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my first pneumatic cannon

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: frozebyte » Fri Jul 03, 2009 8:47 am

i think it has been mentioned somewhere, but you can get free shrader valves from a bicycle shop where there is a an abundance of broken inner tubings ready for the dumpster.
depends on the situation, you might be able to ask the shopkeeper for one free and cut the shrader off it.
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Unread postAuthor: geardog32 » Mon Jul 06, 2009 11:54 pm

ok so i have searched the wikki and with the search box but i want to use ggdt to model my gun but i do not know what to set some settings to like the valve type(i assume generic because it is a 1 inch sprinkler) flow coef, and open time. are there suggested values for these?
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Unread postAuthor: Technician1002 » Tue Jul 07, 2009 1:53 am

geardog32 wrote:ok so i have searched the wikki and with the search box but i want to use ggdt to model my gun but i do not know what to set some settings to like the valve type(i assume generic because it is a 1 inch sprinkler) flow coef, and open time. are there suggested values for these?


The site you downloaded GGDT has a design library page which includes several models of sprinkler valves. It includes a 1 inch unmodified and modified version.

http://www.thehalls-in-bfe.com/GGDT/
Design library tab on the left..

Orbitmaster 1 inch modified;

Valve Type Chamber Seal
# of Valves 1
Flow Coef 23%
Seat Diam 1.2 in
Dead Vol 3.1 in^3
Piston Diam 2.0 in
Piston Mass 22 gm
Vent Diam .15 in (1)
Pilot Vol 1.1 in^3 (2)
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Unread postAuthor: geardog32 » Tue Jul 14, 2009 1:38 pm

one more thing that i did not even notice till now but, i see that most people who have gauges and fill valves seem to be in places where there are two layers of pvc like at a coupling. i was just wondering if this is going to be a problem on my gun, since i tapped them right into the cylinder. if so i can just get some air fittings and fill them with epoxy and then epoxy/screw them into the existing holes and drill two more holes in the coupling.
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Unread postAuthor: FORE!!!! » Tue Jul 14, 2009 4:26 pm

geardog32 wrote:one more thing that i did not even notice till now but, i see that most people who have gauges and fill valves seem to be in places where there are two layers of pvc like at a coupling. i was just wondering if this is going to be a problem on my gun, since i tapped them right into the cylinder. if so i can just get some air fittings and fill them with epoxy and then epoxy/screw them into the existing holes and drill two more holes in the coupling.


it really should of been tapped into a twin layer of pipe,and by simply pluging off the original hole ur defeating the purpose altogether,the weak hole is still there just with epoxiy in it,,best bet to leave it and make sure when u fill ur not standing in front of the valva
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Unread postAuthor: geardog32 » Tue Jul 14, 2009 5:17 pm

so are you saying that the valve and gauge might blow off or that the whole chamber is compromised? if im afraid of the gauge and fill valve flying out i think it would be better to relocate them to the coupling. then to plug up the existing holes i could get some threaded brass plugs and screw them in with some epoxy. if i have compromised the integrity of the whole chamber i either need some advice on how to fix it or scrap it and start over :(.
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rebuild

Unread postAuthor: geardog32 » Wed Jul 15, 2009 1:58 pm

since my fill valve and guage are at the very rear of the camber im just going to cut off the last four inches and rebuild the bend in the back so its like a fresh start without having to rebuild the whole chamber and at only a loss of about 4 inches. then i can just tap the fill valve and gauge in the coupling. thanks for your help guys and or girls.
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rebuild

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