Posted: 04/26/2007 12:52 PM Post subject: Pneumatic Pen-gun Project
aspiring machinist
Joined: 15 Mar 2007 Posts: 18058 32513.12 Spud Bux
Is this the smallest co-axial pneumatic yet?
Construction is all metal, with the main chamber being the 6mm I/D brass tube I normally use as a barrel for airsoft launchers. The barrel is 5 inches long, which set the dimensions for the rest of the device, end result is something a little longer than your average pen but not too far off. The barrel is 2.5mm (0.098") caliber, unfortunately the closest lead shot I have is 2mm wide so I need to use tissue wadding.
No chrono results yet, so far I've tested it to 400 psi, at which point it developed a small leak so I repaired it and limited myself to 200 psi for now. Still, high pressure testing is on the cards some time in the future
Also on the agenda is a proper firing mechanism which will basically consist of a pin inside a pen cap that will allow the device to be fired by applying thumb pressure on the cap which will in turn open the schrader and pilot the piston.
When I first saw the title, I read it as "Pneumatic penguin", and wondered what you were doing with small flightless birds. Then I clicked the link and all made sense.
Nice work, looks good. Have you considered using a presta valve instead of a schrader? You don't need a pin to depress a presta stem.
Joined: 15 Mar 2007 Posts: 18058 32513.12 Spud Bux
Freefall wrote:
When I first saw the title, I read it as "Pneumatic penguin", and wondered what you were doing with small flightless birds. Then I clicked the link and all made sense.
I know! I kept looking at the title from the corner of my eye while typing out the post, convinced I had written "penguin" by mistake hehe
Quote:
Nice work, looks good. Have you considered using a presta valve instead of a schrader? You don't need a pin to depress a presta stem.
Thanks very logical suggestion... though can a presta handle the sort of pressures I'm likely to subject it to?
Joined: 15 Mar 2007 Posts: 18058 32513.12 Spud Bux
Thanks for the compliments
Quote:
Do you have any idea of the muzzle velocity achieved by your launcher at 200 psi with a 2mm lead sinker?
I've given up trying to get a chrony reading, the projectile is too small and the chrony isn't seeing it ah well, as far as power goes, I can tell you it will go clean through a folded piece of A4 paper at 200 psi
what drove you to make a gun that is soo small that it can only shoot through paper? not that i am saying it is stupid, i actually think it is quite cool.
Joined: 15 Mar 2007 Posts: 18058 32513.12 Spud Bux
super spuder wrote:
what drove you to make a gun that is soo small that it can only shoot through paper? not that i am saying it is stupid, i actually think it is quite cool.
Fair enough, I usually aim for high power, but felt like something a little different. Also, this is only 200 psi, I'm sure things will get a little better at 400...
Hahahah,a few year nice call..But this is really cool,look out you don't hit some one or yourself in the eye it would cause some damage.400 PSI!Nice what gas source are you using?
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ah well, as far as power goes, I can tell you it will go clean through a folded piece of A4 paper at 200 psi 
