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Decimator video UPDATE 07-20-09

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Decimator video UPDATE 07-20-09

Unread postAuthor: jeepkahn » Tue Jul 07, 2009 1:48 pm

Haven't gone unregged yet but the first time I fired it with a 1"ballbearing @600psi it kicked so hard it broke off the brass fitting that the blowgun was attached to, and put me on my butt... After that I put on a 3/4" street 90 with the ballvalve and filler adapter and use the ball valve as a trigger(this friday I'll be getting a check/filler nipple and will run it off the back of a tee that'll replace the str90 and use the 1/4" ball valve as a trigger only<the>)....

I'll post some damage pics later.....

I used Iron for the chamber because I didn't have the money for brass/copper fitting for copper chambers yet....

Specs are: 1.5" porting , toolie styled barrel sealer, 1" type k barrel, 3/4" qev as the pilot valve...

I've also got to build a mount/tripod for this thing, it weighs about 30lb and will bruise your leg if you brace it against your thigh...

I also forgot to mention how much of a pain it is to make a piston that'll handle 600psi+ without self dectructing the sealing face every shot...

And yes, thats my gawdawfull ugly brazing job on the piston chamber, and LIBERAL use of pipedope on the threaded portions....

[youtube]http://www.youtube.com/watch?v=Vn98lJeHgPs[/youtube]

[youtube]http://www.youtube.com/watch?v=LnHpcvsm90w[/youtube]

[youtube]http://www.youtube.com/watch?v=jiikxvtvD1w[/youtube]
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Attachments
decimator.jpg
needs polished and going to upgrade the filling/firing method but It works for now...
Last edited by jeepkahn on Mon Jul 20, 2009 3:36 pm, edited 11 times in total.

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Unread postAuthor: jackssmirkingrevenge » Tue Jul 07, 2009 1:53 pm

Looks awful but pretty is as pretty does, looking forward to the damage pics :)

Also, if you run out of air, looks like you can swing it from the barrel as a war-hammer :D
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Unread postAuthor: jeepkahn » Tue Jul 07, 2009 1:56 pm

jackssmirkingrevenge wrote:Looks awful but pretty is as pretty does, looking forward to the damage pics :)

Also, if you run out of air, looks like you can swing it from the barrel as a war-hammer :D


But with a 50lb co2 tank, air is plentiful.. :twisted:

As you can tell by the pics, the wood is not rotten and that's a ' steel ball for size index...
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Attachments
damageentry.jpg
most of the pics don't do justice because the entry wounds don't look like much but the exits are impressive
damageexit2.jpg
damageexit.jpg
spoolsize.jpg

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Unread postAuthor: neeewwww » Tue Jul 07, 2009 2:31 pm

Beautiful war-hammer... Notice you can use your warhammer as AirGun.

I like the... ... "old" look.
Piston pics?

o>

-- Edit

*I found the piston...
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Unread postAuthor: jeepkahn » Tue Jul 07, 2009 3:05 pm

I was going for the same look as the AMS Avalaunchers, hence the sidebyside chamber layout, when I get the copper chambers built the weight an bulky look will hopefully go away... but I don't know if you want hold something lighter while firing when the recoil is so ferocious...
I'm sure one or 2 on here have fired a highpressure large bore gun, but those who haven't....It's a definite wakeup call....
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Unread postAuthor: spudtyrrant » Tue Jul 07, 2009 3:20 pm

jeepkahn wrote:But with a 50lb co2 tank, air is plentiful.. :twisted:
with a 50lb co2 tank co2 is plentiful :lol:
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Unread postAuthor: jeepkahn » Tue Jul 07, 2009 3:23 pm

spudtyrrant wrote:
jeepkahn wrote:But with a 50lb co2 tank, air is plentiful.. :twisted:
with a 50lb co2 tank co2 is plentiful :lol:


I stand corrected...lol... Smart@$$.... :D
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Unread postAuthor: mark.f » Tue Jul 07, 2009 6:10 pm

Looks... um... good. :D

Need more details on piston, sealing face, etc. Good job!
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Unread postAuthor: Clarke » Tue Jul 07, 2009 6:17 pm

Cant wait to see some damage vids. High pressure damage is always impressive especially at 600 PSI
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Unread postAuthor: THUNDERLORD » Tue Jul 07, 2009 6:29 pm

Sweet!! "war hammer".
I was thinking it could have two "45's" off the "Cross" between the chambers and valve.
That way it could be strapped on the shooter's wrist, like a bull-pup pistol maybe. 8)
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Unread postAuthor: jackssmirkingrevenge » Wed Jul 08, 2009 5:58 am

Very impressive penetration, any idea at what rate it screams through the air?
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Unread postAuthor: jeepkahn » Wed Jul 08, 2009 8:54 am

Some better pics of overall size and layout, as well as the fire control that will be upgraded soon... Also a pic of the c02 adapter setup I use to fill with....

I've tried to get readings 3 times, but at 6ft away firing 16" above the chronie, the muzzle blast kept knocking the chrony off the stand, I'm going to mount it to a steel plate 12"x12"x.125"thick and clamp that to the picnic table...

The piston is 3/8" threaded rod, 2 3/8"x1.5" washers spaced 2" apart with a rubber "flapper" seal that allows air to enter chamber but 100%seal on firing, the sealing face is .25" flange gasket rubber(we have a local company that makes large high pressure flange gaskets And I get the scraps for free, durable hi durometer stuff), with a fender washer behind and a smaller washer in front( the problem I was having in the begining was too small a washer on the barrel side and when I'd fire it the sealing face would get launched as well).... this piston has more than required travel (about 5/8") but I only did that so that the nut and rod can pull back even with the breech....
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Attachments
decifiringcontrol.jpg
decibetterview.jpg
co2fillersetup.jpg

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Unread postAuthor: THUNDERLORD » Wed Jul 08, 2009 10:55 am

Looks even more awesome in the close-up pics.
That barrel grip looks a little...scary to hold right there.
Is the barrel sleeved?

...@600psi it kicked so hard it broke off the brass fitting that the blowgun was attached to, and put me on my butt... After that I put on a 3/4" street 90..

Recoil :D
So you're sure the recoil broke the brass and it wasn't failure???

BTW:Brass fittings are confusing to me, the other day my (cast brass) garden hose faucet body was spraying water streams through tiny holes in it. :shock:

Must've been due to freezing water...Which of course got me to wondering what pressure water-ice could potentially generate and thoughts of a "green" design where water freezes at night, compressing air for motors...It would only work in certain climates and the set-up would probably require ingenouity due to the slow freezing rate of large bodies of water. 8)
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Unread postAuthor: jeepkahn » Wed Jul 08, 2009 11:50 am

THUNDERLORD wrote:Looks even more awesome in the close-up pics.
That barrel grip looks a little...scary to hold right there.
Is the barrel sleeved?

...@600psi it kicked so hard it broke off the brass fitting that the blowgun was attached to, and put me on my butt... After that I put on a 3/4" street 90..

Recoil :D
So you're sure the recoil broke the brass and it wasn't failure???



actually the nipple connecting the tee to the qev sheared, so yes, I would say that the recoil did it, especially since this thing has a teensy bit of recoil.... :shock:

the grip on the barrel is just for carrying it, that's where it balances at...I'll be building a bipod for it this week...
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Unread postAuthor: jeepkahn » Thu Jul 16, 2009 8:44 am

Here's the updated triggering mechanism I built to replace the blowgun triggered broken one.....

Also pics of the decimater "field stripped", the piston(showing the toolie design), and the piston/pilot chamber( gives a good visual of how I build the "cup seal" rear piston seal that is so effective for allowing only one way flow for filling and 100% seal against backflow on firing)...

The reason for the big rubber stopper behind the barrel sealing face is because with unregged co2 and a washer directly behind the sealing face, a coupla shots would destroy the sealing face by turning the barrel into a hole punch, the rubber stopper helps cushion against that....

Do you think a 3/4" qev is overkill for a 2 cubic inch pilot volume??? :D
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Attachments
DECIAAPART.jpg
DECIPISTON.jpg
DECIPISTONCHAMBER.jpg
DECITRIGGER.jpg
DECIFIRINGPOSITION.jpg

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