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Semi-Auto Pneumatic Bolt

A place to ask general spud cannon related questions.
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How's my design?

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2
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All right
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Bad
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Total votes : 5
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Unread postAuthor: LikimysCrotchus5 » Sun Dec 16, 2007 6:53 pm

jackssmirkingrevenge wrote:I have no offspring that I know of (with the possible exception of a few sprogs somewhere in the Ukraine)


oh so you chose Ukrainian women!! Well let me tell you that they are a fine choice :)
But i have actually seen some of your offspring around, the tell me that they for some reason have a effieciency issue, that everything they have to do must be efficient and they tell me they get it from thier father, whom they dont know. And ofcourse they tell me this in Ukrainian. I just put it in english for your understanding purposes :) :)
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4SPC, My 4" piston 3" porting cannon
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Unread postAuthor: jackssmirkingrevenge » Mon Dec 17, 2007 1:57 am

Well let me tell you that they are a fine choice


Amen :)
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Unread postAuthor: al-xg » Tue Dec 18, 2007 4:52 am

The 3 port valve in normal position lets air into the front of the bolt.

It moves back, seals, the air leaks past the bolt and fills the chamber.

When the trigger is pressed, the 3port valve, blocks off the air inlet and dumps the air in front of the bolt.

The pressure in the chamber forces the bolt forward loading a paintball, and eventually goes down the barrel.

When the trigger is released, the exhaust port is closed off and the air inlet is connected back up to the front of the bolt.

I'll do a new drawing, just too many mistakes in the first one.

Edit: ok here it is.
Image
Did the same mistake...The launcher has just fired, the trigger is released and new air is on its way in. So the 3port push valve and the slide valve are both in initial position.

I've added a QEV on this drawing, it works just as the ones in paintball guns work.

The chamber is a little bigger and the bolt no longers moves all the way back, this is far from being an essential part in the design, it was just to show that the chamber volume could be made larger.

I added a few colours :roll: , Dark blue is the bolt, red is the barrel, light blue is the moving part of the 3-port valve, green is the QEV piston.

The thing on the side is a (bad drawing of a) slide valve, when the red sleeve is pulled back, air inlet is blocked off and top part of the pipe is vented.

Help this hopes... can't believe i actually wrote that :oops:
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Unread postAuthor: iknowmy3tables » Tue Dec 18, 2007 10:34 am

I'd have more trust in an acumilation chamber otherwise Its relying solely on flow from the inpup and you might as well use a blowgun
my design uses a 3way valve (the third being the exahust) for a acuator of the qev
like that in the legendary slider gun
http://www.spudfiles.com/forums/semi-auto-t160.html

@flash I doubt tubing creates better seals than orings, orings are the real deal its whats used on real commercial applications, seems to me like its just easier cause you don't have to bore groves
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Unread postAuthor: al-xg » Tue Dec 18, 2007 1:20 pm

In the last design ?
It works like any other piston valve, and as far as the use of the 3port valve, its exactly the same isn't it ? :?
Using the slide valve would make exactly the same as the Paintball Semi ... ?
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Unread postAuthor: F.E.A.R._Sniper » Thu Dec 20, 2007 5:16 pm

could you possibly use an electronic solenoid to make this work just like a paintball gun?

if you did that you could greatly increase the rof by throwing in some qev's on the noid and making an ultralite bolt. lmk what you think
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Unread postAuthor: Brian the brain » Thu Dec 20, 2007 5:39 pm

THis is actually exactly like THE ORIGINAL blow forward bolt!!!
Something we would call a COPY if we did not know people tend to find similar solutions to the same problem.Nice re-inventing there buddy...

Most of you are more familiar with the desendant wich is an inline version of this one.


I believe the original could be found on airpower.net, when that was still online...

I'm getting old...
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: al-xg » Thu Dec 20, 2007 7:21 pm

damn... oh well at least it works then? :wink:
What was wrong with this system ? It has less dead space, mmm but more pilot volume.
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Unread postAuthor: Flash » Thu Dec 20, 2007 9:54 pm

I redesigned it so it uses a barrel sealing valve to move the bolt forward and fire the paintball. The piston's exhaust is used to return the bolt to its original position.

Image

Image

The only problem that I can find with this design is that it would take slightly longer to fill the piston valve and move the bolt back after it has fired because the air gas to move through some tubing. It shouldn't be a problem with a higher pressure (25ish psi) though.

Brian the brain wrote:THis is actually exactly like THE ORIGINAL blow forward bolt!!!
Something we would call a COPY if we did not know people tend to find similar solutions to the same problem.Nice re-inventing there buddy...

Most of you are more familiar with the desendant wich is an inline version of this one.


I thought the original used a spring to return the bolt back to its original position. Although I'm not sure if the original is the one JSR linked to in his first semi auto thread or if its something else.

More later...
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Unread postAuthor: jackssmirkingrevenge » Fri Dec 21, 2007 12:16 am

I'm not sure if the original is the one JSR linked to in his first semi auto thread or if its something else.


this one?
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Unread postAuthor: Flash » Fri Dec 21, 2007 11:38 am

Oh sorry, I meant this one.

iknowmy3tables wrote:@flash I doubt tubing creates better seals than orings, orings are the real deal its whats used on real commercial applications, seems to me like its just easier cause you don't have to bore groves


I never said tubing creates a better seal than o-rings. :?

al-xg: I get it now. The bolt is used as a piston and the QEV vents the air in front of the bolt. And the 3 way valve is used to control flow to the bolt and actuate the QEV.

Brian the brain: What was wrong with the original blow forward bolt? What is the inline version of it?

F.E.A.R._Sniper wrote:could you possibly use an electronic solenoid to make this work just like a paintball gun?

if you did that you could greatly increase the rof by throwing in some qev's on the noid and making an ultralite bolt. lmk what you think


Was that directed to me or al-xg?
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Unread postAuthor: al-xg » Sat Dec 22, 2007 6:20 am

Yes, the QEV is only there as an optional way of accelerating opening times, like on paintball guns.
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Unread postAuthor: Flash » Sun Mar 09, 2008 6:33 pm

Just a quick update. I drew the bolt and air chamber in SketchUp. I also incorporated the floating o-ring design onto the bolt.

Image
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Unread postAuthor: iknowmy3tables » Sun Mar 09, 2008 9:46 pm

hey I really like the new floating oring does this mean you'll use a 3way valve to pilot this now

, recently I think I finally understand your intent with this design you are tying to make a sort of pilot operated valve in the bolt and your hoping that the use of pilot operation will get you the faster opening results like piston valves, well its a good idea but earleir I made a thread about this that there are similar designs people have been making however I'm very worried that the pilot in this system may not have surface area equal or greater that the area of the chamber, in other words the force of the pilot (which in this case is the area around the bolt) pressure must counter the force of the chamber pressure, the force of the air pressure as you know is the pressure (ex: psi pounds per in^2) multiplied by the area at which it applies (ex: in^2, squared inches) in this case it is the area on the bolt perpendicular to the direction of movement, since pressure is equal on both sides the area that the pilot applies must exceed the area that the chamber applies pressure to, and now that I think of it may not be possible
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Unread postAuthor: Flash » Mon Mar 10, 2008 11:42 pm

Yeah I'm going to use the three way valve design that al-xg came up with.

I was never counting on a pressure difference to move the bolt. If there was somehow, then it would just be an added bonus. I only intended to to use the pressure difference caused by the sudden drop in pressure by venting the space in front of the o-ring via the valve and QEV. Because of the floating o-ring, I don't have to worry about any air escaping past the o-ring and losing pressure that would be used to fire the paintball and move the bolt.

I did design a a bolt that would exploit surface area pressure for use in a semi-auto bb gun. the only drawback was that it had a rather excessive pilot volume. I'll post a design for it later.

Your explanation was perfectly understandable, in case you were wondering.
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