3/4" exhaust valve cannon

[jackssmirkingrevenge]

I built this last year, one of the most powerful I've ever built using my unique (as far as I've found so far online) construction technique featuring high-strength epoxy as opposed to standard fittings. It's got a 34" barrel and is filled/fired through the same schrader valve. The reason I can do this and still get great performance is the tiny pilot volume, as the piston can only move back a little more than 1/8" (approximately 25% of the barrel diameter and all that is neccessary for maximum flow). The cast epoxy piston is also lightweight, a near perfect fit and very low friction.

For more detailed information on using epoxy, check out the how-tos here and here.

The beast:




A diagram of the breech end internals:




I had a lot of fun with this particular creation, here's the damage videos.

cell phone shot with a marble:

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and the bits I managed to recover:




coffee can filled with water shot with a marble:

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entry/exit holes:




coffee can filled with water shot with multiple lead BBs:

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coffee can shot with a whiteboard marker:

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computer mouse shot with a marble:

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computer speaker shot with a marble:

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flatbed scanner shot with a marble:

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electric kettle filled with water shot with a marble:

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diving mask shot with a marble:

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and last but not least, xmas angel with a head full of red paint

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[experament-u2]

that is a great idea and desgin im sure it will inspire other people including me

and lots of good videos

[shud_b_rite]

Awesome video's. That cannon is super powerful. Any idea what fps it shoots at?

[jackssmirkingrevenge]

I don't have the facility to chrono projectiles over 6mm in diameter, however according to GGDT when pressurised to 110 psi it fires a 10 gram glass marble at approximately 480 feet per second.

[mopherman]

your pics are busted. i want to see em so plz fix
where did you get your valve?

[Brooner115]

ya man i cant see the cannon all i see are the things getting destroyed by the cannon(that i cant see)

please fix because it looks like a beast from the vids

[integral]

lol that xmas deco cracked me up man... brain matter all over the box!
gotta find a load of old toys to fill with red paint

[jackssmirkingrevenge]

lol that xmas deco cracked me up man... brain matter all over the box!
gotta find a load of old toys to fill with red paint

if you liked that, you'll love my website

Here's the pics in the original post, don't know what's up with photobucket

[integral]

omg hahahahahaha that site is the shiz!

[A-98]

yup, you are jesus.

im suprised i hadnt found this one, given that im almost always on. it appeared in the random cannon area.

i think i might hae to borrow this epoxy idea, but i might have just found a machinist that could help with PVC.

this is one of the most powerfull cannons i have ever seen for its size, and it has inspired me! im going to make a piston gun if its the last thing i do!

[lukemc]

how does the air get by the piston you said it makes a good seal

[jackssmirkingrevenge]

how does the air get by the piston you said it makes a good seal

Since it's cast in the actual tube it travels in, the piston is a near perfect fit, but obviously there are no rubber seals or o-rings so it's not a 100% leakproof system, which works out fine.

[zeigs spud]

1-why doesn't that foam sheet break when air is released, if what i see is that is a diaphram activated cannon

and how do ur realease air fast enuf through a scharder valve??

[Scope]

That is a pretty sick cannon!!
you make some crazy stuff!!

[jackssmirkingrevenge]

1-why doesn't that foam sheet break when air is released, if what i see is that is a diaphram activated cannon

and how do ur realease air fast enuf through a scharder valve??

The foam sheet isn't part of the structure as such, it's really just there to hold the epoxy while I pour it, all the strength comes from the epoxy. There's no diaphragms anywhere, it's just a normal piston cannon, but instead of the rubber seal being on the face of the piston, it's stuch to the end of the barrel.

I can afford a schrader for piloting because the pilot volume is only 1/5 of a cubic inch