Experimental Copper Piston Cannon

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.
SpudBlaster15
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Mon Dec 21, 2009 2:01 am

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Last edited by SpudBlaster15 on Wed Jul 14, 2021 7:28 pm, edited 2 times in total.
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boyntonstu
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Mon Dec 21, 2009 7:27 am

Nice design.

How far back does the piston travel?

How much air do you fell at the pilot exit?

Have you chronyed any shots?
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psycix
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Mon Dec 21, 2009 9:23 am

The piston is designed to completely seal off the pilot chamber during nearly the entirety of its travel.
During nearly the entirety of the travel, but certainly not during the entirety of the time!
I'd like to point out that there is quite some time between the pilot venting and the initial movement of the piston.
Especially pistons with a large porting compared to their diameter (faster opening!) will sit in that spot for a long time before popping open.


I think it performs better to make the floating O-ring act as a check valve by simply drilling a hole next to the groove.
Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

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jrrdw
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Mon Dec 21, 2009 9:31 am

Wow 10 fittings with in 1 foot :shock: ! Was that a soldering nightmare? You should get some video up.
SpudBlaster15
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Mon Dec 21, 2009 3:17 pm

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras nec placerat erat. Vivamus dapibus egestas nunc, at eleifend neque. Suspendisse potenti. Sed dictum lacus eu nisl pretium vehicula. Ut faucibus hendrerit nisi. Integer ultricies orci eu ultrices malesuada. Fusce id mauris risus. Suspendisse finibus ligula et nisl rutrum efficitur. Vestibulum posuere erat pellentesque ornare venenatis. Integer commodo fermentum tortor in pharetra. Proin scelerisque consectetur posuere. Vestibulum molestie augue ac nibh feugiat scelerisque. Sed aliquet a nunc in mattis.
Last edited by SpudBlaster15 on Wed Jul 14, 2021 7:28 pm, edited 1 time in total.
Nwest82
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Mon Dec 21, 2009 5:17 pm

Cool, so is this a "QEV" style firing valve? I think "QEV" is what the valve is called? when All the air is dumped from the chamber for the one shot and then the chamber must be refiled before the next shot can be fired?. I take it this design is a muzzle-loader and not breech loader? I working on a project, talked about below, but first I want to build a pistol like this in .25cal or .38cal, depends on power output.
I just joined spudfiles.com as I am working on designing a .50cal rifle using the "Hybrid combustion" design,( I think that is what they are called)? They use propane or MAPP gas, a fan which usually runs all the time, (while in the gun is in use/being fired), and burst discs, etc. I still need to learn what MAPP gas is and how available it is, as well as what the "burst-discs" actually do are for. So far from about 10min. of reading I came up with that idea that the "Burst-discs" are simple ball valves which are somehow pe-charged with gas then they are opened up to release the gas into the chamber as a way to control how much gas goes into the "chamber" so a person doesnt overdo it and blow the chamber up. like it could if the gas were to be bleed direct from the tank to the chamber. Also instead of burst discs, I'm thinking on a using small pump design with 2-hoses with some type of check valves inside, instead of the "burst-discs" so when pumped it draws in without pulling air from the chamber, then when you push it forces the gas into the chamber but not back into the bottle, I'm thinking simple ball and spring valves one the opens under vacuum, and closes under pressure, (the one that will come from the bottle). Then the other check valve will be the same thing but installed into the line in a reverse order so it opens under pressure, but closes under vacuum.
I am a Airgun/powderburing pistol/rifle, wtc builder, but have yet to deal with "Combustion" Gun designs and what to lean more as I can see these being able to throw a .50cal at high FPS, mabey even past the sound barrier ;)
Anyway time to do some more studying.

Nathan
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drac
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Mon Dec 21, 2009 7:37 pm

No offense man, but you need to do a lot more research on hybrids. Not trying to be a jackass or anything, but you have basically no understanding of them except for part names, and that's not enough to build one. Your enthusiasm is great, but I would hate to see you get hurt.
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Mr.Sandman
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Mon Dec 21, 2009 8:00 pm

Uhh Nwest82, I suggest you look at the wiki becaue im sorry but you have no idea what you are talking about. A hybrid is basically a combustion made of a stronger material that uses mixes a certain multiplication of an atmospheric mix whixh is used in basic spudguns. A burst disk is just that, a disk that is used to hold pressure back until it is too high and literally the disk bursts, allowing the projectile to be fired. Once again take a look at the wiki and if you have any questions pm me or another member.
Yeah, it's that important.
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jrrdw
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Mon Dec 21, 2009 8:21 pm

That's enough thread jacking, keep it on topic.
Nwest82
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Tue Dec 22, 2009 8:26 am

Sorry, I'll start my own thread as king questions then another when I do the build.
MR. Sandman: Thats why I stated that I have to do more studying, thinks for the tip. What I stated above was just what I gathered from 10min's of reading, I knew I was not "on-point", so to speak. I know about airguns and powderburners, I gunsmith and build both. But when it comes to spud guns its a whole different breed to me. I just remember watching a vidoe where a person opend up 3 "burst disc" then fired, I thought it was a way to bleed the gas into the chamber, but having a disc the "bursts" under pressure, (if pressure gets too high), makes more sense. Ok, well enough thread Jacking, Sorry", and thanks for the tip Sandman.
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