preloaded pneumatic cartridge

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
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jackssmirkingrevenge
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Sat Feb 09, 2019 5:44 am

Since I've been having a little fun with animations of late, here's a mechanically locked cartridge roughly to scale with a 3/8" projectile and a 1" outer diameter.

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hectmarr wrote:You have to make many weapons, because this field is long and short life
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hectmarr
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Sat Feb 09, 2019 8:34 am

Can you work with dieseling, for rather high operating pressures?
 
Ideas don't make holes. The weapons yes! ;)
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jackssmirkingrevenge
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Sat Feb 09, 2019 9:49 am

hectmarr wrote:Can you work with dieseling, for rather high operating pressures?
I'm not sure I understand, do you mean as a hybrid?
hectmarr wrote:You have to make many weapons, because this field is long and short life
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hectmarr
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Sat Feb 09, 2019 1:26 pm

no, I was referring to compression igniting a drop of lubricant, like the dieseling effect on normal spring-loaded compressed air guns :roll:
Ideas don't make holes. The weapons yes! ;)
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jackssmirkingrevenge
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Sat Feb 09, 2019 5:04 pm

hectmarr wrote:no, I was referring to compression igniting a drop of lubricant, like the dieseling effect on normal spring-loaded compressed air guns :roll:
Ah...

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That's a bit too much, even for me :mrgreen: :roll:
hectmarr wrote:You have to make many weapons, because this field is long and short life
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jackssmirkingrevenge
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Sun Feb 10, 2019 7:14 am

As part of my current animation spree, herewith a compendium of possible pneumatic air cartridge configurations:

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Exhaust valve with poppet valve pilot

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Balanced poppet main valve

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Balanced mechanically-locked pressure-actuated piston valve

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Balanced spool valve

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"Valveless" configuration with mechanically-locked projectile

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"Valveless" configuration with mechanically-locked projectile and unbalanced spool in order to counteract the friction from the locking balls being pressed against the sleeve by the projectile.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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jackssmirkingrevenge
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Wed Feb 13, 2019 9:47 am

Ball-locked designs drawn to scale:

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0.75" OD 3" long cartridge for a 3/8" (0.375") ball bearing projectile

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0.75" OD 3" long cartridge for a 3/8" (0.375") ball bearing projectile with spool piston to maximize internal volume

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1" OD 4" long cartridge for a 0.875" shot load
hectmarr wrote:You have to make many weapons, because this field is long and short life
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hectmarr
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Fri Feb 15, 2019 2:02 pm

You should write a book, digital or real. :bom:
Ideas don't make holes. The weapons yes! ;)
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jackssmirkingrevenge
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Sat Feb 16, 2019 7:38 am

hectmarr wrote:You should write a book, digital or real. :bom:
This is it ;)
hectmarr wrote:You have to make many weapons, because this field is long and short life
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hectmarr
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Sat Feb 16, 2019 7:52 am

Actually this forum is a book of collective authors.
Ideas don't make holes. The weapons yes! ;)
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jackssmirkingrevenge
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Sun Feb 17, 2019 3:34 pm

I finally did some work today on this cartridge malarkey and it worked out pretty well!

Here is a youtube video with some testing, even without a barrel it packs a punch...

[youtube][/youtube]

Very loud too, hearing protection was a must!

Here is the cartridge disassembled:

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Everything held up well except the firing pin that took a beating and started to jam, it's the reason the piston can be seen to pop out in the last two clips in the youtube video. Needs to be made out of steel rather than brass.

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My crude fill rig consisting of a probe that is placed in the mouth of the cartridge with the assembly then being clamped in a vice for filling. It took 9 pumps from my cheap-o chinese pump to reach 1500 psi.

Filling and firing cycle animated exactly as built, scale is in centimeters:

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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Sun Feb 17, 2019 5:53 pm

Very good! I like the cleanliness of construction and how it works. :bounce:
Do you plan to do others? I die to see him shoot with a barrel. :D
Ideas don't make holes. The weapons yes! ;)
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Sun Feb 17, 2019 8:36 pm

This prototype was to answer some questions I had about the design. I have verified that the filling system through the floating o-ring works, which removes the need for a separate filling valve. I also established that the force needed to actuate the mechanism is minimal, meaning only a weak firing pin on the launcher is needed and therefore it has a chance to eject the cartridge. I was also worried that the flow of high pressure air might blow out the o-ring on firing but this didn't happen.

Next step is certainly going to be a breech and barrel to establish ballistic performance and the potential to eject the cartridge.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Sun Feb 17, 2019 8:59 pm

Fantastic project Jack, and will be very interesting to see how it works with a barrel. Really like that style of triggering the cartridge and simplified filling. :-)
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Sun Feb 17, 2019 10:09 pm

jackssmirkingrevenge wrote:This prototype was to answer some questions I had about the design. I have verified that the filling system through the floating o-ring works, which removes the need for a separate filling valve. I also established that the force needed to actuate the mechanism is minimal, meaning only a weak firing pin on the launcher is needed and therefore it has a chance to eject the cartridge. I was also worried that the flow of high pressure air might blow out the o-ring on firing but this didn't happen.

Next step is certainly going to be a breech and barrel to establish ballistic performance and the potential to eject the cartridge.
Good plan that you have. Interesting data is what you got and what I see works wonders :)
High engineering, without doubts. I will be very attentive to the progress.
Ideas don't make holes. The weapons yes! ;)
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