Posted: 02/01/2010 14:28 PM Post subject: CO2 inflator pistol prototype
aspiring machinist
Joined: 15 Mar 2007 Posts: 18060 32518.54 Spud Bux
Following on from this discussion, I decided to see if I could make a simple pistol that could fire semi-automatically or in short bursts, as simply as possible powered bu a CO2 inflator. Here's the result of my efforts, not pretty but it was just a concept. The "chamber" is a 12 gram CO2 capsule adapted for HPA
This the basic breech construction:
The idea is that the chamber would be pressurised until enough pressure built up to "pop" the BB through the seal. Tested with a shock pump, BBs were popping at around 200 psi. The theory for semi auto is that light pressure on the trigger would give a low enough flow to pop just one BB, allowing single shots to be fired.
This didn't work out in practice, due to the way the inflator is constructed. The valve seems to be built in such a way that it's only sealed from allowing air to escape to the outside when it's fully depressed, meaning that gentle pressure on the trigger only caused air to leak from the valve without building enough pressure in the chamber. Pulling the trigger hard inevitably resulted in a full auto burst, cool but not what I wanted.
In conclusion, one for the failboat, but here, have a 12 round magazine dump at 1000 frames per second Target is a pellet tin lid, not the easiest thing to penetrate so I'm not surprised most of the shots ricocheted.
Joined: 15 Mar 2007 Posts: 18060 32518.54 Spud Bux
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hmmm... so the bbs and the piece of tubing didn't provide sealing on their own?
On the contrary, they seal perfectly. Here's a single shot pop-off test with the breech attached to my shock pump. Note that there's no mechanical detent, just a piece of silicone tubing of the type used in aquariums. The pump gauge reads to 400 psi and it pops around half way through. Not sure what's up with the audio by the way, my "tripod" was basically strapping the camera to my track pump with a rubber band, it might have been rubbing against the mike.
I don't as it is, it's only good as a burst fire pistol, and if that's what you want my piston valved BBMG was a lot more powerful using less than half the pressure.
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I like how the bendy barrel fits the style of your failparade
Prototype, it's a PROTOTYPE!!!
Gah.
Maybe I should make a diamond cross section barrel and have a Viagra MG
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Can't you put a needle valve in there to restrict flow?
The point is that the inflator valve leaks to the atmosphere when pressed, so it's not a matter of flow, it's a matter of the air not going where it's supposed to! For once the problem is with a purchased item, not my construction
Joined: 15 Mar 2007 Posts: 18060 32518.54 Spud Bux
POLAND_SPUD wrote:
even a blowgun should work just fine
Not quite, 110 psi pressure from compressor blowgun < ~200 psi pop-off pressure... Besides, the point of this was to make a high pressure pistol using a CO2 inflator anyone could buy cheaply, turns out it's not up to the job and I can't think of a way to modify it easily.
Joined: 15 Mar 2007 Posts: 18060 32518.54 Spud Bux
Fair point. Maybe I could even combine it with a clear chamber and barrel, hmmm.
Back to the subject of this thread, here's a(n excuse to use macro ) view of the CO2 inflator valve, the pin I'm holding in my worn out, epoxy encrusted fingers pushes down on what appears to be a simple spring ball valve and fits in the housing under the trigger lever. The white seal closes against the base of the housing buy the trigger has to be fully depressed for this to happen, which provides too much flow for single shots.
Joined: 15 Mar 2007 Posts: 18060 32518.54 Spud Bux
That might just have worked, unfortunately, true to form, I broke it...
Since it was popping at 200 psi with 4.4mm steel BBs, I decided to give it a go with 4.5mm lead BBs. 400 psi and still no pop, in the process of hammering it out I tore the seal and now it's leaking
Great work , not the desired result but at least I didnt have to try make and test this design myself , there must be a way I can make a co2 powered Semi Auto pistol though!?. Starting to look like It'll have to be a small hammer valve and adapt it so the co2 bulbs screw into it somehow? I dont think I could make a hammer valve small enough to conceal in a pistol sized frame though, plus it wont be semi auto with a hammer valve either.
Joined: 15 Mar 2007 Posts: 18060 32518.54 Spud Bux
I had tried to make a small auto hammer valve using a schrader here, rate of fire was too high and it wouldn't be much good for 0.177" either.
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it wont be semi auto with a hammer valve either
It will if you have a double action trigger. Can you get a revolver cap gun? If so you could conceivably cut it up and have it hammering on the inflator stem (the part under the trigger that I'm holding above), that will give you a burst of gas per trigger pull that would work great with a tee magazine. It would probably not be that pretty, but it would work
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Target is a pellet tin lid, not the easiest thing to penetrate so I'm not surprised most of the shots ricocheted.
as it is, it's only good as a burst fire pistol, and if that's what you want my piston valved BBMG was a lot more powerful using less than half the pressure.
, there must be a way I can make a co2 powered Semi Auto pistol though!?. Starting to look like It'll have to be a small hammer valve and adapt it so the co2 bulbs screw into it somehow? I dont think I could make a hammer valve small enough to conceal in a pistol sized frame though, plus it wont be semi auto with a hammer valve either.