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Old 08-20-2015, 02:20 PM   #1 (permalink)
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Springless autococker valve.

Has anybody heard of or made an autococker valve where the stem fits into the body with some seals so that the input pressure is able to close the valve after being opened by the hammer? My brother mentioned the idea of recreating the valve to be springless so that after the valve is opened by the hammer, the resistance to air flow through it is able to close it. This may need to be on an actual autococker as opposed to pump to eliminate having the hammer resting on the valve stem.

A couple issues
The redesigned stem might not have enough dwell
It would need holes milled into it to let air pass through to the top tube, yet have enough resistance to flow for it to close after a shot.
Also it would probably not be able to close as well as traditional cocker valves when running low in the tank.

Just trying to start an open thread and get some ideas. Let me know!
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Old 08-20-2015, 03:29 PM   #2 (permalink)
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Such as and or.... But it would be inconvinient to remove. Take off guide rod etc.
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Old 08-20-2015, 04:41 PM   #3 (permalink)
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The concept is sound. A fill nipple has no spring and self-closes. Making it work in practice, not so sure. Interesting idea though.
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Old 08-20-2015, 05:24 PM   #4 (permalink)
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There's some good discussion about valve drag in the project leprechaun thread, if you can find it.

I think the biggest problem is that you can't have any (or much) main spring preload on the hammer. We usually just tighten up the ivg which increases the initial compressed tension, as well as the final position tension.

You need a main spring and hammer setup that limits the travel of the spring, even though you are adjusting the tension on it. Something like TJD's ICS might be converted to fit that.

You might be able to do the same thing more easily on an electro, since they just fling the hammer at the poppet and pull it back. Some of those valve springs just hold the poppet in place when there is no pressure.

***

On a mech, after the hammer contacts the poppet stem, the valve spring just becomes a counter spring to the main spring. It is a spring-mass-damper with a shift in spring constant and a forcing function that comes from the gas flow through the valve. I don't think getting rid of the valve spring will do as much as getting control of that valve face design (like the one drawn above) versus the total spring and hammer load. I'm talking about manipulating where the sweet spot is, not just finding it.
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Old 08-20-2015, 10:27 PM   #5 (permalink)
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It's an interesting thought but I'm wondering about the benefit. A spring is pretty simple and effective.

On your train of thought though, what about a pressure balanced cocker valve? Check out the one Simon did

Empire pressure balanced valve released today... - PbNation
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Old 08-21-2015, 09:50 AM   #6 (permalink)
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It's an interesting thought but I'm wondering about the benefit. A spring is pretty simple and effective.

On your train of thought though, what about a pressure balanced cocker valve? Check out the one Simon did

Empire pressure balanced valve released today... - PbNation
Man (MaD), those ads are obnoxious. Have you seen that valve since that post?

That brings up a point about any of these valve ideas; refinement needs to be aimed at a particular gas and marker setup. Simon was talking about getting rid of LPR variations on a pneumatic ram. Above, I'm talking about how poppet drag helps close the valve and helps compensate for pressure variations from CO2 and the HPR on a mech (sprung hammer at least). Any new design might have benefits in other setups, but it helps keep the discussion focused.

For instance on project leprechaun, they tried to limit the discussion to unregged 12g nelsons.
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Old 08-21-2015, 10:17 AM   #7 (permalink)
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I know that the empire pressure balance valves worked well when they worked, but they were testy in general, and I seem to recall at least one bushy balance valve crapping out because of the valve stem oscillating and grinding away at the valve face. It seems that valve springs act not only to close the valve, but as a guide to keep the valve pin aligned. With significant turbulence of air moving past the cup seal and pin, you'd most likely run into problems with that valve.

Now, your design looks like it would solve the oscillation problem. You're on to something.
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Old 08-21-2015, 11:03 AM   #8 (permalink)
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I know that the empire pressure balance valves worked well when they worked, but they were testy in general, and I seem to recall at least one bushy balance valve crapping out because of the valve stem oscillating and grinding away at the valve face. It seems that valve springs act not only to close the valve, but as a guide to keep the valve pin aligned. With significant turbulence of air moving past the cup seal and pin, you'd most likely run into problems with that valve.

Now, your design looks like it would solve the oscillation problem. You're on to something.

I figured start with delrin or something with well seated orings so that there's no metal on metal moving parts. Going to download student version of SW over the weekend.

Edit: personally, this item will be for a half block sniper that I like to run low pressure high flow.
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Old 08-21-2015, 01:44 PM   #9 (permalink)
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Are the lower tube dimensions of a 2k+ cocker pretty standardized? If anybody knows the diameter of the tube where the valve spring is, please let me know!

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Old 08-21-2015, 03:03 PM   #10 (permalink)
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Man (MaD), those ads are obnoxious. Have you seen that valve since that post?

That brings up a point about any of these valve ideas; refinement needs to be aimed at a particular gas and marker setup. Simon was talking about getting rid of LPR variations on a pneumatic ram. Above, I'm talking about how poppet drag helps close the valve and helps compensate for pressure variations from CO2 and the HPR on a mech (sprung hammer at least). Any new design might have benefits in other setups, but it helps keep the discussion focused.

For instance on project leprechaun, they tried to limit the discussion to unregged 12g nelsons.
I wasn't really directing that at you but as a more general reference. The design just reminded me of a pressure balanced valve. Simon's note here is interesting and I'll make the wild assumption that this conclusion was based on testing vs. just talking out of his rear... I know it wasn't the same design or intent but it's relevant I think...

"The valve on a poppet gun is closed by both the spring and air pressure. Springs (once broken in) are very consistent. The air pressure is no-where near as consistent in how it applies it's force."

Similar functionality to what the OP is looking for (really a self closing valve based on pressure) is in various other valve designs. I find the designs of piston valves pretty fascinating as well but haven't scratch built one. Still on my list..

Project Leprechaun was (is?) an interesting discussion. I think the main difference is that it had a specific intent which was to maximize 12g efficiency... or maybe more in general to really find the sweetspot of the nelson valve train and to figure what variations really make it tick. I'm more or less questioning the intent and benefit of a spring less cocker valve. I guess it's kind of a cart and horse thing so maybe the intent is to make it work and then see what the benefits are?

pancake, there's a CAD somewhere with the 2k specs. Some infos on the subject
https://www.mcarterbrown.com/forums/c...cad-files.html
autococker help

Yeah... I linked to that other site again. So shameful....

I do wonder about the machining quality and size of the area in front of the valve. It wasn't designed to have moving parts in there so I wonder what the surface is like in there and how well an o-ring will hold up.
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