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Preloaded Cartridge Prototype

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: Davidvaini » Mon Sep 01, 2008 11:48 am

its okay about the necro post.. a lot of people are using my design these days, its good to ask questions.

I use genuine innovations co2 inflator.
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Unread postAuthor: ROB » Sun Sep 28, 2008 7:05 pm

Its a good idea but...


I don't know were the hell you got this foil tape idea from,or what type your using. Is it super thick or somthing?

cuz I just tryed this today and the foil tape was worthless...I did find other things that worked well.

I know it worked for you. It just don't know what is wrong with my foil tape....


also....whats the best projectile you have used, because I used a golfball and it did not work well at all. Does it have to be super light or somthing because in the video you seem to use a foam ball.
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Unread postAuthor: Lentamentalisk » Sun Sep 28, 2008 7:17 pm

well he has used light stuff because the large diameters and short barrels will do very little for something heavy. Most GB cannons have 3'-5' long barrels, and run on 100psi or more. I dont remember David ever making a barrel more than 1' long, an I remember him saying the max pressure he got was around 60psi. There is no way in hell a golf ball will go anywhere with those specs. That is why he uses it for airsoft.
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Unread postAuthor: ROB » Sun Sep 28, 2008 8:05 pm

still I shot very light items, and the foil tape was still blowing out before any pressure was built up.....so Idk.


I know I am not getting any pressure...because I put my hand in front of a dry shell with the foil tape , and it felt like calm day on a beach. Then I did it again...(with diffrent meterial) and it was like a damn hurricane.

so theres obviously a problem with my foil tape....
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Unread postAuthor: Lentamentalisk » Sun Sep 28, 2008 8:13 pm

did the tape actually burst, like you see in all of the pictures of spent burst disks? or did it just come undone and leak around the edges. If it is just leaking out, then you aren't getting it held in there well enough.

@Mc Carl: changing the color of your text doesn't make us reply any faster. Maybe, if you had spent the time it took you to change the color, actually giving us information as to what specifically you tried we could help you. Saying that it doesn't work is a direct lie, and accusing a reputable member of "photoshopping" their video for the detriment of our hobby. What you actually meant was that you failed to implement his idea properly, and would he now ever so kindly help you out to troubleshoot the problems, good sirs.
[/rant]

edit:
oh, and can we have a mod ban him or something?
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Unread postAuthor: ROB » Sun Sep 28, 2008 8:18 pm

ya it blows out ....it just don't get the same results as he does...Idk why.
I understand it could be the projectile but they work when I use other burst-disk meterial.


Note: I made it the same as his 1- 1/4 shell so...
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Unread postAuthor: Lentamentalisk » Sun Sep 28, 2008 8:22 pm

so you get a circular rip in the center? or does it leak out one side, around the edges. If the latter is true, then you need to work on finding a way to get it to seal better. If it is rupturing in the middle, like it should, but just not giving you any pressure buildup before hand, then try adding more layers of tape.
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Unread postAuthor: ROB » Sun Sep 28, 2008 8:29 pm

ya, it blows a circular rip out.... theres just no pressure to speak of.

In the video(s) it shows him putting only 1 layer on. And it makes a very load bang. Then I try and its more like a (puff)

I got it to work dont get me wrong (with other meterials) Im just curious as to how he got his to work that way (with only 1layer of tape).
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Unread postAuthor: Lentamentalisk » Sun Sep 28, 2008 8:32 pm

he probably has a thicker variety of tape than you do. I would just pile up the layers. Beyond that I don't really know that there is anything for you to do, other than stick with your other materials.
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Unread postAuthor: ROB » Sun Sep 28, 2008 8:38 pm

Ill just keep messing with it.






thanks for the help.[/quote]
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Unread postAuthor: Davidvaini » Mon Sep 29, 2008 12:02 am

Standard foil tape used for heating ducts is the type I use.

Either you are putting the foil tape on incorrectly.. (please see my video on how to apply the tape.)

This idea does work and its been tested by me, several of my friends as well as other reputable members on this forum. It is used to fire bb showers/ nerf ballistic balls. I have fired a golf ball out these shells but with the low volume of the air chamber Its obviously not gonna shoot extremely far.

Even at low pressures you should be getting a loud bang. The only time you get a puff or a quiet shot is when the tape was incorectly seated on the pipe.

I would suggest sanding down the end of the pipe to make a smoother surface. The foil tape should mushroom out after you have fired. Anything other than a mushroom is simply a dud.

Two of the following issues could be attributed to your failures.

* Extremely bad foil tape (the stuff I use is off brand stuff)
* Incorrect seating.

When attaching the coupling, please make sure to not wiggle back and fourth as this will cause premature tearing. Premature tearing will result in a weak burst. The noise of the shot when you have a premature tearing will sound like "psssst". When you actually get a good seal it will sound loud and you will know it fired correctly.

Its really not hard to get a good seal.. biggest tip is to sand down the pipe and its edges so they are not as sharp.



Can the mods delete the posts by mcarl and related posts?
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Unread postAuthor: Davidvaini » Tue Sep 30, 2008 2:32 pm

Thanks to the mods for deleting the posts made by mcarl.

I also hope that ROB has figured out the problems that he was running into.
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Unread postAuthor: ROB » Thu Oct 02, 2008 6:50 pm

I did thank you... :o
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Unread postAuthor: Davidvaini » Sun Oct 05, 2008 3:10 pm

Sure, If anyone ever needs help with my designs I will always try to help.
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Unread postAuthor: newbmatic » Sun Oct 05, 2008 4:55 pm

Hey, i was just wondering how do you get your coupler of your chamber after you have fired it? Cause unfortunately my coupler wont come off. Thanks in advance. o btw awesome design.
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