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Pneumatic Pen-gun Project

Unread postPosted: Thu Apr 26, 2007 1:52 pm
Author: jackssmirkingrevenge
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 :D

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.

Interesting in making something similar? Check out the how-to ;)

How it works:

Image

For more advanced versions, check out:

Pen Gun v2

Pen Gun Deluxe


A couple of videos (on their side, thanks to my technologically inept sibling :roll: ) :

Update 29/04/2007: Test at 300 psi with nail darts:

[youtube]http://www.youtube.com/watch?v=80GtrWXQmo0[/youtube]


[youtube]http://www.youtube.com/watch?v=VLaRTjhNXm4[/youtube]


Update 27/04/2007: I improvised a cap firing mechanism by sticking a few airsoft BBs in the pen cap, it works! :D

[youtube]http://www.youtube.com/watch?v=9Tios3ZcJqI[/youtube]


[youtube]http://www.youtube.com/watch?v=pbNUn1IRRBQ[/youtube]


[youtube]http://www.youtube.com/watch?v=Z14jAg4m4DA[/youtube]


I'll let the photos and diagram do the rest of the talking:

Image

cutaway diagram

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parts before final assembly

Image

piston and breech closeup

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lead shot in vernier for scale

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"closed" configuration with cap over muzzle

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"open" configuration with cap over schrader

Unread postPosted: Thu Apr 26, 2007 2:18 pm
Author: Hotwired
:lol:

I had to watch those clips a couple of times because I couldn't tell if it had fired or not.

Excellent work making such a tiny launcher :)

Unread postPosted: Thu Apr 26, 2007 2:24 pm
Author: Freefall
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.

Unread postPosted: Thu Apr 26, 2007 2:24 pm
Author: jackssmirkingrevenge
Yeah, the videos are shite, sorry. I'm trying to make some better ones as we speak.

Unread postPosted: Thu Apr 26, 2007 2:27 pm
Author: jackssmirkingrevenge
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

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?

Unread postPosted: Thu Apr 26, 2007 2:47 pm
Author: mega_swordman
You're just full of ideas arn't you. Seriously, I need to state that you are a spudgun revolutionary. :notworthy:

Unread postPosted: Thu Apr 26, 2007 3:00 pm
Author: CpTn_lAw
Do you have any idea of the muzzle velocity achieved by your launcher at 200 psi with a 2mm lead sinker?

BTW: very clean, very cool gun.

Unread postPosted: Thu Apr 26, 2007 3:08 pm
Author: jackssmirkingrevenge
Thanks for the compliments :)

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 :D

Unread postPosted: Thu Apr 26, 2007 3:41 pm
Author: super spuder
:lol: 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.

Unread postPosted: Thu Apr 26, 2007 3:50 pm
Author: jackssmirkingrevenge
super spuder wrote::lol: 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...

Unread postPosted: Thu Apr 26, 2007 3:59 pm
Author: super spuder
kool. i would never have the patients to fidle around with somthing that small :?

Unread postPosted: Thu Apr 26, 2007 4:06 pm
Author: lukemc
very cool! you should keep it loaded and in your pocket just incase someone wants to borrow a pen :wink:

Unread postPosted: Thu Apr 26, 2007 4:15 pm
Author: jackssmirkingrevenge
super spuder wrote:kool. i would never have the patients to fidle around with somthing that small :?


give it a few years *chuckle*

Unread postPosted: Thu Apr 26, 2007 5:10 pm
Author: rna_duelers
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?

Unread postPosted: Thu Apr 26, 2007 5:16 pm
Author: PVC Arsenal 17
You've inspired me! Now I have no choice but to make one. Thanks a lot...