Semiauto design; piston/hammer valve type

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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Fri Mar 07, 2008 8:55 am

This design is actually automatic, but as it will cycle too fast then I am ganna add a mirrored tippmann or spyder like trigger and sear. This setup is also very good as not that many parts are moving. I am not sure if someone thought of this before, probably they did. But yeah this gif visualizes it pretty good. With the materials I used on previous projects I am able to make this system''. Btw dont doubt if the airgun will actually cycle; it will. I did calculations on that and know exactly which springs to use etc.

Plz leave feedback or comments.
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a gif with no color
a gif with no color
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The blue is the air
The blue is the air
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Jared Haehnel
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Fri Mar 07, 2008 9:09 am

The action looks good to me...It should cycle just fine 8)
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jackssmirkingrevenge
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Fri Mar 07, 2008 9:10 am

ant wrote:I am not sure if someone thought of this before, probably they did.
It's basically the same idea I proposed here, though I wasn't the first to come up with it.

Image

The one issue I see with your diagram is that the poppet valve seat is far too big in comparison to the barrel diameter and will require a considerable amount of force to open disproportionate to the flow advantage.

I'm making something similar (though popping off instead of hammer actuated) I'll post pics of my progress when I get home :)
hectmarr wrote:You have to make many weapons, because this field is long and short life
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bigbob12345
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Fri Mar 07, 2008 9:13 am

good idea it should work well but the only problem that comes to mind is power which would suffer with such low volume if it wasnt high pressure.
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jackssmirkingrevenge
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Fri Mar 07, 2008 9:22 am

How were you planning on cocking the bolt?
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Antonio
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Fri Mar 07, 2008 9:27 am

jackssmirkingrevenge wrote:
ant wrote:I am not sure if someone thought of this before, probably they did.
It's basically the same idea I proposed here, though I wasn't the first to come up with it.

The one issue I see with your diagram is that the poppet valve seat is far too big in comparison to the barrel diameter and will require a considerable amount of force to open disproportionate to the flow advantage.

I'm making something similar (though popping off instead of hammer actuated) I'll post pics of my progress when I get home :)
I was sure I wasnt the first here. Yeah the valve area may be a problem. But I made this simulation using excel and now I can fill in the area of the valve and of the hammer'' and find the optimum spring k costants that I need for it to cycle in a range of 8-1atm of pressure> its pretty cool. Its kinda hard to figure out the dwell time though as it doesnt open once but about 12 times within 0.2 seconds for my type of airguns. Plz make some pics> I am really curious!!
bigbob12345 wrote:good idea it should work well but the only problem that comes to mind is power which would suffer with such low volume if it wasnt high pressure.
Yeah true. Thats what you have to give in. Not sure how much it will decrease the speed of the bb though:S Hopefully not that much that it becomes half the original speed for this type of valve but then manual.
jackssmirkingrevenge wrote:How were you planning on cocking the bolt?
Thats a good one. I am first ganna try to make this setup without trigger or ball feed''. So I will make one where the hammer tube sticks out so that u can pull it/cocking it with ur fingers. As my design now is pretty small scale I dont have too much space for such things, so thats why I thought about making a prototype which cant shoot first.
Last edited by Antonio on Fri Mar 07, 2008 9:33 am, edited 2 times in total.
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Jared Haehnel
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Fri Mar 07, 2008 9:29 am

Jack I like that design its very simple, very few moving parts...the work of a genius...
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Antonio
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Fri Mar 07, 2008 9:34 am

Jared Haehnel wrote:Funny I had just thought of that too... Jack I like that design its very simple very few moving parts...the work of a genius...
The problem is, making it work in real life lol. But yeah this one should be doable.
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jackssmirkingrevenge
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Fri Mar 07, 2008 9:51 am

Jared Haehnel wrote:the work of a genius...
A genius would have only one moving part - the projectile ;)

I had though of a way of using a conceptually similar system but allowing it to cock here but again it's similar to some paintball markers:

Image
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Antonio
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Fri Mar 07, 2008 10:06 am

jackssmirkingrevenge wrote:
Jared Haehnel wrote:the work of a genius...
A genius would have only one moving part - the projectile ;)

I had though of a way of using a conceptually similar system but allowing it to cock here but again it's similar to some paintball markers:
I was thinking of this:
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The red dots are hinges. So when the hammer moves back the upper tube that slides in the barrel moves forwards and seals the load port. In that tube there is a hole to port through the air.
The red dots are hinges. So when the hammer moves back the upper tube that slides in the barrel moves forwards and seals the load port. In that tube there is a hole to port through the air.
hammerauto_389.gif (5.88 KiB) Viewed 6176 times
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Jared Haehnel
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Fri Mar 07, 2008 11:01 am

Ok, so its the work of a pseudo genius, anyway it looks like there are many ways to skin this cat... do you suppose you could modify a junk paint ball gun to fire bb's... you would get around the need for a machinist...maybe
My current projects....

Currently buying part for...
http://www.spudfiles.com/forums/my-new- ... rt,15.html
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C02 tank hybrid
Screen doors for submarines...
Hawkeye
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Fri Mar 07, 2008 11:23 am

There is a modified paintball gun at Airsoft Innovations(or Innovative Airsoft?) that shoots plastic bb's.
Very touchy weapon and downright dangerous. The guy considered it a failure. Inconsistent etc. He mentioned having it spit out brass somehow as well. I'm surprised Jack didn't come across this.
I'll try to find the link to it.
We also discussed a bb-gun that was made from various store parts and homemade tweaks from the BB machinegun forum. It was based on a paintball valve with an airsoft modified mag to hold bb's.
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Antonio
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Fri Mar 07, 2008 12:52 pm

Hawkeye wrote:There is a modified paintball gun at Airsoft Innovations(or Innovative Airsoft?) that shoots plastic bb's.
Very touchy weapon and downright dangerous. The guy considered it a failure. Inconsistent etc. He mentioned having it spit out brass somehow as well. I'm surprised Jack didn't come across this.
I'll try to find the link to it.
We also discussed a bb-gun that was made from various store parts and homemade tweaks from the BB machinegun forum. It was based on a paintball valve with an airsoft modified mag to hold bb's.
Sounds really inspiring.. well atleast the last one lol. Would be great if you could find some pics or links to these topics/projects!
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jackssmirkingrevenge
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Fri Mar 07, 2008 1:03 pm

Hawkeye wrote:I'm surprised Jack didn't come across this.
I'm not that easily excited :P

Do you mean these?

They also have a barrel conversion that allows it to be chambered for 0.177 BBs

Image

[youtube][/youtube]

They're available locally, I'm tempted to buy one, but not just yet.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Jared Haehnel
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Fri Mar 07, 2008 1:19 pm

The movie doesn't quite play but its a sweet looking gun...
My current projects....

Currently buying part for...
http://www.spudfiles.com/forums/my-new- ... rt,15.html
Still on the drawing board...
C02 tank hybrid
Screen doors for submarines...
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