| Author |
Message
|
| jackssmirkingrevenge |
Posted: 06/21/2007 22:19 PM Post subject: valveless pellet gun |
|
|
 aspiring machinist

Joined: 15 Mar 2007 Posts: 18051 32498.46 Spud Bux
|
This is an idea I had a while back, which was to dispense with the valve altogether and use the projectile to seal the air chamber, locked in place until it was ready to fire. This would be to all intents and purposes the most effective "valve" happy red? :p I could think of.
The prototype I actually made had a bolt as a projectile stopper and used 0.22 airgun pellets which gave a good seal on the barrel. The performance however wasn't any better than my mini-piston designs so I shelved the idea as not offering sufficient benefits to warrant the awkward method of operation.
The disadvantage is that you need a projectile that's a 100% airtight fit in the breech, which also has to be of strong enough construction to retain the pressure behind it without collapsing. Still, for those seeking ultimate performance, it might be a workable idea.
For more detailed information on using epoxy, check out the how-tos here and here.
Last edited by jackssmirkingrevenge on 09/09/2007 11:04 AM; edited 4 times in total |
|
| Back to top |
|
 |
|
|
 |
| Redcoat |
Posted: 06/21/2007 22:24 PM Post subject: |
|
|
 Bobblehead Doll

Joined: 13 Feb 2007 Posts: 843 369.88 Spud Bux
|
bravo jack, your ideas keep on comng and there always good.I never would have thought of that.That is a good idea maybe for a sniper?
A one shot pistol is pretty annoying (in my books). |
|
| Back to top |
|
 |
| rednecktatertosser |
Posted: 06/21/2007 22:25 PM Post subject: |
|
|
 Colonel

Joined: 22 May 2007 Posts: 601 451.78 Spud Bux
|
So a valveless gun with the most effective valve you could think of? That made me laugh.
But in all seriousness that is a really good idea. I might just make one this weekend... Providing I find money. |
|
| Back to top |
|
 |
| noname |
Posted: 06/21/2007 22:26 PM Post subject: |
|
|
 Mr Vortex

Joined: 10 Apr 2006 Posts: 2644 2483.06 Spud Bux
|
| Knowing you and your epoxy skillz, I think you could make it. Good luck. What kind of projectiles do you have in mind, seeing as they need to seal? |
|
| Back to top |
|
 |
| hi |
Posted: 06/21/2007 22:26 PM Post subject: |
|
|
 Major General

Joined: 01 Feb 2007 Posts: 1632 1425.41 Spud Bux
|
| i think you would have to pull the trigger fairly fast, but it should work, if you can ge it to seal. |
|
| Back to top |
|
 |
| jackssmirkingrevenge |
Posted: 06/21/2007 22:37 PM Post subject: |
|
|
 aspiring machinist

Joined: 15 Mar 2007 Posts: 18051 32498.46 Spud Bux
|
sorry guys but I pressed the "submit" button too early (d'oh!) I actually made a prototype of this, check the edited post  |
|
| Back to top |
|
 |
| Velocity |
Posted: 06/21/2007 22:39 PM Post subject: |
|
|
 Brigadier General

Joined: 07 Feb 2006 Posts: 1049 168.61 Spud Bux
|
Its like a burst disk on steroids! (not really?)
Nice design here... I am surprised that you were able to get it to seal.
It would be interesting to compare this to a burst disk gun of similar size. |
|
| Back to top |
|
 |
| rednecktatertosser |
Posted: 06/21/2007 22:40 PM Post subject: |
|
|
 Colonel

Joined: 22 May 2007 Posts: 601 451.78 Spud Bux
|
| well another one of your wonderful innovations has been put into my "stuff to build" file in my favorites. once again good job jack, like usual. |
|
| Back to top |
|
 |
| jackssmirkingrevenge |
Posted: 06/21/2007 22:40 PM Post subject: |
|
|
 aspiring machinist

Joined: 15 Mar 2007 Posts: 18051 32498.46 Spud Bux
|
| rmich732 wrote: | | Nice design here... I am surprised that you were able to get it to seal. |
It sealed easily without any rubber because the soft lead skirt of the pellet "inflates" and seals agaisnt the barrel. This is after all the same way that brass cartridges seal the propellant casses inside firearms. |
|
| Back to top |
|
 |
| rednecktatertosser |
Posted: 06/21/2007 22:44 PM Post subject: |
|
|
 Colonel

Joined: 22 May 2007 Posts: 601 451.78 Spud Bux
|
| AH so it works off the pricipal of grease seals on a car axle, where its cupped to one side, the side it seals so that it helps hold pressure. thats ingenious. |
|
| Back to top |
|
 |
| shud_b_rite |
Posted: 06/22/2007 0:36 AM Post subject: |
|
|
 1st Lieutenant

Joined: 30 Jan 2007 Posts: 291 510.07 Spud Bux
|
| I like your chamber. Where did you get it? Or how did you make it? |
|
| Back to top |
|
 |
| FreakyShotGlass |
Posted: 06/22/2007 0:51 AM Post subject: |
|
|
 Staff Sergeant

Joined: 02 Dec 2005 Posts: 114 204.26 Spud Bux
|
| You could use a solenoid to hold back the projectile and then apply a current and the solenoid would activate and release the projectile. |
|
| Back to top |
|
 |
| jackssmirkingrevenge |
Posted: 06/22/2007 1:16 AM Post subject: |
|
|
 aspiring machinist

Joined: 15 Mar 2007 Posts: 18051 32498.46 Spud Bux
|
| shud_b_rite wrote: | | I like your chamber. Where did you get it? Or how did you make it? |
I made it myself, as per attached diagram.
| Quote: | | You could use a solenoid to hold back the projectile and then apply a current and the solenoid would activate and release the projectile. |
You'll need a pretty hefty solenoid to achieve that, for a 3/4" barrel at 100 psi it'll have to hold a force of 44 lbs. |
|
| Back to top |
|
 |
| potatoflinger |
Posted: 06/22/2007 7:11 AM Post subject: |
|
|
 Seasoned Spudder

Joined: 02 Nov 2006 Posts: 1126 664.09 Spud Bux
|
| That's a great idea, but wouldn't the pellets wear down the barrel after a while, since they expand to fit the barrel perfectly? It seems like they would scrape the sides the whole way down the barrel. |
|
| Back to top |
|
 |
| lukemc |
Posted: 06/22/2007 7:34 AM Post subject: |
|
|
 Colonel

Joined: 25 Feb 2007 Posts: 569 84.22 Spud Bux
|
| jackssmirkingrevenge wrote: |
| Quote: | | You could use a solenoid to hold back the projectile and then apply a current and the solenoid would activate and release the projectile. |
You'll need a pretty hefty solenoid to achieve that, for a 3/4" barrel at 100 psi it'll have to hold a force of 44 lbs. |
what if you made it like this the solenoid wouldnt have to direcly hold back the pressure

Last edited by lukemc on 06/22/2007 7:35 AM; edited 1 time in total |
|
| Back to top |
|
 |
|
|