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CoAx 180psi Piston Valve

Posted: Mon Aug 07, 2006 2:30 pm
by simonr
Thought I'd introduce myself (as a newbie, least on here) by showing you my air cannon......
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As you can see it's a co-axial barrel/reservoir design with a piston type valve.
It's built from 3" and 1.5" thin wall stainless tube made for pressurised steam. The other bits & bobs were turned out of HDPE. It barely leaks at all up to about 50psi, but above that the air whistles out all over the place. For higher pressures, I covered it in Hot Glue which has sealed it pretty good!
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Filling is via this PCL connector and firing is achieved just by disconnecting the PCL, discharging the pressure in the void behind the piston.

At 180psi, it can achieve flight times of about 28 seconds. No idea what that translates into in terms of muzzle velocity or range - but it looks a lot!

Best ammo at this time of year is apples from the tree in my garden. If you use the barrel to 'core' an apple, it is an almost perfect fit and makes a good sharp crack sound upon firing, compared to the low thud you get firing most other things.

Si

Posted: Mon Aug 07, 2006 3:30 pm
by M3NT4L
Thats a cool cannon im looking into building one myself but metal piping is hard to find and i cant weld. And you said you fired apples, have you tried potatoes because they are much easyer to find and fire much better, also if you have some leftover pipe from the barrel you can clog one end and fill it with water freeze it and thats one way to make great ammo. 28 seconds is a large flight but you can get much more out of that cannon.

Posted: Mon Aug 07, 2006 5:07 pm
by drac
The fact that it's made out of steel makes it amazing!!! What kind of damage do you get out of that?

EDIT: It's also nice to see someone new on the forums who uses proper grammar. It's a breathe of fresh air when all you experience is "zomg look @ mah col new ptato gun11one!!eleven11!"

Posted: Fri Aug 11, 2006 2:22 pm
by boilingleadbath
Nice cannon.

You might try modeling it with the GGDT to find out (within a few percent) how it's preforming. (search the spudwiki for "GGDT")

Posted: Thu Nov 02, 2006 6:34 pm
by Kaiser Bill
nice looks very tidy what how are all the components attacheted together?

Posted: Thu Nov 02, 2006 10:54 pm
by drac
Noone bothers to read anymore? Especially when kicking up topics?

He said he covered it in hot glue...

Posted: Thu Nov 02, 2006 10:57 pm
by SpudStuff
He welded it then covered it in glue.