Piston Air Rifle

some of you may have seen my first air rifle. quite basic, but as a shotgun it works quite well.

now i bring you my second air rifle!

unlike my first i will be providing (more or less) instructions on how to make your own.
Collaborating is enabled.

KEEP IN MIND!!
>>Air rifles are dangerous, they will Kill you if you give them a chance!! so be careful
>>Never look down the barrel! these rifles can go off at any time!!
>>Never aim at pets, thats just silly
>> i recommend thinking about safety while operating the rifle, when misused they have a tendency to explode! And the last thing you want is a piece of pvc lodged in your face...

so there i said it. now don’t come and blame me if anything should go wrong.
 

Step 1: Planning

i decided i will build another air rifle a while ago, since then i have been researching on the net about air rifles. i then started mind storming and drawing. i think i filled just over half a 96 page book with just ideas (most of which are crap...). i'm not saying you should do that much, but at least draw up a "not to scale" design of what your final product will look like. then you can decide what size parts you are going to need.

PLZ look at this site:

http://www.spudfiles.com/forums/piston-valves-explained-visually-t8157.html
it contains a break down on how a few valves work, i used a coax valve

Comments

[de0509]

I think its called "male threaded coupling". male and female can be determined by "if you know what i mean"

the coupling things are for joining two open pipe ends that are facing each other. maybe for in case you mis measured and cut the pipe too short, you can add a coupling and then join another pipe to make it longer

[chinnerz]

ah you are right, thanks for that.

However i should mention that i bumped my launcher and since the back where the threaded coupling was only plastic, it started leaking and misfiring, so i have disassembled the launcher so that no one hurts themselves.

So it is probably a good idea to reinforce this area with mouldable epoxy if you want to try it out.

[cowscankill]

I have made my coaxial almost exactly like this one, except with a resin piston instead of hotglue. Yet, the piston doesn't slam backwards like it should. All of the air comes out of the trigger. Any idea for help?

[chinnerz]

i am going to need some more information on your set up. do you think you can make a diagram of how it is set up and send it to me?

Also how did you make your piston, did you add some grease/ thick lube to your walls before you cast the resin? if not this could just be a case of your piston being too tight or too lose.

[cowscankill]

I asked some people on Spudfiles, they suggested that the piston is too small, but it's not visible to the naked eye.
I wrapped one layer of teflon and managed to get some feedback, but now I am trying to get an o-ring on my piston in order to make it tighter.

[chinnerz]

yes, that could very well be the issue, when you shake you launcher do you feel the piston move?

i have attached an image of a really good piston design, this will work only if you fill form behind the piston..

key:
black------piston
maroon--O rings
blue-------Cavity/ hollow tube
red--------One way or check valve.

You could also try casting the piston from a different resin, maybe this one shrinks a little when it is fully cured.

[cowscankill]

Haha, it's cool how I found out that design too, just slightly modified.
For now I use a hotglue piston, though it is very small and I can't get the sealing face to stay attached. It works well now and the gun can shoot a pen through boxes, but the 1" threaded plug I am using on the back of the chamber won't seal. It's a royal pain. I've wrapped it in * layers of teflon tape, maybe it needs more...

[chinnerz]

A really easy way to attach the sealing face is to simply nail it in, making sure to flood the place with araldite so that when it sets, it is 100% in place and air tight.

As you are using hot glue, i will offer this advice.
>Never leave your launcher in direct sunlight,

>As soon as you detect an air leak, remake your piston.. its cheap and easy.. launching a pen into your leg due to a misfire isn't.

>If you don't use your launcher for a month or 2, you will need to pull it apart and lube it up with a plastic safe lube.

always use a strong back board and if you aim at wildlife, you're a twat.
Good luck with your future endeavours in this hobby :)

oh yeah, be sure to stay tuned, around the end of the year i will unveil number 3 :)

[cowscankill]

Never thought of that, thanks! I'll subscribe so I can see what you post :D
I will probably just post videos or photos of the completed gun. It's going to be a dual wield twin gun combo, and possibly a cannon if it'll work.

[chinnerz]

Awesome!, looks like i'll be subscribing to you too :)

[josh333]

 Awesome ibbble....Do you have a vid?

[chinnerz]

yeah im just working out a few things with the gun, right now it lies in pieces on the floor. i was going to add an in built silencer...... o wait i dont have any pictures on this site of the finished stock and paint job..... hmm. ill add a target shooting vid will be next week maybe (as it is raining right now)... school is keepen me busy atm, (sigh yr 12 sucks) 
ill pm you josh when i have added it.

In the meantime check out the stock and paint job on this site: http://www.spudfiles.com/forums/simple-co-ax-with-attached-stock-t20115.html

 

[meddler]

Simple, effective, and spot on. Bravo mate!

[lemminggenocide]

it's criminal that so few people hve seen this! great job!

[chinnerz]

thanks mate :D made my day with that comment.