full auto Ball Valve design

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
Cannoneer
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Tue May 04, 2010 12:27 am

Ha! That's funny I build bows and often opt for knives and axes rather than planers files etc.
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Technician1002
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Tue May 04, 2010 12:28 am

I have been toying with a version for a gumball machine gun that would work on this principle. To preserve the chamber pressure, and yet have full chamber pressure for each shot, the chamber is broken into two chambers, a reservoir and firing chamber with a second rotary valve in between. Due to the fact both valves are open some at 45 degrees, I discarded trying to sync two ball valves with a timing chain, but instead am working on a sprinkler valve and electric switch to time the one valve off the other. Sequencing would be much like a propane meter for a hybrid. Only a metered charge would be permitted for each shot, but at full pressure.
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kydavies
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Tue May 04, 2010 12:35 am

i dontknow if im getting this but i would want to have a larger rear chamber that is connected to a smaller firing chamber with a rotating ball valve that is offset from the other more forward ball valve so that the firing chamber fills with air between each shot and maximizes the limited amount of pressure that i have, i will do a drawing tomorrow on paint likemy first one.
mikemurph wrote:yea, the ammo has been changed to a more aero dynamic projectile. it consists of the back half of a dart, and a hot glue ball
AHahahahah!!
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Tue May 04, 2010 12:57 am

kydavies wrote:because the ball valve will be spinning fast (i hope)
In this case however it would not need to spin, just on/off
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Gaderelguitarist
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Tue May 04, 2010 9:53 am

i dontknow if im getting this but i would want to have a larger rear chamber that is connected to a smaller firing chamber with a rotating ball valve that is offset from the other more forward ball valve so that the firing chamber fills with air between each shot and maximizes the limited amount of pressure that i have, i will do a drawing tomorrow on paint likemy first one.
Connect them with sprockets at a specific gear ratio and then to your hand crank with bike chain. You could end up with a mean looking setup. The gear ratio would just be 1:1 because you need to duplicate with the fill BV what the firing BV loses.
so many muchness
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Big-E
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Tue May 04, 2010 10:11 am

I've also considered a rotating ballvalve for an auto or semi-auto airgun.

One idea involved a clockspring, toothed cog and a sear. you would wind it up with a key (like an old air cane), charge with air; the cog and spring would allow a a quick, full revolution with each trigger pull. the valve would stop rotating via the sear, in the closed position. with a heavy enough clock-type spring, the valve would open and close in a very quick burst; making it almost like a hammer valve, but more like the shutter of a camera.

another idea used a single lobe cam that would charge the chamber with air from a resivoir (via a blowgun or pushbutton valve) just before the valve rotated into a firing position. every revolution would cycle this process again and again.

For the motorized version, I planned on using a 3/4" ballvalve, and a motor and controller from an electric scooter; It never came to pass though; it seemed too impractical to me in the long run. but believe me; others have thought of it before, and it is a viable idea.
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Gun Freak
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Tue May 04, 2010 10:25 am

I think it will work better if you connect it to a compressor so the chamber will have more pressure for each shot. I had this idea a few days ago also. I don't think it will work great because the time that the ball valve is closed isn't really enough for it to refill high enough for enough power for the next shot. But I'm sure there are ways to improve it... I hope to see more...
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clemsonguy1125
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Tue May 04, 2010 4:15 pm

What about 2 ball valves rotating, while the fronts closed, the backs open, this way you wont waste air and it will automaticaly refill the space between the 2 valves
That is all.
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Gun Freak
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Tue May 04, 2010 4:20 pm

that sounds good... but it would be way harder to build it with 2 rotating ball valves... also it would create more dead space but not a bunch
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clemsonguy1125
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Tue May 04, 2010 4:23 pm

Gun Freak wrote:that sounds good... but it would be way harder to build it with 2 rotating ball valves... also it would create more dead space but not a bunch
maybe grease up the 2 valves and put 2 motors of equal torque so they will spin at the same time, or come up with a system of gears
That is all.
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Gun Freak
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Tue May 04, 2010 4:23 pm

Yeah the gears would require machining unless you make them out of legos or something but those aren't strong enough so two motors would be better

I think he said it is for airsoft, and a 1/4" ball valve would be fine for that, and with some lube my 1/4" bv turns really good so a really weak motor could do it
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clemsonguy1125
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Tue May 04, 2010 4:26 pm

what about 2 bike gears with a bike chain on them, then you have to build some kind of turrent though
That is all.
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Gun Freak
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Tue May 04, 2010 4:37 pm

you mean hand cranked?
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clemsonguy1125
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Tue May 04, 2010 4:40 pm

Yeah, just add a crank and gear to one valve and another gear to the other, then just add the chain, ill make a bad sketch if you want
That is all.
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Gun Freak
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Tue May 04, 2010 4:45 pm

yeah sounds good... no diagram needed
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