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piston probs :(

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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Unread postAuthor: experament-u2 » Sat Jun 02, 2007 1:06 pm

hi wrote:doubt it. think you just need a slightly larger tee.

you might get away with drilling holes, but that would weaken it, so i dont think its worth it.


would 4 holes (small ones) in front of the piston help?
if i would i might try that and see how it goes
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Unread postAuthor: hi » Sat Jun 02, 2007 1:10 pm

again, i dont know for sure because i have never done it. it might still not be enough. you can try it, but if it destroys your piston valve its not my falt.

i really think the best thing to do is to start over. it will cost another $10, so what.
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"physics, gravity, and law enforcement are the only things that prevent me from operating at my full potential" - not sure, but i like the quote

you know you are not an engineer if you have to remind yourself "left loosy righty tighty"
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Unread postAuthor: experament-u2 » Sat Jun 02, 2007 1:14 pm

hi wrote:again, i dont know for sure because i have never done it. it might still not be enough. you can try it, but if it destroys your piston valve its not my falt.

i really think the best thing to do is to start over. it will cost another $10, so what.


its kool if it dosnt work il havto pull it apart any way
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Unread postAuthor: hi » Sat Jun 02, 2007 1:16 pm

try firing it from a fair distance, because as i said, this could weaken it. maybe enough for the valve to shatter. if you are using a ball valve to accuate it, just tie a string to it to open it.
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"physics, gravity, and law enforcement are the only things that prevent me from operating at my full potential" - not sure, but i like the quote

you know you are not an engineer if you have to remind yourself "left loosy righty tighty"
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Unread postAuthor: keep_it_real » Sat Jun 02, 2007 1:20 pm

Put a smaller piece of pipe inside the original barrel. This will both move the piston farther back and it will allow for space. You can kill two birds with one stone :wink: .
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Unread postAuthor: spudthug » Sat Jun 02, 2007 1:25 pm

why is the tee critical to ur design? just get another tee that is bigger..
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4" piston valved cannon-half done..( i spilt my cement...)

Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
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Unread postAuthor: experament-u2 » Sat Jun 02, 2007 1:37 pm

keep_it_real wrote:Put a smaller piece of pipe inside the original barrel. This will both move the piston farther back and it will allow for space. You can kill two birds with one stone :wink: .


i might try this because i tried drilling a hole and its dosnt work
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Unread postAuthor: Suppressive Fire » Sat Jun 02, 2007 2:31 pm

You said the od of the barrel is far larger than the id right? If it is as thick as you say then remove half the thickness for the last 1/2in or so. 1.5 cm if you use metric I think.

Or if you have a piece of brass pipe that fits perfectly in the barrel take about an inch and epoxy it in the barrel so about a quarter inch is showing.
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Unread postAuthor: MrCrowley » Sat Jun 02, 2007 4:26 pm

Ok get a small reducer that fits in the I.D of your barrel. Stick that inside it and make it so the reducer goes to the centre of the tee, that should put some air infront of the piston for it to push it back.
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Unread postAuthor: jrrdw » Sat Jun 02, 2007 4:43 pm

Reinstall the barrel 1/3 the way into the chamber inlet. You could remove the piston and grind small channels to get air up front, but that will decrease proformance and weaken the tee. If you reinstall the barrel you will have to remove the stop sholder to incert the barrel further. Thats what i had to do with The Basterd, escept i used a smaller diameter pipe and lined and extended the sealing face further into the chamber inlets. I did it that way because i didn't want to rebuild the intire valve, a quick fix.

Edit: I didn't see the 2nd page, MrCrowley and i think alike sometimes, so theres 2 of us with the same idea, that should be worth something, like a try at our idea????
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Unread postAuthor: chaos » Sat Jun 02, 2007 11:55 pm

my tee is smaller than that one and i also dont have the barrel halfway, but i used a different piston design i used one similar to BTB's no o-ring piston.

i think if you made the center of the piston have more surface area it will work. ill d o a diagram
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Unread postAuthor: experament-u2 » Sun Jun 03, 2007 3:08 am

chaos wrote:my tee is smaller than that one and i also dont have the barrel halfway, but i used a different piston design i used one similar to BTB's no o-ring piston.

i think if you made the center of the piston have more surface area it will work. ill d o a diagram


would this work
drilling a hole through one side of the the piston so air can push againced the back?
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Unread postAuthor: jrrdw » Sun Jun 03, 2007 4:56 am

As long as your piston doesn't spin while moving back and forth, that mite work.
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Unread postAuthor: Modderxtrordanare » Sun Jun 03, 2007 4:45 pm

jrrdw wrote:As long as your piston doesn't spin while moving back and forth, that mite work.


He could also drill a few well planned holes so that even if it does spin, it will still have a hole (or parts of some) facing down.

But drilling holes in it makes me fear it failing, does your piston have a bumper in the back of the tee?
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Unread postAuthor: spudthug » Sun Jun 03, 2007 4:48 pm

it wouldnt matter if the piston spun... it would still get that air in there as long as hes not usin orings..
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4" piston valved cannon-half done..( i spilt my cement...)

Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
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