SpudFiles

Hi there.

Although this is not the first cannon i ever built, the other two were the manual chamber-ballvalve-barrel type. Which was fun for a while, but this is my first more "advanced" attempt at this And English is not my native language, so i hope my writing isn't too bad


My main goals were to keep it portable, simple, affordable and easy on the eyes


The 3/4 QEV was the most expensive part, but the hardest parts were the two elbow-ish pieces (Getting them to fit perfectly) that are responsible for the very neat alignment of the barrel and chamber, its hard too see on the pictures, but they barely touch. The gun is filled through the quick disconnect on the back.


The pilot valve was recovered from an old powder extinguisher, it vents the pilot air quickly (Enough.. I think) AND it came with a very nice little pressure gauge


I use an HPA rig with a makeshift adapter to fill her up Unfortunately, i use the rig for a few airsoft guns i own, so it was never meant for high pressure. The gauge only goes to about 16 bar, whilst i intent to run the cannon at 20 bar... And i don't wanna risk breaking the gauge.


The barrel is an aluminum profile tube, screwed (With some effort...) into a fancy looking 3/4 union fitting. Because of the limited pressure and the fact that i still need to solve a slight leak, means that i haven't really had time to test ammo. But i plan to use homemade candle wax slugs with a steel penetrator inside of them.

I already tried this once and was pleased with the results A co² cartridge (Not 12g but just a tad bigger) fits inside the barrel PERFECTLY! But i only have ONE of those lying around


And i also made a rifle grenade for it out of boredom Its incredibly fun to launch in the backyard and makes a great "thump!" when you shoot it^^


The fit of the grenade on the barrel is perfect IMO especially because it was a pure coincidence! The fit is so tight that if you move the grenade up and down on the barrel whilst keeping the pilot valve open, you can hear the QEV opening and closing That is, if the cannon isn't pressurized of course :p

BUT UNFORTUNATELY: When i was taking these pictures today, the cannon fell on the ground with the grenade attached to it... Result, a few fins broke of and i'm not sure if i want to fix em again since getting them glued on in the first place was tricky as hell.

Anyway, i hope you guys like my first "decent" creation Feel free to say what you think about it or to ask questions!

Greets.

Nice, love the all metal construction and the grenade is a nice touch.

On the other hand, you can't present an HPA cannon without damage pics/videos, this looks like it's pretty destructive

<s>Hot tip: If a CO₂ cartridge fits, so does a 12 bore shotgun wad </s>

Edit: nevermind, thought it was a 12 gram, looks like the one you have is a 16 gram.

Great job dude! That thing is nice!! Pilot volume's a bit large but that's alright if it works!

VERY NICE!! And welcome to Spudfiles!

That looks great, I like the pilot valve! Welcome to Spudfiles!

Looks solid and I like the look of the fire extinguisher valve for the pilot. Fire off some 12 gauge shotgun wads with random steel junk and film it for posterity.

Thanks for all the nice replies! I have a picture of the CO² cartridge compared to a normal 12g cartridge:


As you can see, its a nice fit

And i found a damage pic for you guys, its the one candle wax with penetrator round i tested, note that this was not fired at full pressure


The "smudge" you see around the hole is from the candle wax expanding when it hit the target, the actual hole is from the steel insert



@Gun Freak: I was indeed a little worried about the pilot volume at first, but a soon as i squeeze the valve it just goes bang! I don't have the feeling that something is wrong or not working correctly But on the other hand, this is my first QEV cannon, and i reckon that you have alot more experience whit these thing then i do

Awesome build! How's the fire extinguisher pilot valve working for you? You could try a 1/2" ball valve just to see if it increases performance much. My dry powder fire extinguisher had reasonably poor flow but yours may be different. You could also minimize the pilot volume and keep the fire extinguisher valve.

If you measure the port of the fire extinguisher you can model the performance of the cannon using GGDT:
http://www.thehalls-in-bfe.com/GGDT/

Actually I've never used a QEV
As long as there isn't a noticable delay between triggering and firing, you should be good.

Hmm i can't really guess the size of the port just by looking at it, but maybe this pic will help to make an estimate:

Looks like about a 1/2" diameter, but that doesn't mean the valve stem port is 1/2" also. It is probably 1/4" to 3/8", I'd guess.

Well like i said, when i open the valve it just goes boom I can't seem to hear any noticeable delay when shooting it, unless i open it slowly. Its pretty much like pulling the trigger on a rifle. Not squeezing it of course

Very nice looking cannon.
Looks very clean and a well thought out design overall,
The Trigger/gauge is a nice touch in my opinion.

Not to mention the HPA supply source, awesome...

Alex345 wrote:Well like i said, when i open the valve it just goes boom I can't seem to hear any noticeable delay when shooting it, unless i open it slowly. Its pretty much like pulling the trigger on a rifle. Not squeezing it of course

Do you hear any air leaving the cannon directly after the shot?

jrrdw wrote:Do you hear any air leaving the cannon directly after the shot?

Nope, unless i keep the HPA rig connected between shots because it will keep supplying air