Alrighty, another hammer idea from me. probably thought up years ago by a certain epoxy enthusiast, sigh. Ah well
DIAGRAM-
labels-
1- air in
2-bushing in valve body
3-service plug
4-poppet valve with sealing bolt for blow forward action
5-you get a cookie if you can find #5, its on there
6-bushings for spring housings, bored out so the beige barrel can slide
7-sear housing
DAMNIT! the beige barrel is actually supposed to extend THROUGH the brown sliding piece about 2mm
EDIT- DAMNIT AGAIN! cant get the pic up. I'll have at least a photobucket image up soon. I promise
EDIT2- diagram up
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bluerussetboy wrote:when your barrel slides onto #4-poppet valve wont that seal the barrel?
Yes, my diagram is a little deceiving though. the beige barrel and the brown piece both slide and the bash open the poppet. the air pressure from the open poppet pushes the barrel back the the original cocked position and the air finally escapes. The beige barrel is actually supposes to extend THROUGH the brown piece a little to provide surface area to recock.
Its a lot like JSR's blow forward bolt, except the barrel peice is acually a hammer and a bolt at the same time
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That really doesn't seem much different than designs Ant has posted.
A big issue will be that the hole that the sear apparently goes through will leak most of the air out when it is released.
mopherman wrote:Alrighty, another hammer idea from me. probably thought up years ago by a certain epoxy enthusiast
One slight concern is the size of the port that 4 is sealing, it's going to need a fairly hefty whack to open it even at relatively low pressure.
Yup, I'm going to make the hammer carriage pipe a tiny bit coaxial so i can have some wiggle room. btw, does anybody know how to find out how much force a spring exerts, other than putting it on my bathroom scale?
EDIT@ hawk- the trigger is no big deal, i can always put the sear between the two spacers in the front.
Last edited by mopherman on Wed Jan 30, 2008 11:29 am, edited 1 time in total.
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jackssmirkingrevenge wrote:Nothing wrong with the bathroon scale if it's accurate enough.
Not accurate at all according to the 'rents anyway, would the spring pressure be in N?
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Yeah I was just ganna say. I made this design work in my P.4 Project I also have a design there of the auto blow forward bolt thingy. I made an animation in interactive physics and it all seems to work. Atm I am looking at the physics behind it, I will go from the formulas to the real thing. As the masses, spring tension, air pressure and speeds are very important I will go to it this way. From experience I noticed that it will be very hard to find the right hammer mass and springs using trial and error. I will report in when I am finished with the calculations. Like this I hope I will give a (broad)bandwidth for a working automatic breech system. Btw good luck with ur airgun. I made mine using copper and aluminium pipes; it should work with pvc pipes. This design gives u a high effeciency and high power so I wonder how it would work on the big scale:)
ant wrote:Yeah I was just ganna say. I made this design work in my P.4 Project I also have a design there of the auto blow forward bolt thingy. I made an animation in interactive physics and it all seems to work. Atm I am looking at the physics behind it, I will go from the formulas to the real thing. As the masses, spring tension, air pressure and speeds are very important I will go to it this way. From experience I noticed that it will be very hard to find the right hammer mass and springs using trial and error. I will report in when I am finished with the calculations. Like this I hope I will give a (broad)bandwidth for a working automatic breech system. Btw good luck with ur airgun. I made mine using copper and aluminium pipes; it should work with pvc pipes. This design gives u a high effeciency and high power so I wonder how it would work on the big scale:)
well, as for mass, I was thinking i would just keep stacking washers untill i find a good weight for my spring. Frankly, I cant do s hit about the spring. lol
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mopherman wrote:
well, as for mass, I was thinking i would just keep stacking washers untill i find a good weight for my spring. Frankly, I cant do s hit about the spring. lol
Well the prepressure on the spring can be varied. So for a spring u have different springs with different k costants and you can give is different x prepressures. This makes it so complicated. Maybe a very heavy hammer with a certain prepressured'' spring would give a bigger bandwidth for opperating pressures the automatic cycle would work at.
Btw here is a vid how the it would look like: [youtube][/youtube]
Alright, ant. What diameter openings do you usually use? I'm begining to think that 3/4 is massively to large, but my carriage spring is like 5/8 in o/d. I think i can choke the carriage to 1/2 towards the end though. what pressures do you run at?
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mopherman wrote:Alright, ant. What diameter openings do you usually use? I'm begining to think that 3/4 is massively to large, but my carriage spring is like 5/8 in o/d. I think i can choke the carriage to 1/2 towards the end though. what pressures do you run at?
The problem is that the valve I used on that gun I was never able to remake as it kept leaking. The valves I use now are easier in remaking but have less airflow I think; so I should work on that. I work with 8mm innerdiameter piping for the barrel to fit into. (the barrel is the hammer) My valve heads that I use now are about 9mm in diameter. The outercopper pipping I uses is 10mm. So it gives little space for the air to flow-by. I run at 7atms of pressure now. I think I did as well when the movie was made. But I didnt have a compressor with gauge back then. I think a good valve with sufficient space for air to flow by is one of the keys to this automatic design.
wow, just saw your video edit. Thats fast firing there, how long does it take to run out of air in that little bottle?
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I think it was a 0.5 or 1.5 bottle I am not really sure anymore. It must have been a 1.5L bottle as I had above 30 shots. But yeah u can time how long it takes to empty. The problem is that the rate of fire is waaay too fast. This video is kinda fake as well as I clogged up the barrel, so it cant be really used to shoot. But if you place one clogged up barrel below a real barrel setup (with two valves) then it could work. Maybe semiauto with a tippmann style trigger and sear.
anyway, would the spring pressure be in N?
