SpudFiles

So this is my first big cannon project and I actually like it more than my second. and btw what do you guys think I should call it? It is a 1/2 inch coaxial piston valve cannon. The best part is it's shoulder fired, bazooka style!:lol: Here it is:



Specs:

length: 6'
barrel: 1/2 inch pvc
chamber: 2inch pvc
main valve: piston valve
pilot: 1 inch electric operation sprinkler valve
average operating pressure: 50 psi
max pressure: 120 psi

The trigger is a from a hacked toy and and is very erganomic:



The pilot and ultra ghetto battery pack :





It can hook up to a compressor or bike pump thanks to the adaptor:



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a sweet water balloon shot:
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I also added some neodium magnets at the breech of the barrel so it holds my favorite ammo(steel Magnetix balls) stronger. Now I can move the gun around without the balls rolling out

You should put a blow gun on your sprinkler valve, much better opening time

DANG! That thing is a beast! Nice job, pneumatically mod the sprinkler valve, though. But man that thing is huge. Cool!

Edit, your front coupling is DWV, not pressure rated. You can tell because the bushing barely goes in.

Very cool cannon dude!I like the bazooka style shoulder style shooting!! If you want better results, definatly mod that sprinkler valve. You will see a HUGE difference!! Also, as gun freak noticed, that coupling is dwv, so be careful. Its a easy fix if you wanna fix it. Other than that, good job!! Congrats!!!

If you want about 4X the power from the same size package, build your next one with a 1 inch barrel. See my Mouse Musket for assembly info. The Chamber Barrel ratio for a 1 inch barrel and 2 inch chamber is about 1:1. The chamber space will look small, but when you do the math for the volume, it works out. Very nice build. Lots of power. Long barrel should work well with heavier projectiles such as AA batteries.

Well done.

For future reference, it is generally a good idea to put the fill fitting through a double layer of pipe for strength such as in the threaded adapter for the sprinkler valve instead of through a single layer such as into the side of the pipe. That weakens the pipe and the chance of a broken pipe is high.

Mouse Musket info is in my sig below.

Next summer I think Im going to replace the coupling and in the process, also make it compatible with other barels. Thanks u guys for telling me about the dwv coupling but I think I should be safe for now since I only go up to 50 psi and It is only a 2 inch coupler(not so much force on it compared to a 4 inch for example)

pneumaticcannons i have a quick Q and for anybody who might know i just tried building a co-axial and i used 2 inch barrel 3 inch chamber pvc bout 3 feet long.. problem i ran into is my barrel is not perfictly centered wat can i do to center my barrel inside the chamber
ps i cant post pictures no camera at all

cannon monkey wrote:pneumaticcannons i have a quick Q and for anybody who might know i just tried building a co-axial and i used 2 inch barrel 3 inch chamber pvc bout 3 feet long.. problem i ran into is my barrel is not perfictly centered wat can i do to center my barrel inside the chamber
ps i cant post pictures no camera at all

try using bits of pvc pipe as I did to hold the barrel in the center, hope this helps!

I used short pieces of poly tubing zip tied to the barrel on my Mouse Musket. I drilled holes in them so they would lay lengthwise the barrel for flow when zip tied down, spaced them evenly, and zip tied them in place about 6 inches from the breech. They squish down slightly fitting inside the larger pipe and center the barrel perfectly. Since they are not metal, they will never rust out.

People have asked this several times. I'll plan on making up a dummy barrrel and chamber to show it in pictures. I'm not taking apart a cannon to get photos..

Nicely done, the electronic trigger makes positioning a bazooka-style trigger a piece of cake.

If you want better results, definatly mod that sprinkler valve. You will see a HUGE difference!

I would leave it as it is, as the sprinkler valve is the pilot and not the main valve, there likely would not be a lot of performance benefit gained by modding it in this case, definitely nothing that would outweigh the convenience of an electronic trigger.

jsefcik wrote:You should put a blow gun on your sprinkler valve, much better opening time

I don't think modding it will increase performance too much and the difficulties involved in triggering the valve from a behind me would deem the cannon overcomplicated

cannon monkey wrote:pneumaticcannons i have a quick Q and for anybody who might know i just tried building a co-axial and i used 2 inch barrel 3 inch chamber pvc bout 3 feet long.. problem i ran into is my barrel is not perfictly centered wat can i do to center my barrel inside the chamber
ps i cant post pictures no camera at all

I would actually use tecnichians method if u want to use changeble barrels

Edit by jrrdw, double posting.

shoulder mounters are dangerous!
nice gun, I admire that you have a giant chambre and a tiny barrel.
Does the mini barrel make loading easier than a large barrel?
you should build a handle of some sort to take away the danger of blowing something up next to your face.

qwerty* wrote:shoulder mounters are dangerous!
nice gun, I admire that you have a giant chambre and a tiny barrel.
Does the mini barrel make loading easier than a large barrel?
you should build a handle of some sort to take away the danger of blowing something up next to your face.

If it were t blow up, it would be on the ground while I was pressurizing it. Also the first thing to go would defiantly not be the pipe itself. I promise you it's perfectly safe to shoot

pneumaticcannons wrote:If it were t blow up, it would be on the ground while I was pressurizing it

Not entirely true you do put more stress picking it up so if there was a hair line fracture it could just give way when you lift it up, unlikely but possible

also firing it the piston could blow out the back, and the front coupling is ether DWV or the reducer is not fully seated.

I approve of this cannon. it would look SICK painted flat green.
Normally i'm not a fan of electrically actuated sprinkler valve... but i LOVE the trigger that you have.

Just to point out... It looks like ALL the fitting are DWV. (except the front bushing.)

I would advise on your next build, yo make sure you get pressure rated fittings... they have a much deeper socket. the couplers are about 2x as long.

I personally, WOULD shoot this at 50psi.... but if you ever hear even a tiny leak from any of the fittings... set it down very carefully and GET the #%@& away from it.

when you build your next one, use pressure rated fitting, and crank her up to 150 psi. (also, use a 1.5'' chamber with a 1/2 barrel... 2'' is nice, but overkill. you would notice very little performance decrease.)