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| jackssmirkingrevenge |
 Posted: 06/21/2007 22:19 PM Post subject: valveless pellet gun |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 18051
32498.46 Spud Bux
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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 |
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| Redcoat |
| Posted: 06/21/2007 22:24 PM Post subject: |
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Bobblehead Doll
Joined: 13 Feb 2007
Posts: 843
369.88 Spud Bux
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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). |
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| rednecktatertosser |
| Posted: 06/21/2007 22:25 PM Post subject: |
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Colonel
Joined: 22 May 2007
Posts: 601
451.78 Spud Bux
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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. |
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| noname |
| Posted: 06/21/2007 22:26 PM Post subject: |
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Mr Vortex
Joined: 10 Apr 2006
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| 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? |
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| hi |
| Posted: 06/21/2007 22:26 PM Post subject: |
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Major General
Joined: 01 Feb 2007
Posts: 1632
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| i think you would have to pull the trigger fairly fast, but it should work, if you can ge it to seal. |
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| jackssmirkingrevenge |
| Posted: 06/21/2007 22:37 PM Post subject: |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 18051
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sorry guys but I pressed the "submit" button too early (d'oh!) I actually made a prototype of this, check the edited post  |
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| Velocity |
| Posted: 06/21/2007 22:39 PM Post subject: |
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Brigadier General
Joined: 07 Feb 2006
Posts: 1049
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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. |
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| rednecktatertosser |
| Posted: 06/21/2007 22:40 PM Post subject: |
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Colonel
Joined: 22 May 2007
Posts: 601
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| 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. |
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| jackssmirkingrevenge |
| Posted: 06/21/2007 22:40 PM Post subject: |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 18051
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| 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. |
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| rednecktatertosser |
| Posted: 06/21/2007 22:44 PM Post subject: |
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Colonel
Joined: 22 May 2007
Posts: 601
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| 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. |
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| shud_b_rite |
| Posted: 06/22/2007 0:36 AM Post subject: |
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1st Lieutenant
Joined: 30 Jan 2007
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| I like your chamber. Where did you get it? Or how did you make it? |
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| FreakyShotGlass |
| Posted: 06/22/2007 0:51 AM Post subject: |
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Staff Sergeant
Joined: 02 Dec 2005
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| You could use a solenoid to hold back the projectile and then apply a current and the solenoid would activate and release the projectile. |
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| jackssmirkingrevenge |
| Posted: 06/22/2007 1:16 AM Post subject: |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 18051
32498.46 Spud Bux
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| 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. |
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| potatoflinger |
| Posted: 06/22/2007 7:11 AM Post subject: |
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Seasoned Spudder
Joined: 02 Nov 2006
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| 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. |
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| lukemc |
| Posted: 06/22/2007 7:34 AM Post subject: |
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Colonel
Joined: 25 Feb 2007
Posts: 569
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| 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 |
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