clide's take on semi-auto (now with animation)

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Postby nitz7978 » Tue Sep 21, 2004 8:26 am

after watching that vid, i must change my pants.... i must build one :) very nice man. many cudos.
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Postby Melkor » Tue Sep 21, 2004 11:14 am

The clever part of this design is the way that the air input shuts when you pull the trigger. You can alter the piston mechanism itself, but this is the important thing that enables the gun to be semi-auto. Great innovation, clide. Way to go!
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Postby iMacThere4iAm » Tue Sep 21, 2004 11:44 am

on the subject of video codecs I prefer Sorenson 3 for top compression and quality, but most people don't have it. If you are using QuickTime (I guess you are) then any other one from the list should work. I think it gives you a preview and an estimate of the file size doesn't it?
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Postby clide » Tue Sep 21, 2004 1:45 pm

Countz, I know what you mean. I have another semi-auto design that was WAY overengineered. It had several problems, but I think I could get it working, just haven't decided if i want to yet, this is so much easier and saves alot of space compaired to my other design.
There are seams in there, they are just hard to see. The tee has a female adaptor on the front and back and the elbow also has a female adaptor on it. The wrench grips on the adaptors were lathed off to give them a nice smooth look, and since I can get torque with the body of the tee I don't need them.

Melkor, sounds like you got it down. This type of exhaust/fill could be added to just about any piston valve to make it semi-auto, just the ROF might not be high without modifying the piston.
Edit, and a fast loading system of course

iMac, I use Adobe Premeire and it just lists all the video codecs I have installed, and I can't remember which ones I have installed and which ones I already had. So I'm not sure which are common.
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Postby IzzyDoesIt » Tue Sep 21, 2004 9:46 pm

OOOOOH Yeah! Pretty awesome semi! I like the way you prevent air waste. That is a pretty fast rate of fire! I like it a lot! The avi says it all, it is hot!

Too much stuff to digest... Will look at it closer later.
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Postby Aaron » Tue Sep 21, 2004 10:36 pm

Clide, amazing work. The slider valve is a great design for a combo fill/exhaust valve. I have a question though, were you unable to use the McMaster slider valve for some reason like low airflow or did it only work one way?

Also it's nice to see that the forward working piston breech loading design actually works. I always thought the air would just blow through the smaller pipe without ramming forward.

Now... I must upsize your design to fit a 5' golfball barrel.....
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Postby clide » Tue Sep 21, 2004 11:53 pm

Thanks again, If it wasn't for all you ol'timers I wouldn't have ever been able to build something like this. Just about everything I know about spudguns came from this forum. :)

Aaron: I didn't use the slide valve because it was so pretty :oops: I would have had to drill into it to mount springs and and I didn't want to screw up the valve. It also had features that I didn't need, like a sleeve to redirect exhaust air flow and a 1/2" input hole, so I would to have to use a bushing to get down to 1/4". So the it would end extra length to the back of the gun which I didn't want. It also seemed to only have one o-ring on the front of the sleeve, so if you pushed the valve back slowly there was a point where it would be exhausting the input air. On top of all that, it is just more impressive/satisfying to build my own.8) I also already had all the materials onhand from other projects, so it cost me nothing over what I had already spent.
On the breech loading you may want to look at the diagram again. Notice that the bolt is capped at the back and it slides into a close fitting pipe, so it must move forward before air can reach the rest of the barrel. Flow is probably hurt a little because air must flow around the cap to get to the barrel, but it was the easiest to build design I could think of. If I were to build it again I would make a few changes. One being that I would give the bolt more movement so it could completely pass the loading port before the capped end cleared the tight-fitting area. This would give less airloss into the clip/hopper, but I would also have to find a new method to keep the ball from rolling forward(currently it is just the edge of the pipe that keeps it from rolling)

I am also upgrading my golfball valve to be multi-use, hopefully one use will be rapid fire, but that is going slowly. I just work on it when I am stuck on my other projects, which isn't too often. Eventually it should get done, but it is not my primary project ATM.
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Postby boogieman » Wed Sep 22, 2004 10:50 pm

Clide, I have been putting off reading this for a few days now, just because it was a cool first pic. I wanted to have a little time to read/study the design. I have to say, it is an ingenious way of making semi-auto. This would have to be the best, bar none, pneumatic design of the year.

A similar thing happened a while back. I was filling a QEV from on top of the diaphragm (a huge NO-NO, torn diaphragms can be hundreds of dollars). The EQ hole was big, about the size of a capital O. After each shot, the gun would refill. It had a similar effect of rapid firing. I didnt really think about it anymore after that.

I imagine, you could do the same with a sprinkler (cheap to replace if diaphragm goes). You would need a hole tapped in top, a tee coming off that, a very high flow blowgun off the tee, and a fill port off the other tee branch. (the EQ port in the diaphragm would have to be made much larger, but not too large to stop it from sealing)

The sliding piece on the back of the chamber, is it just a stock? How did you seal it up?

Again, you did one heck of a good job, that is a top notch project!
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Postby BC Pneumatics » Wed Sep 22, 2004 11:28 pm

'a very high flow blowgun off the tee'
Or a ball valve/sprinkler valve if you cant a good enough blow gun.
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Postby Mr.Plow » Thu Sep 23, 2004 12:37 am

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by boogieman
[I imagine, you could do the same with a sprinkler (cheap to replace if diaphragm goes). You would need a hole tapped in top, a tee coming off that, a very high flow blowgun off the tee, and a fill port off the other tee branch. (the EQ port in the diaphragm would have to be made much larger, but not too large to stop it from sealing)<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

I don't want to toot my own horn, but isn't what you're describing pretty similar to what I did with my semi-auto valve assembly?

http://www.geocities.com/boomstick989/auto.html
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