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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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Unread postAuthor: Hubb » Thu Jul 16, 2009 11:30 am

Looks a lot more comfortable to shoot now with that trigger on it. I can also tell which steel pieces you had and which ones you had to get :lol: Seriously, though, I think the rusted fittings just add to it.

I'd personally like to see a video of this thing if nothing more than to hear it. Bet it's pretty loud dumping over 800psi through that valve or yours.
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Unread postAuthor: jeepkahn » Thu Jul 16, 2009 11:57 am

The noise is definitely in the range of needing ear protection...

Hopefully, I'll have the bipod built for it by the first of the week...
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Unread postAuthor: jeepkahn » Mon Jul 20, 2009 3:22 pm

Video's on post #1.... If a mod can embed if I haven't figured out how yet, it would be much appreciated...
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Unread postAuthor: jackssmirkingrevenge » Mon Jul 20, 2009 3:26 pm

very impressive, but the tags are the wrong way round :)

(youtube)http://www.youtube.com/watch?v=Vn98lJeHgPs(/youtube)

replace the round brackets with square ones and you should get:

[youtube]http://www.youtube.com/watch?v=Vn98lJeHgPs[/youtube]
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Unread postAuthor: jeepkahn » Mon Jul 20, 2009 3:41 pm

Thanx JSR...

And just for referance here are pics of the red metal with .22lr vs .40cal minimodgun shots... .22lr with blue arrows and the .40cal with pink arrows... I know a .22lr ain't real strong, but it should show that I'm not punching holes in thin/cheap tin with the decimater... the shots are from 30yds btw...

notice the neat punches from the decimator...
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22vs40cal.JPG
22vs40cal2.JPG

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Unread postAuthor: jackssmirkingrevenge » Mon Jul 20, 2009 3:49 pm

jeepkahn wrote:I know a .22lr ain't real strong, but it should show that I'm not punching holes in thin/cheap tin with the decimator.


No doubt about the strength of steel drums :)

One think to note though is what ammunition were you firing from the 40 cal?

If it was steel shot then the comparison is a little weak, because I'm sure steel cored bullets in the 22LR would punch through easily, projectile hardness has a lot to do with penetration. Impressive results regardless however, kudos :)
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Unread postAuthor: Davidvaini » Mon Jul 20, 2009 3:50 pm

very impressive videos, I especially like the camera shot from behind so you can really see all the action (okay that sounded a little Pron like....)

Anyways really good penetration, I love to see high pressure cannons :D
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Unread postAuthor: jeepkahn » Mon Jul 20, 2009 4:38 pm

The bearings were indeed steel, so yes the comparison is weak, but the pics were more to show the metal's strength... the red metal is 1/8" and I'm not sure what gauge the barrell is but it ain't thin...
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Unread postAuthor: jackssmirkingrevenge » Mon Jul 20, 2009 9:55 pm

jeepkahn wrote:I'm not sure what gauge the barrell is but it ain't thin...


I believe the standard thickness is about 1.5mm, so around 16 gauge. A formidable target, but the Decimator doesn't seem to realise this :)
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Unread postAuthor: mark.f » Tue Jul 21, 2009 3:26 am

Video looks good. That muzzle blast looks far more impressive than most rifles I've seen.

Also, looks like you've figured the embedding out (too late). :roll:
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Unread postAuthor: jeepkahn » Tue Jul 21, 2009 1:36 pm

As impressive as the muzzle blast is, I REALLY need a muzzle brake on this thing... I'd like to do one similar to the one pictured below...

and is fitted with a high-efficiency muzzle brake which reduces the felt recoil to about the level expected of a 7.62x51mm NATO-chambered rifle
And this fires the .50cal BMG round. Quite an effective brake....
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800px-PGM-Hecate-seul-img_1008.jpg
800px-PGM-Hecate-seul-img_1008.jpg (21.67 KiB) Viewed 782 times

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Unread postAuthor: jackssmirkingrevenge » Tue Jul 21, 2009 1:51 pm

Why not make a multi-layered brake, I particularly like the Serbu "shark gill" on their BFG-50

Image
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Unread postAuthor: jeepkahn » Tue Jul 21, 2009 3:15 pm

jackssmirkingrevenge wrote:Why not make a multi-layered brake, I particularly like the Serbu "shark gill" on their BFG-50

Image


I Do like the looks of that... Time to get to work.... :D
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Jeepkin's brazing job.

Unread postAuthor: Technician1002 » Fri Jul 24, 2009 10:33 pm

I'm posting this for the rest of the troops. Jeepkahn and I have been in a PM discussing the brazing job. I edited his picture to show his job next to an original job. The original used silver brazing solder. I can tell from the color and the drips. It adheres well to copper and flows with a wetting action creeping into joints. The brass on copper doesn't do so well. It tended to bunch and might have not flowed into the joints.

The silver brazing solder does not use flux on Copper. As such the joint won't have pockets of flux that may leak, but has a nice flow of wet solder.

On my cannons I brazed them and had the same difficulties. Brass tended to get pockets of flux where after cleaning, would create pinhole leaks. I had to use 3 passes to fill the joint on my cannon and create a smooth flowed brass joint.

To examine a silver brazing joint, here is a fitting a made a couple years ago. The end of the pipe was hammered flat and brazed shut. The solder wicked into the joint. There is no question that it wicks onto the copper wetting it. A hose barb was created by simply drilling the side of the 1/2 inch pipe and brazing in a small tube. This holds pressure with no leaks. The solder out on the pipe is from the wetting of the solder.

A welding torch is required to use this.
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SilverBrazing.JPG
One of my Silver Brazing solder projects.
Bottom brazed.JPG
My Brazing job on the 2 inch launcher. It looked bad and leaked on the first couple passes. Brass bunched and pockets of flux made leaks. More time and care fixed it.
DecimatorBraze.jpg
Decimator brazing. There appears to be a silver braze job on the right and the brass brazing on the left. The brass didn't flow well. It possibly didn't wick into the joint. This joint is to be treated with caution.
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Unread postAuthor: jeepkahn » Sat Jul 25, 2009 7:54 am

On that note, Because the brass brazed end was so ugly,I did have this hydrotested before being put into use with way more than a 4:1 safety margin...

The joint on the right is actually using a rod called Blockade...

Here's a link to the website. http://www.harrisproductsgroup.com/cons ... .asp?id=31

I only had a sample of it to use that's why there are 2 differant rods used, had I known how well the blockade was going to work I would've gone ahead and bought some more....
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