
 
Posts: 131
Joined: Sat Mar 08, 2008 11:58 pm
Location: New South Wales, Australia
Reputation: 0

Next

Return to Pneumatic Cannon Discussion

Who is online

Registered users: al-xg, Bing [Bot], Google [Bot], Yahoo [Bot]

Reputation System ©'