Pneumatic Pen-gun Project

[jackssmirkingrevenge]

hope this isn't asked before but is it possible to use only a bb as piston ?
this is so cool I will for sure make one(I will tell it's your idea:P)

it has been asked before, and I see no reason why it wouldn't work, but since I was making it a few days before contest entries closed I didn't want to risk it not working.

Wait, are you going to take that to spain hope you don't get caught.

I decided it was best left back home I can build while I'm here, current project is a long barrel 6mm co-axial

[Sticky_Tape]

Will you take it back from spain?

[jackssmirkingrevenge]

It's not in Spain, I left it in the bat-cave

[jackssmirkingrevenge]

Just a little teaser, I'm working on an extended edition of this project, it's not really a "pen" gun anymore with the chamber size doubled an barrel length almost tripled.

I've also changed the valve configuration, the piston is now solid rubber - cut from 1/4" neoprene sheet using a sharpened bit of chamber tube in a drill as an improvised hole saw - that should be more reliable at higher pressures (as long as it doesn't squash up and stop air going to the chamber) and give better flow into the barrel.

If it performs well, the intention is to turn it into a single shot pistol with a hydraulic trigger arrangement, but more on that later. In the meantime, here's the worky bits before the all sealing epoxy:

[ALIHISGREAT]

looks good, i'd be worried about the rubber piston though, maybe lube it up before you stick everything together.

[jackssmirkingrevenge]

I didn't lube it, tight fit but starts moving at 5 psi so it should be fine. My concern is that the pressure will cause it to expand radially and create a perfect seal between the pilot and firing chamber.

I ordered a new shock pump with a gauge that goes to 400 psi as my current one has long been overpumped to oblivion, for now I can only test till 160 psi and I'll do that tomorrow, fingers crossed

[ALIHISGREAT]

well if the rubber is compressible even a little... that may well happen

[brogdenlaxmiddie]

Just thought it was interesting that this topic now has 28000 views......

[psycix]

28001

Thats even more then the global sticky announcements "Grammar" with 16570 views and the "Posting Etiquette" with 6421 views together!

Even the piston valves explained visually thread doesnt beat it with 18120 views.
And larda's 200X hybrid cannon gets beaten with a laughable 11310 views.



But wait, this thead has been beaten by Clides GB semi with 38337 views

[jackssmirkingrevenge]

Just thought it was interesting that this topic now has 28000 views......

And yet, classroom incidents involving teachers suddenly collapsing for no apparent reason haven't increased dramatically

[Sticky_Tape]

And yet, classroom incidents involving teachers suddenly collapsing for no apparent reason haven't increased dramatically

lolz. How about giving a picture showing it's lenth? I don't think the piston will do that I think there would need to be less area on the side of the piston comparred to the rear and front combined. If you don't get that then there would need to be more force on the back and front of the piston to squash it out rather than more area being on the sides squashing it in.

[jackssmirkingrevenge]

Quick test at 100 psi worked great, I'll start another thread for it some time tomorrow.

[chrissilvermancs]

..........

[jackssmirkingrevenge]

great job nice construction but have a few questions first what do u use to fill it, compressed air, helium ect..? and wheres the adapter to fill it with?

Compressed air with a mountain bike shock pump, have a look through this thread.

[xkidxhavocx]

i am going to build one... i just have a few questions...
what did you use as darts?
whats a breech seal?
how far does it shoot?
and how much did it all cost?

.
thanks


MrCrowley: Edited for content (shooting animals)