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semi auto pump action

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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semi auto pump action

Unread postAuthor: trollhameran » Tue Jan 08, 2008 1:25 pm

today me and a friend of mine came up with an idea for a semi auto pump action gun, the numbers on the picture correspond with the numbers in the explanation.

Image

1. The barrel, has a hole on the top near the valve where the ammo will be loaded, and a rubber seal each side of the hole (blue strips)

2. the hopper, will fit on to number 6, holds the ammo.

3. valve, drawn as a ball valve but could be any sort of valve.

4. Sleeve, used for the pump action, has a hole which the hopper fits over, fits snuggle over barrel and when pulled back the hole in it and the hole in the barrel line up allowing ammo to fall into barrel.

5. Ball valve, connected to number 4 so that when 4 is pulled back it opens the valve to allow air into the chamber then when 4 is pushed forward again it closes valve to stop air getting out.

6. rubber sleeves, stop air from leaking out between 1 and 4 when gun is fired.


If anybody has any questions about how it works, or has any suggestions on how to improve the design they would be greatly appreciated as i plan to build the gun if there are no flaws in the design.
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Unread postAuthor: jackssmirkingrevenge » Tue Jan 08, 2008 1:44 pm

looks like it would work, though it won't be pretty :)

[pedant]Strictly speaking, a semi-automatic action is one that fires once for every pull of the trigger, without needing to be externally cycled, so a "pump action semi-auto" is a contradiction in terms.[/pedant]
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Unread postAuthor: POLAND_SPUD » Tue Jan 08, 2008 1:46 pm

well it is not exactly a real semiauto.... it is a pump action... u use your muscles to load next round...

but your general concept is ok - you could get quite high ROF... about 1shot/ 2 seconds is possible with this

If I were you i would make this an overunder gun and connect the valve no 5 with the sleeve in some nicer/ less ghetto way....
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Unread postAuthor: trollhameran » Tue Jan 08, 2008 2:29 pm

I was thinking of having a co2 canister attached under the valve number 5, which would constantly be on so that when the sleeve is pulled back and the valve opens, the chamber will be filled ready for the next shot.

My friend originally thought of having a small motor with a wheel on it and a rod which would connect to the sleeve like a cam which would be used instead of it being pump action, and then have some way of firing it as an auto without having a constant flow of air going threw the barrel.

I agree that it would look better with a neater way of attaching valve 5 to the sleeve, so ill have to try and think of a new way of doing that.
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Unread postAuthor: Hubb » Tue Jan 08, 2008 2:33 pm

Hooking up a CO2 canister to that will not be pretty either, which means, it will probably not perform like you wish. When you pull the valve open, you will waste a very significant amount of CO2.
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Unread postAuthor: trollhameran » Tue Jan 08, 2008 2:46 pm

Im not to bothered about it being really portable so i could probably just connect the compressor with a quick connect instead of having a co2 canister and then i can use it as a single shot if i need it to be more portable.
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Unread postAuthor: Hubb » Tue Jan 08, 2008 2:54 pm

An option in using CO2 would be to place a regulator on it. This will allow you to leave that valve open for as long as you want. Oh, and a little bit of custom work and imagination can make this a beautiful piece.
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Unread postAuthor: trollhameran » Tue Jan 08, 2008 3:14 pm

Using a regulator was what i was planning on doing, im not very familier with co2 though so i didnt realise that was what it was called untill i looked it up a minute ago. Are co2 tanks easy to get refilled because i just looked on a paintballing website and the co2 canisters are around £80-£100.
If i were to use a co2 tank with a regulator would i still need the ball valve on the end of the chamber? or would the regulator be enough?

Thanks for the help and kind words about the design hubb017

If i were to use a co2 tank with a regulator would i still need the ball valve on the end of the chamber?
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Last edited by trollhameran on Tue Jan 08, 2008 3:27 pm, edited 1 time in total.
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Unread postAuthor: iknowmy3tables » Tue Jan 08, 2008 3:27 pm

okay sure but its only pump action and ball valves which is old school for a lot of us

try a blowgun valve or something that might be easier to install on the slide, and remember if you try to upgrade to a sprinkler valve won't instantly close if the pressure increase (the filling of the chamber)

if your interested in high rof study bbmgs, but for pneumatics some basic designs that you should closely study are
http://www.spudfiles.com/forums/semi-auto-t160.html
http://www.spudfiles.com/forums/true-semi-t156.html
http://www.spudfiles.com/forums/full-au ... t4108.html
and possibly this
http://www.spudfiles.com/forums/gb-semi-t7899.html
but thats some of the advance stuff
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Unread postAuthor: POLAND_SPUD » Tue Jan 08, 2008 3:27 pm

trollhameran wrote:
I agree that it would look better with a neater way of attaching valve 5 to the sleeve, so ill have to try and think of a new way of doing that.


something like this would do...

ofcourse if you really want to you could use more advanced designs and valves... but I think that a ball valve is enough for this function...
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Unread postAuthor: trollhameran » Tue Jan 08, 2008 3:33 pm

@iknowmy3tables: i know that pump action and ball valves is old school for alot of you but i only started making cannons about a month ago and currently i have only made one, so im still in the process of learning about different types of valves and what not, and i am planning on using a different type of valve as the trigger system but i didnt no how to draw any other type.

@POLAND_SPUD: thanks for taking the time to edit the origianl design for me, your new version looks alot neater and looks as though it will be easier to build as well.
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Unread postAuthor: Hotwired » Tue Jan 08, 2008 4:39 pm

Umm... you might want to try hosting the specific picture somewhere.

All I'm seeing there thewarp is the path to your My Pictures folder. And your name :wink:
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i am the friend and my idea looks nuffin like that lmao

Unread postAuthor: thewarp16 » Tue Jan 08, 2008 4:54 pm

EDIT: thanks spudgunner i wuznt sure how to add pictures and yes that is my name lmao.

when you slide the sleeve back to the loading position a baintball will drop in through the hole in the barrel(the bluey bit).
as you slide the sleeve forwould into the firing position the loading hole in the barrel will be filled and made almost airtite.

as the C02 tanks line and the other hole in the barrel line up the air will go straight though and fire the painball out.


this thing will fire as fast as you can pump it lmao have fun making it i know i wont bother.
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Unread postAuthor: trollhameran » Thu Jan 10, 2008 12:27 pm

Image

i just came up with this idea for filling the chamber automatically, im not sure if itll work though because ive never done anything like it before.

the blue is air. the black block thing is like a piston. When the compressor or your air source is connected to the chamber it fills up and as the air goes through the holes in the piston and fills the chamber the pressure pushes the piston back and the narrow part on in slides into the narrow part of the chamber where the air source is connected and blocks off the air supply, then as soon as the gun is fired the pressure is released and the spring pushes the piston forward again and the air starts flowing back into the chamber.

Does anybody think this will work and does anyone have any ideas to improve it, or make it work if they think it wont. [/img]
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