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mini 6mm PVC cartridge

Built a miniature 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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mini 6mm PVC cartridge

Unread postAuthor: Blue Lagoon » Fri Sep 14, 2007 8:16 am

Hi! (I could be a little bit Engrish :D )

I've recently made my first "spud gun"... well actually it's a small piece of PVC (2cm diameter x 6cm length). Both ends superglued with rubber O-rings (the ones you use for watertaps). On one end I've slightly plugged in a main wire (with 2 or more colored wires inside) to get a spark from a piezo ignitor. On the other end, I've enlarged the hole of the o-ring to fit in a 6mm BB.

For combustion I use standard hairspray and for oxygen i use a dual action bicyclepump (6 pumps)... it works awesome! There's no misfire and the combustion is much more agressive.

After this succesfull test, my next step is to seperate the piezo igniter and use some kind of connection (metal to metal) to pass the spark/energy from a handguard with a piezo trigger to the bolt loading the PVC round.

Later on I'll figure out a way if the recoil is enough to eject the empty case.

I'll post some pics soon! :wink:
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Last edited by Blue Lagoon on Sun Sep 16, 2007 11:16 am, edited 1 time in total.

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Unread postAuthor: jackssmirkingrevenge » Fri Sep 14, 2007 8:55 am

herro! ( :D )

Does this mean you've made a hybrid cartridge? If so, photos/diagrams please. You might want to check out my own efforts here.
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Unread postAuthor: Blue Lagoon » Fri Sep 14, 2007 1:59 pm

hiya! ...indeed the concept is identical! :shock:

Cool project you got there! 8)
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Unread postAuthor: Blue Lagoon » Sun Sep 16, 2007 10:44 am

Here are some pics. Next step is to build the magazine holding area which holds the assembly together shown in the 1st pic. :)
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Attachments
DSC_0210.jpg
parts
DSC_0210.jpg (14.84 KiB) Viewed 975 times
DSC_0213.jpg
When the bolt moves back it hooks the empty case along to a point its ejected.
DSC_0213.jpg (14.02 KiB) Viewed 975 times
DSC_0212.jpg
Complete assembly
DSC_0212.jpg (12.52 KiB) Viewed 967 times
Last edited by Blue Lagoon on Sun Sep 16, 2007 10:48 am, edited 1 time in total.

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Unread postAuthor: jackssmirkingrevenge » Sun Sep 16, 2007 10:47 am

The question is, will the cartridge have enough energy to eject the cartridge? The 6mm carts I had made were pretty weak. Can you post a cutaway diagram of your actual cartridge?
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Unread postAuthor: Blue Lagoon » Sun Sep 16, 2007 11:04 am

Well I'm planning to use the trigger as a source to move the bolt back by using gears, just fingerpower. Mainly because the bolt just only moves back and forth by 1 inch.

After the bolt moves back, the empty case will be pushed out by another case below uhm like this (got my picture order messed up)

The hook part is quite flexible allowing the new round to move between it. The hook will eventually snaps into place when bolt is moving forward.
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Attachments
d3.jpg
loaded round
d3.jpg (7.66 KiB) Viewed 962 times
d1.jpg
bolt pull back with the empty case
d1.jpg (8.26 KiB) Viewed 962 times
d2.jpg
Case ejected by the upward force from the new round below (magazine spring).
d2.jpg (8.79 KiB) Viewed 962 times

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Unread postAuthor: Blue Lagoon » Sun Sep 16, 2007 12:22 pm

btw this concept means that in idle mode the bolt is in open posistion and only closed when trigger is fully pressed and ignites with a piezo.

After releasing the trigger... the triggerspring will be powerfull enough to pull out the empty case. Maybe the the spring of the piezo ignitor will provide enough power... and then it's also figuring out the gears setup.
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Unread postAuthor: jackssmirkingrevenge » Sun Sep 16, 2007 12:29 pm

Ah, I was assuming you would be using the power of the cartridge to eject it by blowback, this was the design idea I was working with. I don't see why your idea shouldn't work, though as it is power is going to be on the disappointing side.

I'm still curious about your cartridge though, if you pump it up then it must contain pressure, how do you stop the BB from coming out? And how do you meter hairsray with sufficient accuracy for such a small volume?
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Unread postAuthor: Blue Lagoon » Mon Sep 17, 2007 7:08 pm

On the other end theres a rubber o-ring with a hole big enough to fit a 6mm bb airtight. I usually spray 1.5 sec in that hole first... wait about 40 seconds. Then i pump 4 times with a bicycle pump. No, it's not pressurized. After pumping fresh air i quickly close it with a bb.

fire, BWAM! Through a short test barrel.. enough to penetrate standard cardboard.

I'm planning to test weather the rounds can be fired after a long time.

I also have a problem with passing the spark trough the bolt to the round..
I have to think of a better and compact way to insulate. The bolt itself is fine but i found out that the metal o-ring is to close to the center pin... still conducting. There are thousands of ways to solve this problem.
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Unread postAuthor: FeLeX » Mon Sep 17, 2007 8:17 pm

Sorry dude but to me that sounds a big load of crap...
Theres no way combustion gun that big can shoot a bb through a cardboard.
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Unread postAuthor: Blue Lagoon » Tue Sep 18, 2007 1:55 pm

well... if you got enough oxygen/air,a good barrel and airtight fit. I've tried it many times. At first i didn't believe it too... I'm actually suprized it did go through.
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Unread postAuthor: jackssmirkingrevenge » Tue Sep 18, 2007 3:58 pm

it wouldn't hurt to post a video ;) I was disappointed with the power of my 6mm cartridge attempt, which is why I went for the 3/4" calibre
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