semi/full auto shell loading

A place for general potato gun questions and discussions.
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saladtossser
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Mon Sep 25, 2006 12:56 am

Image
a 12 frame animation for you, flex the muscles of my renewed computer...
btw, click on it

the green things are shells/cartridges made of 1/4" OD brakeline
the light red is a 1/8" npt nipple, it has a ramp and a slot for the blue grabber thingy
the blue is the barrel and bolt made of 1/4" OD brakeline, the bolt has a small grabber that slids in a slit in the red
the green box is a modified air cylinder, it will exhaust all the gas when fully open, this cylinder is filled from the exhaust/pilot of a QEV or similar valve, the grey lines in it is a spring
the valve opens to the blue bolt where the 90 degree elbow is, this will need a flexible tubing
you might notice that the green shell might fall out during loading, that is why the ramp is there, so it might fall a bit but slide back to horizontal.
the grey is the ammo, best be a alminum peice put on a drill press and filed to a areodynamic shape

oh u can also have the mag on top and forget the grabber on the bolt, but somebody mentioned austrailian guns and line of fire so... on the side maybe

barrel is ment to be fitted with a little help from epoxy, puddy or jb weld, whatever
Last edited by saladtossser on Mon Sep 25, 2006 1:17 am, edited 1 time in total.
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)DEMON(
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Mon Sep 25, 2006 1:16 am

I am a little confused on how the blue barrel/bolt is supposed to fire at the right moment when the shell is lined up.

Good animation. The design could be built.
Forever dreaming...
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saladtossser
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Mon Sep 25, 2006 1:23 am

when they are lined up, or when they are just about to, the red piston reaches a point where it dumps all of the gas, meaning opening a valve, synchronization is not very important because all piston valves have a small delay in opening time, and all of this is meant to happen fast

i dont think this should be tried with a metal projectile, maybe a plastic bb

this would definitly take some serious dremel work on the 1/8" npt nipple

oh and i did draw a few orings here and there, but i guess they dont show up good

i like simple things, so this thing is only to look awesome when firing, for real fun i'd still use my nail gun, you probably need a spring to aid ejecting and so you can point the gun down without things just falling out the barrel
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)DEMON(
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Mon Sep 25, 2006 1:37 am

What if you just use the exhausted air from the cylinder to fire the projectile?
The more air you put into the cylinder the faster and more powerfull the gun will be.
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saladtossser
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Mon Sep 25, 2006 7:45 am

i thought of that too, either way there is a chance that the air might get trapped and the bolt doesnt return, depends on spring tension, or maybe another cylinder that puches back, and will start charging to chamber again only when it's full

i did this one in school so it sucks
Attachments
Animation of 2 pistons working together, you can see how this is hard to work out
Animation of 2 pistons working together, you can see how this is hard to work out
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Atlantis
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Mon Sep 25, 2006 4:28 pm

I was going to use Galfisk's loader, but this is so much better! I wanna try this out on my hopefully soon to be 3/4' barrel pneumatic.
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saladtossser
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Mon Sep 25, 2006 5:25 pm

stupid me, i dont really need such a complex blow forward, instead use a double action, one end is filled with a calibrated amount of oil, add or remove to adjust return power, the one to be filled with air has a pop off

and i worked out a way to stop posible ammo jams
click the pics

Image

Image

EDIT i just realized how similar this and galfisks design is, i know i've seen his before but i totally forgot about it, does anyone think a moving barrel is better? i didnt think of it that way because i was actually inspired by those nerf assult rifles boltsniper made http://www.boltsniper.com/ , his guns moved the bolt to lock the shells in place

EDIT
off topic, anyone find this banner funny?
http://www.boltsniper.com/Banner/Banner2.jpg

EDIT
i think galfisks idea is harder to actually make, and i still dont like the mag on top look

EDIT
change the direction if u want, it might improve effeciency

EDIT
im too lazy to make the valve, im gonna ask for the prices on a QEV later, should i get a small one like a 1/2" one or like 1", or really small like a 1/4"? and i will also look for a air cylinder, how much do u think it will cost all together?
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POS
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Tue Sep 26, 2006 1:57 am

That boldsniper guy has nice guns, but when you see the video, there is no firepower in them. It is all springaction.
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killagorrila99
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Tue Sep 26, 2006 2:06 am

Why cant anyone just use a simple gravity fed mag?
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saladtossser
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Tue Sep 26, 2006 4:29 pm

POS wrote:That boldsniper guy has nice guns, but when you see the video, there is no firepower in them. It is all springaction.
it's all in the word "Nerf"
Wikipedia wrote:Nerf is a foam-plastic material used in childsafe toys.
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killagorrila99 wrote:Why cant anyone just use a simple gravity fed mag?
you can, but i think spring loaded looks cool, but you have to cut a longer slot on the bottom, OR you can make the grabber on the inside of the bolt so that it doesnt need a slot, you can use a rubber insert so that it holds the shell and seals

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i devised a complex method of delaying the return action, in involves a check valve, and one more pop off valve, this is so that the chamber is emptyed before the barrel is unsealed, increasing shooting power

Image

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This is another similar design
click on it to see it good
Image
note, the rearward rubber seal may be troublesome

also note some possible flaws have been eliminated

the shells should look like this, so they seperate themselves yet always stay upright, the slot in the 1/8" nipple has to be wide though

Image
Image

i would totally stop my massive posts if you guys posted more and faster lol, if this was another post, i would have gotten another 5 spudbux :P
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KVINCEO
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Wed Oct 04, 2006 10:42 pm

this looks pretty damn good, if you can figure all this out to work nice, you could get a pretty good rate of fire i imagine. the barrel movement alone would look awesome. i dont think you would need the ramp to help make the shell horizontal if you make the shell catcher longer and deeper, and have some sort of rachet type thing, that lets the shell move forward but would be knocked out on the return of the bolt.
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saladtossser
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Thu Oct 05, 2006 7:44 pm

i plan for a little pin to lock on to the shells, i will definitly take your advice into consideration, but i cant have it too long, since my 1/4" nipple is only 6" long, i can extend with a coupling but I would have to cut through the coupling too. how long do you think? anyways, once i do a test fire i'll know where to cut my ramp.

i made already bored out my 1/4" nipple with a 3/8" drill bit and cut out the ramp, this thing uses up 1/2 of a cutoff disk per cut

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KVINCEO
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Fri Oct 06, 2006 9:28 am

wouldnt have to be too long, i was thinkin just a coupling, but i doubt if you would even need that much, just enought to hold whatever your shell for a little bit. that ramp looks alot better than what i was pictureing, and alot easier, but id definately consider a coupleing or somthing if the ramp doesent work out.
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