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Mini 0.22" coaxial

Unread postPosted: Tue Jan 12, 2010 11:54 am
Author: jackssmirkingrevenge
Might as well post it here :roll:

This was intended as a cartridge as part of this researchbut didn't perform well in that context, however as a launcher in its own right it works a treat and is probably the smallest 0.22" pellet gun ever made :)

A couple of damage videos with 0.22" airgun pellets at 800 psi, courtesy of my home made fill station.

[youtube]http://www.youtube.com/watch?v=TPX4mYso1Ps[/youtube]

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

Finished article compared to a 0.303" rifle cartridge

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Parts before being put together, it's worth noting that I didn't use any fancy epoxies here, just plain Araldite, and the piston is simple a piece of thick rubber cut using a sharpened section of chamber tubing:

Image

Diagram of the internals:

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Unread postPosted: Tue Jan 12, 2010 12:25 pm
Author: POLAND_SPUD
hmmm maybe it is just too small and too efficient.... you know what I mean right ? if you could deisng a slightly larger version of it with a considerably larger chamebr volume there is sure to be more recoil

but I still think it isn't very practical.... though I really like your idea to use a QC to build valves launcher... I think it could be coupled with a simple pressure dependant loading mechanism

Unread postPosted: Tue Jan 12, 2010 1:18 pm
Author: jackssmirkingrevenge
POLAND_SPUD wrote:hmmm maybe it is just too small and too efficient.... you know what I mean right ? if you could deisng a slightly larger version of it with a considerably larger chamebr volume there is sure to be more recoil


Cartridge capacity is certainly an issue, the more compressed air you have then the more you keep pressure up in the barrel/breech system delivering a bigger impulse to the cartridge. In this case, the volume of air is barely bigger than the volume of the cartridge "barrel" so pressure dissipates very quickly, hence the distinct lack of blowback.

but I still think it isn't very practical.... though I really like your idea to use a QC to build valves launcher... I think it could be coupled with a simple pressure dependant loading mechanism


A "valveless" cartridge on QC principles as illustrated below is certainly within my construction capabilities, the pellet skirt would take care of sealing - but I doubt i would be able to make it in the quantities required of a practical cartridge launcher. Maybe the lathe-owning crew could turn it into a feasible proposition ;)

Unread postPosted: Tue Jan 12, 2010 2:40 pm
Author: POLAND_SPUD
well it could be used on cartridges but I was refering to a valveless (and cartridgeless :wink:) gun

Unread postPosted: Tue Jan 12, 2010 3:12 pm
Author: jackssmirkingrevenge
POLAND_SPUD wrote:I was refering to a valveless (and cartridgeless :wink:) gun


The problem of having this system in a self-contained launcher is reloading, assuming you don't want to have to fill it for every shot - in the latter case though, it would be no better than a burst disk launcher.

Unread postPosted: Tue Jan 12, 2010 4:54 pm
Author: psycix
Nice mini-pengun!
It has a surprising amount of power for its size, but hey, that's the reward for 800 psi.

Maybe the lathe-owning crew could turn it into a feasible proposition :wink:

Is it me or do you keep dropping these suggestions with a wink?

Sorry, I'm not convinced that a cartridge design is the most practical mechanism.
Besides all the hassle of manually loading and filling each cartridge, the feeding system becomes hell as you will not only have to feed them, but are also required to eject them.
For powder guns, its a need (feeding powder into a chamber like we do with air would be... difficult and unwise) but as long as we are playing with gases, we can easily refill the chamber with fresh propellant.

EDIT:
The diagram you posted is... hard to do unless pellets can seal.
The orange balls...
If they are balls from a QC, then it won't seal, unless the skirt of the pellet seals.
If they are an o-ring, then the piece of pipe after it will be cut off.

So, can pellets seal 800 psi by the use of the skirt?

Unread postPosted: Tue Jan 12, 2010 7:20 pm
Author: twizi
is this gona be a new marker gun

Unread postPosted: Tue Jan 12, 2010 9:53 pm
Author: theBOOM
Good job on the mini build, what do you use to make the tiny seals on the piston and at the end of the barrel, some type of rubber?

Unread postPosted: Tue Jan 12, 2010 11:53 pm
Author: jackssmirkingrevenge
psycix wrote:Is it me or do you keep dropping these suggestions with a wink?


Just throwing spaghetti at the wall, maybe some of it will stick ;)

Sorry, I'm not convinced that a cartridge design is the most practical mechanism.


Fair enough, I'm aware this is mostly a personal obsession with flying brass hehe

The diagram you posted is... hard to do unless pellets can seal.
The orange balls...
If they are balls from a QC, then it won't seal, unless the skirt of the pellet seals.
If they are an o-ring, then the piece of pipe after it will be cut off.


Balls! Though slots cut for an o-ring could conceivably work as well, and be less likely to deform the projectile.

So, can pellets seal 800 psi by the use of the skirt?


Never tested it that high but it sealed to 350-400 psi in this project, the pressure would bend the projectiles a little but that's because they were only held by one pin, obiously having 2 or more would alleviate this problem.

is this gona be a new marker gun


Nope, one for the curio box

what do you use to make the tiny seals on the piston and at the end of the barrel, some type of rubber?


The piston is cut from solid 10mm thick rubber, so it doesn't need any extra seals. At the breech end of the barrel I wrapped some masking tape and covered it in Araladite to spread the contact area between the breech and the barrel and therefore avoid the barrel cutting into the piston.

Unread postPosted: Wed Jan 13, 2010 2:11 am
Author: grock
jackssmirkingrevenge wrote:
Sorry, I'm not convinced that a cartridge design is the most practical mechanism.


Fair enough, I'm aware this is mostly a personal obsession with flying brass hehe


I love brass too. It self lubricates. ;)

on your diagram, is grey a spacer and green epoxy?

Unread postPosted: Wed Jan 13, 2010 2:16 am
Author: jackssmirkingrevenge
grock wrote:I love brass too. It self lubricates ;)


By that logic you should love women too :P

on your diagram, is grey a spacer and green epoxy?


The grey is masking tape, cut into thin strips and wrapped around the barrel/schrader until it matched the inner diameter of the chamber. The green is Araldite epoxy, with small diameters even this "ordinary" epoxy is enough to cope with high pressures.

Unread postPosted: Wed Jan 13, 2010 12:43 pm
Author: spudkpi
The pressure in that little thing is unreal! I love it. I just want to say JSR, that I haven't really posted much on this forum but I have read quite a bit and you have a knack for this kind of thing haha. And I have an idea behind this mini gun. Say you make like 20 of these guns and had them placed in a spring magazine that fed into some sort of hammer chamber triggered by your finger. It would make it like a semi-auto or even full auto design. I just love how small this is! And one last thing, JSR what is that marker thing in the picture of your homemade fill station? I'm interested. :idea:

Unread postPosted: Wed Jan 13, 2010 12:57 pm
Author: jackssmirkingrevenge
spudkpi wrote:Say you make like 20 of these guns and had them placed in a spring magazine that fed into some sort of hammer chamber triggered by your finger. It would make it like a semi-auto or even full auto design.


Pretty much what I'm going for here ;)

what is that marker thing in the picture of your homemade fill station?


That's my recently resurrected pneumatic marker project built along similar lines to the subject of this thread.

Unread postPosted: Thu Jan 21, 2010 11:54 am
Author: clemsonguy1125
What pressure does it take to get it to fire because my mini wont fire at 80 psi.

Unread postPosted: Thu Jan 21, 2010 3:37 pm
Author: jackssmirkingrevenge
Mine works fine at 50 psi, but with such small chamber volumes and barrel lengths you really need much higher pressures to get decent power.