Slide valve automatic airgun

Building or modifying BB, Airsoft, and Pellet type of guns. Show off your custom designs, find tips and other discussion. Target practice only!
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Antonio
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Tue Jan 22, 2008 3:55 pm

Update: At the moment I am working on this idea using the same design as this airgun!!

This design was taken from fred's gun. I cant find the pictures anymore, I dont know where they went.
I came to work on this idea as I noticed that my inline valves were harder to convert to an auto. As the energy needed to open the valve is pretty large due to the high pressure behind the valve there is a narow pressure region for the gun to recycle by itself. My inline system has a hammer which has about the same surface area that of the valve; this also makes this region or margin smaller.

I did some calulations and found out that if the slanted edge of the new hammer is at about 6 degrees the force that the hammer spring exerts on the valve is about 10x. This means that my margin will expand and there will be more room for error.

This type of valve is also used on the Indain Creek paintball guns like the bobcat , alley/tundercat and the puma.

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I hope this design will give me a simple automatic bb airgun.
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[The extension swf has been deactivated and can no longer be displayed.]

Animation I made in interactive physics
Animation I made in interactive physics
Bolt , bolt spring and copper pipping
Bolt , bolt spring and copper pipping
Tapered bolt
Tapered bolt
You can c the valve pin Sticking out here!
You can c the valve pin Sticking out here!
Valve and valve spring
Valve and valve spring
Last edited by Antonio on Mon Jan 28, 2008 9:09 am, edited 9 times in total.
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pizlo
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Tue Jan 22, 2008 6:27 pm

Looks to me like it would work, just gotta get those springs right.
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ALIHISGREAT
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Tue Jan 22, 2008 6:29 pm

thats a cool design, i really must make myself some kind of semi-auto pellet/bb gun at some point :)
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daberno123
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Tue Jan 22, 2008 6:38 pm

The springs will be a pain to get right

Also what is pushing forward the hammer forward? Are you filling from behind it or from the chamber?

Looks like a simple design, I like it
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experament-u2
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Tue Jan 22, 2008 8:15 pm

looks good, are you planing to trigger the hammer with a sear or the sort?
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jackssmirkingrevenge
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Tue Jan 22, 2008 10:55 pm

The configuration looks a bit awkward but in theory it should work, and it suits your construction techniques so good luck :)
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Tom
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Wed Jan 23, 2008 11:04 am

Looks very simple I like it alot, only from what material ere you going to make the hammer?
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Antonio
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Wed Jan 23, 2008 12:41 pm

Tom wrote:Looks very simple I like it alot, only from what material ere you going to make the hammer?
Tom
I think from steel as aluminium would be too soft and would dent by the pressure of the valve stem. This could be a problem though.
jackssmirkingrevenge wrote:The configuration looks a bit awkward but in theory it should work, and it suits your construction techniques so good luck :)


Yeah thats why I thought of making this. Thnx!
experament-u2 wrote:looks good, are you planing to trigger the hammer with a sear or the sort?
daberno123 wrote:The springs will be a pain to get right

Also what is pushing forward the hammer forward? Are you filling from behind it or from the chamber?

Looks like a simple design, I like it
pizlo wrote:Looks to me like it would work, just gotta get those springs right.
True but as I said the margin for error is bigger in this case as the valve give me so much backpressure to recock. Behind the hammer is a spring, I left that out on the animation for simplicity. My airreservoir is attached to the valve tube like in other airguns I made.

Yeah I just left that out on the animation to keep it as simple as possible. It will look like the spyder and tippmann sear and trigger setup.
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Gippeto
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Thu Jan 24, 2008 2:57 pm

Hmm... Just a suggestion, but what about doing away with the taper all together, and using a tilting valve? If I'm thinking this through correctly, the valve would open/close faster. With a stepped bolt, it should also cycle on less gas volume. Have to limit bolt travel of course.

Other than that it is decidedly simple, which I like. Might have to put an airsoft SMG on the to-do list.
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Antonio
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Fri Jan 25, 2008 4:49 pm

Gippeto wrote:Hmm... Just a suggestion, but what about doing away with the taper all together, and using a tilting valve? If I'm thinking this through correctly, the valve would open/close faster. With a stepped bolt, it should also cycle on less gas volume. Have to limit bolt travel of course.

Other than that it is decidedly simple, which I like. Might have to put an airsoft SMG on the to-do list.
Hey I thought this over and the tilted valve might work as I still dont c what the benifits are over it as its harder to place. Btw what do u mean by a stepped bolt? I made these animations to give us some help. Can anybody give me their oppinion about the slanted valve?
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Slanted and normal valve placement. As you can c the bottom has more displacement so it needs less force to open the same valve. I think in this case its a factor of 70% (slope 45degrees)
Slanted and normal valve placement. As you can c the bottom has more displacement so it needs less force to open the same valve. I think in this case its a factor of 70% (slope 45degrees)
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Gippeto
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Fri Jan 25, 2008 6:41 pm

Hey, sorry for causing confusion. :oops: What I meant by a stepped bolt was that it changed diameter abruptly, instead of tapering. My thinking was that it would take up more volume and reduce dead space.

I should also have written tilting "face" valve. The valve would still be 90 degrees to the bolt, as you initially drew it. However the larger diameter (step) of the bolt would strike the valve stem and force it in the direction of travel, "tilting" the face of the valve off of the seat. The valve would have to be mounted on a spring such that it is brought back to a centered position when the bolt returns to a "cocked" position.
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Antonio
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Sat Jan 26, 2008 5:20 pm

I made this new prototype this evening but it doesnt work that well as though the parts look very good. It took me about 2 hours to combine it all. My problem now is that the valve tends to stay open after it has been hit. I have seen that it is able to cycle automatic but sometimes the bolt would just shoot too far and would leave the valve open. Another problem is the path way for the air from the valve to the bolt tube. The bolt blocks the flow and I made some holes in the side of the copper bolt guide, I guess these could have been bigger. As I soldered the valve pipe to the bolt guide already its ganna be impossible to change the sizes of those holes as my drills are too short. Does anybody have a solution for my partly working prototype? Image
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ghostman01
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Wed Mar 05, 2008 12:50 am

so is it working yet or is it still prototyping and have you made a video of it yet?
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Antonio
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Wed Mar 05, 2008 10:00 am

ajdevi92 wrote:so is it working yet or is it still prototyping and have you made a video of it yet?
I tried it out, but I havent made a movie as the result wasnt satisfying. As you can c on the pics I made the aluminium hammer I made tends to get dents on the slanted part. This makes it jam. So if I could make that part from steel it might work better. >The system does work just that I dont have the right materials :(
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ghostman01
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Thu Mar 06, 2008 4:46 am

ok yeah ive been trying to design a semi pistol as you can probably tell from my ideas lol, if you can try and find a internal picture or animation of the daisy 15xt it would much appreciated because i cant seem to find any


um how does the air get to the barrel doe sit just go past the bolt or is there a hole
Last edited by ghostman01 on Sun Mar 09, 2008 9:49 pm, edited 1 time in total.
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