First draft, pressure chamber and valve design ...........

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DoctorFrankengun
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First draft, pressure chamber and valve design ...........

#1 Post by DoctorFrankengun »

.......... for a homebuilt airgun. This first drawing shows the very basic idea that I have for the pressure chamber and valve. It doesn't show the seals. The seals and pump cup that I have are 1-1/2" diameter hydraulic components. I am hoping to get some speed out of 2 pumps :twisted:

Totaly experimental but should be lots of fun \:D/

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airsmith282
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#2 Post by airsmith282 »

very cool dude very cool
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sniper
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#3 Post by sniper »

Nice diagram & it's looking good, I can see it's happening already ....
jezX
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#4 Post by jezX »

i hate to be picky . but i have built many valves . the single hole on one side will not allow good air flow . and the slant on the pin that plugs the hole will prevent flow as well . when the hammer hits the pin it will turn the valve pin and the valve pin will get a spot indented from the exaust port being only on one side, this dent will allow leeks .
also having a pump 1.5 ''od, you will only get about 300psi unless you are superman with mechanical advantage . the surface area is to high to get good psi . if you could get a 1.5'' valve that would be awesome but the pump must be less then 1'' to get high psi .the smaller the pump the higher the psi possable
i don't want to discourage you but your idea will not work well . . if you would like some help i can give more info
RM422
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#5 Post by RM422 »

I think Jezx may have a point but I can already see what you are doing and can also see it working.
ONE SHOT, ONE KILL
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airsmith282
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#6 Post by airsmith282 »

hey guys me again here.. well i say to metalmuncher to go for it go with the design you made and if you do run into problems as sudjested by jez then at least you can improve on the model,,jez is a pretty cool guy and knows his stuff well..but i say to try it the way it is. you never know might just work out great with the present model design,,iam not a valve builder like jez ,but i have done some stuff that some people said that will never work and it did.. the one edge i rely on is i never look at logic and there is nothing that cant be done,and any idea is a wounderful idea.and if what you invent does not work or work well, its not to be looked at as a failer its to be look at as it needs some work.advise from thoes that have more experience,is always a good thing its part of how we learn,i have been smithing for over 2 years now and i have come along way and still continue with my mentor all the time and i ask alot of questions of others as well.. and i have come up with some really neat ideas as well,and have learned to expand on ideas as well, so all is good...
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#7 Post by webstien »

better to have tried and failed then to have never had tried at all! :lol:
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DoctorFrankengun
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#8 Post by DoctorFrankengun »

Thanks for the encouragement fellows :)

jezX,

You input is very welcome. The drawing lacks many details with regards to the valve. I will draw another and post it for your feedback.

I understand your point about the 1-1/2" pump. In the past I have worked with both air and hydraulic systems in a sawmill. The reason that I would like to try this is because I would like to get killing speed with 2 pumps. The 1-1/2" pump will compress a large volume of air on each stroke. I have no idea how much pressure I will be able to get (or how much I need) but I think that I will try just for litter's and giggles.

The pump lever will be hinged at the end of the tube (like a 1377) but will be much longer. It will extend under the trigger guard to the bottom of the grip. In total it will be from 20" to 24" long.

I have been doing some experiments with a break-barrel spring powered gun that I picked up at a yard sale. It has a 1" piston that travels about 2".
The exhaust port is in the center of the tube but goes up on an angle to meet the barrel bore. It is the same diameter as the barrel bore (177)

Am I wrong in assuming, that if I can pump twice the volume of air that this gun moves into the pressure chamber of my gun and let it escape instantly thru a hole the same size as the barrel bore when the trigger is pulled, that my gun will work? :?:

I wonder how much pressure a break-barrel actually makes? I am thinking that it relies more on moving a certain volume of air very quickly than pressure. :-k
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DoctorFrankengun
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#9 Post by DoctorFrankengun »

My CAD drawing skills are not the best but hopefully this one will make my idea a little more clear.

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Here are the seals that I intend to use................

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Voltar1
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#10 Post by Voltar1 »

Metal, figure out your levers and the mechanical advantage available, use the force you think you can muster multiplied by the mechanical advantage to get the force on the piston. Assuming 100%efficiency with that force applied to the piston area you will know what psi you can develop. To get your unit performing as in hot you will want 1500psi plus stored in your valve.
As to valve sealing a sharp edge will likely be what you want to achieve.
Good luck and thanks for keeping us posted!
Walter...
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jezX
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#11 Post by jezX »

if you like i will send you the best design posable . to achive the most power , if you do keep your design you may want to get teflon washers (or delin).i think the ones you have are rubber . the teflon work great and dont squish like rubber.
i wish i could post stuf on here ,i'm working on a new valve .it will work for qb78 style guns and get alot more power but i can't post .
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DoctorFrankengun
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#12 Post by DoctorFrankengun »

jezX wrote:if you like i will send you the best design posable . to achive the most power , if you do keep your design you may want to get teflon washers (or delin).i think the ones you have are rubber . the teflon work great and dont squish like rubber.
i wish i could post stuf on here ,i'm working on a new valve .it will work for qb78 style guns and get alot more power but i can't post .
Thanks for the kind offer. I would very much like to have your design =P~ .

I would be happy to post your stuff for you. Just let me know what you would like posted and what you would not.

metalmuncher49@gmail.com
jezX
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#13 Post by jezX »

i sent you a picture . i'll get a good one done today and send it to you . you can post it as well. if you wish
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