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Marble semiauto

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Marble semiauto

Unread postAuthor: Copperboy » Wed Aug 22, 2007 12:35 pm

Image

I'm not sure if this si the correct section to post this in, but since it's almost completed...:wink:

My slowly evolving project has finally reached a point where I can test the loading mechanism live. I know it looks like crap but with some paint and a proper trigger (right now I just plug a female quick in and out) it will get more attractive.

THE RIFLE

Loading:
A coaxial piston is attached (or extended) by a rod all the way down to a "paddle" at the breech. When the magazine is locked in place, gravity force the marbles into the breech. The tight space only allows for one marble falling all the way down into the T-fitting, where a small notch holds it in place. When fired the "paddle" seals of the marbles above, thus preventing burst effect.

Down the T http://i103.photobucket.com/albums/m128 ... G_0790.jpg

Preliminary magazine (holds 5 marbles) and it's socket (note, since the "paddle" doesn't seal of air very well, the magazine need to be pretty airtight, the o ring can be spotted in the above image, and to keep the magazine from taking off, it needs to be held down. Better solution to come)
http://i103.photobucket.com/albums/m128 ... G_0788.jpg

The mechanism is copied from Galfisk semi-soft, but scaled up a bit.

Various specs:
The barrel is 110cm, and cal. 16mm. Total length's 130cm. Final magazine capacity 10 marbles. When I designed this gun, I didn't really cared about chamber size. If it got small, it would recharge faster. If it got big, it would have more power (to an extent). But I think I landed some where in between :P .

A handmade drawing in swedish, but I think you'll understand it.
http://i103.photobucket.com/albums/m128 ... itning.jpg
Internal parts before soldering..
http://i103.photobucket.com/albums/m128 ... C00169.jpg
http://i103.photobucket.com/albums/m128 ... C00168.jpg
http://i103.photobucket.com/albums/m128 ... G_0533.jpg
The piston
http://i103.photobucket.com/albums/m128 ... G_0535.jpg

Videos:
Me, testing the mechanism
http://s103.photobucket.com/albums/m128 ... t=test.flv

Shortrange (it was quite loud at 8bar, so I made a shitty silencer :lol:
http://i103.photobucket.com/albums/m128 ... G_0786.jpg )
http://s103.photobucket.com/albums/m128 ... test-1.flv

I got tired of the silencer, hehe...
http://s103.photobucket.com/albums/m128 ... bottle.flv

Please feel free to comment, and credits to Galfisk who I copied some bits from.
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Unread postAuthor: spud yeti » Wed Aug 22, 2007 12:49 pm

Looks really ghetto, but the concept is good, and any semi-auto is impressive.
What is the ROF that it can achieve?
Good work though, and with some cleaning up, it can look even better! :wink:
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really good quote/phrase here
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Unread postAuthor: hi » Wed Aug 22, 2007 1:07 pm

dude, what did you do? throw it in a fire? thats thing very badly burnt. rather than painting it and making it look even worse, just take a dremal and a polishing wheel and make it shinnny, it will look so much better.

it is nonetheless a very good design and its good that you tryed to make a semiauto. not many people (including myself) have made one.
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"physics, gravity, and law enforcement are the only things that prevent me from operating at my full potential" - not sure, but i like the quote

you know you are not an engineer if you have to remind yourself "left loosy righty tighty"
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Unread postAuthor: potatoflinger » Wed Aug 22, 2007 1:08 pm

That looks pretty nice, it also looks like it has a decent amount of power too :D
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It's hard to soar with eagles when you're working with turkeys.
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Unread postAuthor: mike1010 » Wed Aug 22, 2007 1:17 pm

its nice but may be hard to hold and kind need polishing as said above
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Unread postAuthor: VH_man » Thu Aug 23, 2007 6:54 am

i like that idea. if i ever make a marble sniper, ill make it semi auto now...... thats quite the simple mechanism.

thats simply crazzzy. if you could change that chamber, it would be perfect, only problem i see with the design is the fact the breech leaks, but that can be fixed. its an ingenious design, and i wish you well for its improvements.

this was one of those things where i saw it and said "WHY DIDNT I THINK OF THAT!"
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Unread postAuthor: Copperboy » Fri Aug 24, 2007 4:09 am

Haha :lol: Yeah, maybe I shouldn't waste money on paint, it's black anyway :wink:

The ROF is as fast as I can manually fire it right now, but I plan a better trigger device soon. And yes, it has a lot of power although the accuracy is rather bad.

This thing only weighs about 5kg, and it's actually pretty easy to aim and the balance is perfect. But of course a front grip of some sort would be nice.

As for the leaking breech, I may add an o-ring "around" the magazine instead of just one facing the rim so to say.
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Unread postAuthor: mark.f » Fri Aug 24, 2007 6:03 am

I seem to remember you posting the progress on this cannon a while ago. Was that the same cannon?
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Unread postAuthor: Copperboy » Fri Aug 24, 2007 7:41 am

Yes, it is :wink:
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