My very first piston cannon :)

[hyldgaard]

So, basicly i was inspired by the spudfiles coinchallenge to make a smaller diameter gun than i had tried before, with enough power to punch a dart through a coin. With some help on this forum i got pointed in the right direction and decided to go for a copper cannon with a 110cm 15mm barrel, with an ID of 13mm. My plan was to use a 1/2" or 3/4" qev, but due to the circumstances, i had to go with a homemade piston valve.
My thoughts on chamber was also copper, in a over/under construction, but the largest diamter copper i could get my hand on was 15mm, same as the barrel. And as i wanted a CB ratio a bit higher than 1:1 I had to figure something else out. The pop bottle is temporary till i get some 1" nipple pipe and the right fittings.
I use a blowgun for piloting, and i usually fire it at 85-90psi as thats the highest my dads compressor would go.
The unusual plug on the pilot tee is a replacement till i get a pressure gauge (borrowed one, but had to give it back after two days).
All in all not exactly the "final version" of this gun, but since i could only use my dads shop for one week, I had to put the parts together that I had
As a final note, this is my first pneumatic launcher so go easy on me
Well, enough talking, if you have any questions just ask.

[Marco321]

That looks like a good clean construction. Thats very nice gun i like it alot. Any chance of getting some pictures of the piston?

[hyldgaard]

sure thing, will be added to the original post in a couple of secs it's made from 18mm copper pipe, wich is a perfect fit inside a special fitting i put inside the valve tee (i dont know the name, but its the same as i used for the breech loading)
The picture however is not the piston in its final stage, but without the sealing face. The sealis made from a layer of very thick and double side sticky tape, and a layer of some other kind of very durable tape my dad had laying around

[Marco321]

Thats a nice looking piston, it will look great when it is complete.

[hyldgaard]

Yea i hope so, but unfortunately I wont be able to finish it before im visiting my parents again, which will be around christmas but hey, that gives me a lot of time to think about what i want done

[Marco321]

Oh ok thats unfortunate. Do you have the gun with you know? or is it left at your parents.

[hyldgaard]

Left at my parents. as you have probably noticed, i have no filling valve mounted except for the back of the blowgun, so it can only be filled with a compressor. But as a lot of other things, thats just a matter of time

[Marco321]

Left at my parents. as you have probably noticed, i have no filling valve mounted except for the back of the blowgun, so it can only be filled with a compressor. But as a lot of other things, thats just a matter of time

Oh ok i see. I'm looking forward to seeing it finished and many more of your guns

[hyldgaard]

I probably wont be doing a lot of guns, as i dont have the time or the tools/space myself. But i will keep you updated when i complete/add things to this gun.

[jackssmirkingrevenge]

Nicely done and after only limited advice, great stuff damage pics!

[hyldgaard]

Thank you very much i dont really get whats the big deal about the making of these piston valves, but maybe i was just lucky
i have a couple of damage pics on my mobile, will upload them later when i find my mobile>computer cable.
found a great way of making those darts btw, but i dont feel like using a lot of my time describing it if people doesnt care, youre welcome to ask for details

[ALIHISGREAT]

very nice darts and cannon but i would switch the coke bottle chamber for copper and pump it up to 200psi

[hyldgaard]

As said earlier, the camber will be changed next time i have acces to the gun. Though not to a copper one, as 15mm is the largest diameter pipe i have acces to.

[jackssmirkingrevenge]

i dont really get whats the big deal about the making of these piston valves

It really isn't that hard if you had the right materials, but many people seem to find the prospect of making your own valve as opposed to screwing in an off-the-shelf item to be rather daunting. Glad you weren't put off

How do you keep your darts stable in the barrel, as they're not supported from the front? Or do you just let them scrape along the sides of the barrel?

[hyldgaard]

I just let them scrape along the side of the barrel. My intention was to make some test darts with two sets of "fins" but never found the time.
Even though i just let them scrape, accuracy seems to bee fine. i didnt get to test it at distance due to lack of proper backstop, but at about 5 meters i was able to put 5 darts within a circle of 5 cm, with the very accurate "point and shoot" technique