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Another Barrel Sealer

Posted: Sat Apr 25, 2009 7:47 am
by Mogwog
Firstly, I'm a new user to this site and I've been looking around on it for help on how to go about just building a stock standard barrel sealer as my first proper cannon. I just have to say that it was very helpful to be able to see such a range of designs and discussions on them and that this is by far the best spudding site that I've seen.

And now for the interesting bits:

My Cannon, in all its primer and glue stained glory

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All of the pipe is PN12-PN18 (which means that it is rated to at least 170psi) but I usually only go up to about 120psi just to be on the safe side and also to try to preserve my piston from damage. It's got an advanced ball valve as the pilot valve and the piston seals on a 4cm diameter section of pipe. It is also quite ergonomic (for left handed people) because you can push your shoulder into the "t" and let it sit over your shoulder with very little effort and from there you can easily reach the trigger.

The whole trigger mechanism looks pretty flimsy and I know that I've used dreaded Zip Ties to tie it on but I really can't be bothered to do it properly so for now I will say that it is for easy disassembly. To actuate the ball valve, it has a spring and some rubber bands to pull on a length of fishing line.

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The piston is also pretty ghetto because it was made out of the lid of a spray can and some fibreglass. To make sure that the lid doesn't blow out under pressure, the fibreglass extends into the inside of the lid to reinforce it.

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As part of the bumper for the piston I've shoved a bit of foam into the piston and inside the cannon there is some more cushioning.


Here it is with its golf ball barrel on. It also has a marble barrel and slightly bigger sized one for miscellaneous projectiles.

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Here are some fake golf balls that I made from a mould of a golf ball and glued together with some of the leftover fibreglass resin. The one on the right looks a bit different because I decided to spread some resin around it to make sure it doesn't disintegrate in the barrel because, for some strange reason, lots of things tend to disintegrate in the barrel....

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Well that's pretty much it for now untill I can get some damage pics and for that to happen I'm going to need to find some more golf balls and marbles to fire which might take a while.

Posted: Sat Apr 25, 2009 3:03 pm
by Sparkie
Now that is an awesome looking weapon.
I started with a modded valve for my first shooter.
But you went straight into rapid release piston actuated nirvana.
How is the accuracy and power?
Now that you are hooked like I am a semi automatic sniper rifle is only a dream away.

Well done and if you can, some damage pics could be nice.

Posted: Sat Apr 25, 2009 6:18 pm
by Mitchza89
Fantastic job on your first gun Mogwog. I really don't have much else to say but that. Keep the guns coming mate and welcome to Spudfiles :)

Posted: Sat Apr 25, 2009 8:35 pm
by covey12
do you have red and green primer?

Posted: Sat Apr 25, 2009 8:52 pm
by Gaderelguitarist
That looks more like pink and green primer :wink:

Not a bad first. Its good to know that you've at least done your research on the forum.

Interesting idea for ammo. I don't know that anyone has thought to cast golf balls.

Posted: Sat Apr 25, 2009 9:45 pm
by Mogwog
hey sparkie, the accuracy isn't so good because golf balls and marbles tend to spin off in odd directions sometimes but the power is really good and the recoil with a golf ball at 120psi is kinda scary when your not ready for it.

covey12, I actually had white and red primer and blue and green glue so thats why it looks a bit like I spilt paint all over it. Btw do you think that i should paint it? If so what kind of paint should I use?

Posted: Sat Apr 25, 2009 9:51 pm
by jmeyer1022
Paint it to a color of your liking, use krylon fusion paint its for plastics. Great cannon by the way keep it up.

Posted: Sat Apr 25, 2009 10:00 pm
by Technician1002
Great cannon. :) To prevent piston breakage, flat surfaces for the bumper tend to be better because sometimes the foam can get packed inside and then provide no cushion. To keep the piston weight down, I tend to put all the bumper in the back of the pilot space instead of having it ride on the moving part.

Fastening the chamber to the barrel is a good idea so recoil doesn't cause any joints to fail.

Posted: Sat Apr 25, 2009 10:37 pm
by Mogwog
Thanks for that Technician, The chamber does have some sections of some stubbie holders in it but I thought it needed a bit more cushioning. As for the piston itself, I think that I will have to glass over the back of the piston to give it a bit more area for the force of the collision with the bumper to disperse on.

Also, wouldn't fastening the barrel to the chamber mean that I would loose the ability to repair the piston and bumper inside the chamber? I Think that I'm going to need to leave the barrel as a screw on attachment to the chamber. Definitly next time I will take your advice and I will make the back of the chamber able to screw off instead of the front.

Posted: Sat Apr 25, 2009 10:53 pm
by Sparkie
Mogwog wrote:Thanks for that Technician, The chamber does have some sections of some stubbie holders in it but I thought it needed a bit more cushioning. As for the piston itself, I think that I will have to glass over the back of the piston to give it a bit more area for the force of the collision with the bumper to disperse on.

Also, wouldn't fastening the barrel to the chamber mean that I would loose the ability to repair the piston and bumper inside the chamber? I Think that I'm going to need to leave the barrel as a screw on attachment to the chamber. Definitly next time I will take your advice and I will make the back of the chamber able to screw off instead of the front.


Another Aussie on the forums from the sound of it.
Welcome to Spudfiles from sunny Queensland....Spud shooters paradise...except for the silly laws about Spud guns!

Posted: Sat Apr 25, 2009 11:45 pm
by Mogwog
Yup you guessed it I'm actually from Queensland too. It was really hard to persuade my dad to let me put the stubbie holders to a better use but I eventually won him over. Shame about the laws though, I usually disassemble it and then take it into a big patch of bush right next to my house so that no one can hear it.

Posted: Sat Apr 25, 2009 11:46 pm
by Crna Legija
Also, wouldn't fastening the barrel to the chamber mean that I would loose the ability to repair the piston and bumper inside the chamber? I Think that I'm going to need to leave the barrel as a screw on attachment to the chamber. Definitly next time I will take your advice and I will make the back of the chamber able to screw off instead of the front

fastening the barrel to the chamber is a good idea. dont glue it just use a peace of wood to stop the barrel bending and tape the barrel to the chamber or use cable ties

Posted: Sat Apr 25, 2009 11:56 pm
by inonickname
Very good! You've clearly done your research and have skills and applied it into making a powerful, cool cannon.

You could still fasten the barrel to the chamber without making it permanent.

Posted: Sun Apr 26, 2009 1:24 am
by Mogwog
Thanks for the tips inonickname and -_-, I think i will fasten the barrel to the chamber before I get those Damage pics because I don't want my cannon to break (or explode) due to the stress of the recoil.

Posted: Sun Apr 26, 2009 2:21 am
by inonickname
Yep. You could use a block of wood or plastic between barrel/chamber then fasten it with hose (radiator) clamps, string, tape, wire..anything.

Or for a more permanent fixation you could make a mold and cast it in some bondo body filler.