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Compact All Metal Cannon

Posted: Fri Jun 29, 2007 10:35 am
by goose_man
This is my most recent cannon. It shoots 1/4" ball bearings from a brass barrel that fits them perfectly. It is somewhat coaxial I guess as you can see from the pictures. It uses another breech-loading ball-valve mechanism like my last pneumatic.

It uses a 1/4" QEV actuated by a blowgun. The filling valve is a shrader. At 100 PSI it shot through many layers of foam-core board and lodged itself deep in a wall board. I have yet to test its range due to lack of space. Here's the pictures:

Full Veiw:
Image

Breech Open:
Image

Breech Closed:
Image

Back End:
Image

Comments, Suggestions, and Criticism is welcome!

-goose_man

Posted: Fri Jun 29, 2007 10:56 am
by Specialist
tha ball valve loading system is awesome! who would of thought to use that. nice gun btw.

Posted: Fri Jun 29, 2007 11:05 am
by SnowFlox
loading system is very sweet indeed !

nice gun !

Posted: Fri Jun 29, 2007 11:06 am
by Acdcmonkey1991
Thats a nice loking cannon. :D
BTW: specialist, look at the Wasp M2k I think it's called, that has the ball valve loading system to... I'm too lazy to find the link right now... :lol: :D

Posted: Fri Jun 29, 2007 11:23 am
by spud yeti
Flipping sweet cannon! I love all metal cannons, they my favourite!
I take it you use a compressor, right?
A truly amazing gun... only one question, why did you use that short piece of hose instead of just the metal pipe???

Posted: Fri Jun 29, 2007 11:31 am
by potatoflinger
That's a great looking gun, I used the same loading system in my sniper, and they work great.

Posted: Fri Jun 29, 2007 4:00 pm
by Pete Zaria
I really like the semi-coaxial style, how you used the space around the barrel for additional chamber volume.

How did you seal the barrel into the larger pipe? Epoxy, JBweld, something crazy with fittings?

Did you mod the blowgun? I assume so, though I doubt it matters for piloting a 1/4" QEV (You could probably pilot that valve with a pinhead...).

What's the lowest-rated part? The hose, I assume?

I bet the performance is great with those teeny ball bearings. I'd try making some darts for it (though you'd have to muzzle load them).

The hose at the bottom is the only part I don't like. It'd be nice if you could figure out a way around that, but I see the problem: those fittings don't line up well enough to use a nipple there.
I'd consider trying to bend a fitting or pipe (maybe using copper, it's easier to bend...) or using JBWeld to make a little angle adapter (I've used JBWeld in some pretty high-pressure, high-stress applications before and have always been impressed with the results).

Since it looks kind of like an SMG already, a mock silencer (that'd fit over the last few inches of the barrel, making the whole barrel look much bigger) and a shoulder strap would be cool accessories :)

Nice work.

Peace,
Pete Zaria.

Posted: Fri Jun 29, 2007 4:01 pm
by goose_man
Thanks for the compliments guys!

I don't actually have a compresser at the moment so I use a 12gram CO2 to tire valve device from the bicycle shop near me.

I used the piece of hose because I can't solder well enough yet and try making a square with 4 threaded elbows- it cannot be done.

-goose_man

EDIT: you beat me to the post:
Anyway, I used epoxy to fill/secure the gap around the barrel. I originally designed it to be all copper plus a brass barrel but the whole learning to solder got in the way. I'm still working on that though. Also, no, the blowgun isn't modded.

Posted: Sun Jul 01, 2007 3:46 am
by Mitchza89
Now thats a cool looking cannon. Well done mate. :D

Posted: Sun Jul 01, 2007 4:34 am
by Pete Zaria
@goose_man,

I was thinking about your "making a square with 4 threaded elbows" problem... what about compression fittings? It seems to me that you could use two NPT-to-compression elbows, and a nipple with compression fittings on the ends between them (hope that makes sense).

Otherwise, I'd get creative with some JBweld or high-strength epoxy.

Awesome gun. Hope you can figure out a way around that hose, because that's the only thing holding it back from being "grade A".

Peace,
Pete Zaria.

Posted: Sun Jul 01, 2007 6:41 am
by Hotwired
I particularly like the ballvalve breech :)

I don't think it is possible without a special fitting to replace the hose with metal.

Threaded fittings can't make a square unless you have a swivel fitting in there somewhere or perhaps a compression section which would cost quite a bit more.

Posted: Sun Jul 01, 2007 12:38 pm
by Modderxtrordanare
Hotwired wrote:Threaded fittings can't make a square unless you have a swivel fitting in there somewhere or perhaps a compression section which would cost quite a bit more.
Give me a vice, and a hammer. I can make them fit.

Posted: Sun Jul 01, 2007 12:46 pm
by 666lucky693
the ball valve loading is a great idea

Posted: Sun Jul 01, 2007 2:26 pm
by crazymoron010
I really like the cannon. Great idea for the ball valve. how long did it take you to make? I'm not exactly sure how qev's work but isn't the chamber all before the valve?

Posted: Mon Jul 02, 2007 7:59 am
by goose_man
Pete: Yeah, I probably could use compression fittings, wish I'd thought of it.

crazymoron010: The chamber is all before the valve as far as air flow goes, but not as far as physical placement goes. The QEV is basically just a really well designed barrel-sealing piston valve.

Thanks for all the compliments and suggestions guys!

-goose_man