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2 valve metering vs hammer valve

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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2 valve metering vs hammer valve

Unread postAuthor: boyntonstu » Mon Nov 09, 2009 9:40 am

Is there any advantage/benefit of using a valved firing chamber behind the piston valve that is pressurized from a larger chamber instead of using a hammer valve for multiple shots?

Example here:

http://www.airgununiverse.net/community ... 135.0.html

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Unread postAuthor: qwerty » Mon Nov 09, 2009 11:00 am

Yes, i suppose there is. Using a sleeve valve to fill the gun and pilot it at the same time is a great way of making semi-auto guns but you need high pressure and a small chamber at for the QEV or piston valve.
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Unread postAuthor: Ragnarok » Mon Nov 09, 2009 11:13 am

In minimal words, easier regulation (and thus consistency).

While it is possible to build regulated hammer valves, they're not the simplest thing in the world.
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Unread postAuthor: inonickname » Tue Nov 10, 2009 7:17 am

There was a post very recently from someone showcasing a regulated hammer valve. Perhaps drop him a line.

In my opinion, and I have no idea why it isn't used in commercial airguns the two tank method is superior. Simply for the reason that it allows use of a faster valve with more flow, less restrictions and less turbulence. It's seen time over and over, we can obtain similar powers to commercial airguns with substantially lower pressures.

Commercial guns could definitely improve performance like this. There's plenty of more powerful valves than poppet/hammer valves out there.

Though a ball valve isn't the way to do it.
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Unread postAuthor: Ragnarok » Tue Nov 10, 2009 7:35 am

inonickname wrote:There was a post very recently from someone showcasing a regulated hammer valve. Perhaps drop him a line.

Oh, I'm familiar with how they work.

But given I've yet to see much (if any) building of home-made regulators, I can't see many here going to the trouble of a regulated valve.
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Unread postAuthor: boyntonstu » Tue Nov 10, 2009 8:53 am

Ragnarok wrote:
inonickname wrote:There was a post very recently from someone showcasing a regulated hammer valve. Perhaps drop him a line.

Oh, I'm familiar with how they work.

But given I've yet to see much (if any) building of home-made regulators, I can't see many here going to the trouble of a regulated valve.


if we could design a 2 valve system that is integrated with the breech open/close motion, we would be half way to a repeater.

(The next step would be magazine feed.)
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Unread postAuthor: Ragnarok » Tue Nov 10, 2009 9:05 am

boyntonstu wrote:if we could design a 2 valve system that is integrated with the breech open/close motion, we would be half way to a repeater

Talking of which, what's happened with the community projects?
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Unread postAuthor: boyntonstu » Tue Nov 10, 2009 9:12 am

Ragnarok wrote:
boyntonstu wrote:if we could design a 2 valve system that is integrated with the breech open/close motion, we would be half way to a repeater

Talking of which, what's happened with the community projects?


I dunno, wasn't a member then.

I try to share my ideas and ideas from other forums as best as i can.

How do we organize a community project?

BTW Here is a what if:

Each time we recharge the little chamber we add some volume by opening additional small cylinders similar to a revolver.

The extra volume may help keep the shots uniform in power.

edit; having rethought the above, this would be better;

A sliding/sealing piston that can be screwed into the already pressurized pre-chamber after each shot to compress the air up to a value that would produce the same power as the first shot.
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Unread postAuthor: Technician1002 » Tue Nov 10, 2009 12:33 pm

I second the consistancy of a small firing chamber. I've been playing with the Marshmallow cannon with it hooked directly up to a low pressure regulator with the large barrel with the loose sabot. Cycle times are short. I don't bother to shut off the air for a shot due to the flow rate of the hose. It's ready for the next shot as fast as I can drop in the next golf ball, marshmallow or other projectile. A shuttle slide tied to the trigger could make it full semi auto. Each pull discharges it and retrives a round from the hopper. Each push drops the round into the barrel and closes the valve. A rapid pumping motion will provide rapid fire.
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Unread postAuthor: POLAND_SPUD » Tue Nov 10, 2009 12:42 pm

Talking of which, what's happened with the community projects?
I think that people lost interest in it

the problem was that the final design was a compromise between different designs proposed by members... designs that they always wanted to build or dreamed of

but in the end there could be only one design... so no one was really interested in it

I think the idea was great but it won't work unless what I've mentioned earlier is taken into consideration
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Unread postAuthor: boyntonstu » Tue Nov 10, 2009 4:35 pm

Technician1002 wrote:I second the consistancy of a small firing chamber. I've been playing with the Marshmallow cannon with it hooked directly up to a low pressure regulator with the large barrel with the loose sabot. Cycle times are short. I don't bother to shut off the air for a shot due to the flow rate of the hose. It's ready for the next shot as fast as I can drop in the next golf ball, marshmallow or other projectile. A shuttle slide tied to the trigger could make it full semi auto. Each pull discharges it and retrives a round from the hopper. Each push drops the round into the barrel and closes the valve. A rapid pumping motion will provide rapid fire.


How about adding a pressure gauge and a shock pump to make every shot even?

A hybrid if you will.

A pressurized main chamber + a built in shock pump to add pressure to the small chamber.


if you are out in the field, the shock pump could do it all.
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Unread postAuthor: iknowmy3tables » Tue Nov 10, 2009 7:21 pm

hammer valves are a little more friendly than 2 part systems where one might accidentally open both valves and they allow for an actual finger trigger, but they are harder to make. 2 part systems are just easier to make, and since an extremely large hammer valve may be impossible to open 2 part systems are better for that

boyntonstu wrote:BTW Here is a what if:

Each time we recharge the little chamber we add some volume by opening additional small cylinders similar to a revolver.

The extra volume may help keep the shots uniform in power.

edit; having rethought the above, this would be better;

A sliding/sealing piston that can be screwed into the already pressurized pre-chamber after each shot to compress the air up to a value that would produce the same power as the first shot.


well you're adding another step to the process, and no one likes that, I'd just get bored and just leave it that the largest volume. I think regulating the input is the better way to go and the methods of doing that are,
1.use a regulator valve
2.use a gas from a liquid source ex: green gas/propane, butane
3.use air from a source with a volume under a fairy consistent mechanical compression ex: a thick rubber blatter, you can also use a piston driven by an high pressure air cylinder with a considerable about of expansion volume
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Unread postAuthor: D_Hall » Wed Nov 11, 2009 12:32 am

boyntonstu wrote:if we could design a 2 valve system that is integrated with the breech open/close motion, we would be half way to a repeater.


You don't even need to get that fancy.

One of the very first spud guns I ever saw ran unregulated CO2 in a 2 chamber set up. The first chamber was (obviously) a normal CO2 tank (paintball tank in this case). From there, the gas went through a needle valve to fill a second small chamber that was used for firing.

The second valve was your typical pilot-actuated piston valve. Nothing particularly exotic other than the fact that it ran unregulated CO2.

The set up was such that it took about a second to fill the "shoot chamber." If you simply held down the trigger? Yeah, you'd just lose all your gas. But really, 1 second is a very long time for such things.

So you pull the trigger, it dumps the shoot valve and a very small amount of gas is lost from the main chamber. You let off the trigger, the piston resets (chamber was filled from the pilot-side), and 1ish seconds later the gun was ready to fire again.

Note that the gun was a single shot breech loader. It took more than 1 second to load a new projectile. I always thought that was a safety issue, but even it wouldn't be that hard to work around.
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Unread postAuthor: iknowmy3tables » Wed Nov 11, 2009 1:41 pm

yes D_hall is right, having two valve is unessesary, having to operate two valves is something you find in a newbie gun, to use a working piston valve with a permanently attached input you either need to have a very limited rate of flow, you can add a valve to cut it off but then you have to play around with that too when your shooting. the other approach that uses piston valves which I would say is the best approach is to use a 3way 2position valve as a pilot
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