Homemade Mini Coaxial Airgun

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Homemade Mini Coaxial Airgun by bigbob12345 on May 24, 2008

Table of Contents intro: Homemade Mini Coaxial Airgun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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step 1: Getting Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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step 2: Putting parts together . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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step 3: The barrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

step 4: Finding the right size chamber and cutting it. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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step 5: Piston . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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step 6: Cementing the pvc together . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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step 7: Have fun with it . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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http://www.instructables.com/id/Homemade-Mini-Coaxial-Airgun/

intro: Homemade Mini Coaxial Airgun Well this is my instructable for my coaxial airgun that I put together. It costs about $15 to construct, and is very fun to mess around with. It shoots at roughly 600fps+ at 120psi with a .12gram airsoft bb and the excact specifications of the airgun made in this instructable. And I must state that ***IT IS NOT MY FAULT IF YOU OR OTHERS ARE HURT OR KILLED AS A RESULT OF THIS AIRGUN*** And a couple tips (pretty much follow them or you will die,no joke) *Never pressurize it over 140psi, even though it says rated to 480psi on the side. *Never look down the barrel, even when you dont think it is loaded or pressurized *Never aim at anything you do not intend to destroy *Do not use this in an airsoft war, this is meant to just be something to mess around with. It will penetrated human flesh. *Give the pvc cement and epoxy a full 24 hours to dry, no less. *Have fun Make sure you understand all those tips before going to next page. And if you dont understand how a piston valve works then this is a helpful link.

Image Notes 1. The completed airgun

step 1: Getting Parts Well go to some hardware store and aquire all thse parts 1x 1/4in ball valve(metal) 2x 3/4in to 1/2in bushings(metal) 2x 3/4in female adapter(pvc) 1x length of 3/4in pipe of the desired size(pvc) 1x 1/2in copper cap 1x 6mm brass or aluminum tube of the desired length(might not be avaiable at your hardware store, try a hobby shop) 2x 1/2in to 1/4in bushing(metal) 1x 1/4in NPT schrader valve 3x 1/4in close nipples(prefferabley brass over steel) 1x double syringe container of epoxy whatever tape strikes your fancy bike inner tube And some tools that you most likely have but if you dont you need to get them. Scissors Clamp Adjustable wrench Pipe wrench A vice is helpful but not nesessary A nail(or similar) And that is it If you dont have some of tools the project will be a lot more pricey.


Image Notes 1. Some 3/4in sch40 pipe 2. 1/4in ball valve 3. 1/4in tee 4. 1/4in nipple, 2 brass, 2 steel 5. 2 1/2in to 1/4in bushings 6. 2 3/4in female adaptors with 2 3/4in to 1/2in adaptors already screwed in 7. 1/2in copper cap 8. teflon tape 9. inner tube from a bike tire 10. various wrenches 11. There are quite a few of the nessesary materials missing from this picture.

step 2: Putting parts together Time to thread some of the parts together. Make sure to add atleast 4 layers of Teflon tape to each joint before threading it in. Take your 3/4in female adaptor(pvc) and thread your 3/4in to 1/2in bushing into it. Make sure not to overtighten here, you don't want to crack the pvc. Next take your 1/2in to 1/4in bushing and thread it into the 3/4in to 1/2in bushing. Tighten this one as hard as you can, you don't need to worry about cracking the metal that much. And then repeat what you did with your first female adaptor with the second female adaptor. Then with the second female adaptor thread a 1/4in nipple into the 1/2in to 1/4in bushing. Then thread a 1/4in tee to that. Thread a 1/4in nipple to one side of the tee and a schrader valve to the other side. Then thread the 1/4in ball valve to the 1/4in nipple. And thats it for now

Image Notes 1. Threading the 3/4in to 1/2in bushing into the 3/4in female adapter.


Image Notes 1. Never thread in any more than this otherwise it could possibly crack.

Image Notes 1. Needs to be tightened down farther

Image Notes 1. What the second female adaptor should look like after threading everything to it

Image Notes 1. What you have completed by now.

step 3: The barrel Well you are going to need to epoxy the barrel to a 1/4in brass nipple in orded to attatch it to the gun. Video of how to do that right here. http://www.youtube.com/watch?v=7CUGqOPiQSw I recommend you click on high quality at the bottom. Next I would reccomend you clamp it in a vice for an hour or so but if you don have a vice then you are going to have to just hold it in your hand steady for about 20min and then set it down for another hour or so. After that hour wait for it to partially dry you can screw it into the 1/2in to 1/4in bushing on that 3/4in female adaptor you put aside. Remember to teflon tape it.


Image Notes 1. before it was epoxyed on

Image Notes 1. Clamped in a vice after epoxying and waiting for it to dry.

Image Notes 1. Screwed in the 1/2in to 1/4in bushing

Image Notes 1. Sticking out the other side of the female adaptor.

step 4: Finding the right size chamber and cutting it. Well since your barrel is probably a different length then mine you are going to need to find a good chamber length for your barrel length. Compare the length of your barrel to your chamber and then about 1in farther down make a mark with a pencil or pen. This is where you will cut with a hacksaw. Next you cut at the mark you made trying to keep it as sqaure as possible. If you want you could you a mitre box but I dont assume that to be nessesary. After you have made the cut smoothen it with course sandpaper. And you have your chamber.


Image Notes 1. I marked a little too far down as you can see.

Image Notes 1. Sanding the cut end to smoothen it.

Image Notes 1. the sanded end

step 5: Piston The piston is rather simple to make. Just take your copper cap and epoxy some inner tube cut to size onto the top. Use the same epoxying technique as when you epoxied on the barrel. Then wrap the cap in your choice of tape until it fits well but slides easy in the 3/4in pipe. Thats it, you piston is done. Of course you don't need to use a copper cap for the piston. There are much better piston materials out there, such as a casted epoxy piston. Its just the copper cap is very easy and reliable(I've shot it more 300 times without a single problem). And sorry I have no pics.

step 6: Cementing the pvc together Well now its time for you to cement the pvc together If youy have never solvent welded before I recommend you seek advice from a plumber. But if you dont feel like doing that then you can always just read this. Prime one of the 3/4in female adaptors and prime the end of the pvc pipe. The add some cement on both surfaces and push it together. Hold it together for 30sec. Then do the same to the other female adaptor and end of the pipe. Leave it for 24hrs to dry Once it done drying your gun is complete.


step 7: Have fun with it Once you are done waiting for the glue and epoxy to dry all you need to do is unthread the 3/4in to 1/2in adaptor out of the female adaptor and pop in your piston. Rethread the 3/4in to 1/2in bushing and your set. Charge it up to whatever pressure you like(under 140psi) And unleash by opening the ball valve. http://www.youtube.com/watch?v=19ROhC86BmA Remember all the safety rules stated at the beginning.

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Comments 19 comments Add Comment

joejoerowley says:

May 29, 2008. 4:42 PM REPLY Very Cool! Great Instructable! Looks LIke a great gun. Now just make a hopper and loader for it and strap a CO2 tank to it and you have the most bad ass gun ever! Well done!

bob the builder #1 says:

Dec 19, 2008. 3:33 PM REPLY

learn what a coaxial is, then you'll understand why you can't add a hoppper

clemsonguy1125 says:

Oct 18, 2008. 4:28 PM REPLY

do you have to repump it every time you want to fire it

bob the builder #1 says: yes


Dec 19, 2008. 3:31 PM REPLY

evanwehrer says:

Oct 3, 2008. 10:57 AM REPLY This is really cool, when i make mine, I'm gonna use the air can from this instructable. And I may find an electric valve if I can find one wit the right size. (Ill try to post pictures)

thebluemartyr says:

Sep 15, 2008. 2:28 PM REPLY

why did you remove all of your videos??

bigbob12345 says:

Oct 1, 2008. 6:04 PM REPLY i didnt, my computor got hacked by some idiot and he got hold of some of my passwords, he then proceeded to mess up some of my accounts, including deleting my youtube account.

aerophyte says:

Sep 22, 2008. 12:23 PM REPLY

Can you please post a video shooting the airsoft ammo and then one shooting liquid (loaded after pressure us applied)? Thanks!

henrywfstone says:

Sep 18, 2008. 2:51 PM REPLY

from what i can tell this looks great! but i have no idea how to make it. NEED DIAGRAMS !!!!!!!! i REALLY REALLY want to make this! :P it would be perfect for my physics project (im designing body armour)

Mattrox says:

Jun 1, 2008. 10:22 PM REPLY

great work very helpfull 3.5 rating

Mattrox says:

May 31, 2008. 7:34 PM REPLY

how does the firing system work im stumped

bigbob12345 says:

Jun 1, 2008. 6:54 AM REPLY Well there is a piston and you fill the air in behind it. This makes it move forward and seal against the barrel. And when you exhaust the air behind it with the 1/4in ball valve the air infront of it pushes it back very fast and goes out the barrel. I probably should have included some animation in it. If I get the time I will make one but if not I'll just add a link to something helpful

Mattrox says:

Jun 1, 2008. 1:45 PM REPLY

thanks

bigbob12345 says:

Jun 1, 2008. 2:01 PM REPLY

Well I didnt get the chance to make a animation so I just posted a link to an animation made by someone else. Hope it helps you understand it.

Mattrox says:

May 31, 2008. 5:16 PM REPLY

awesome bigbob12345 but could you add some boxes naming the parts pleaz

bigbob12345 says:

May 31, 2008. 6:59 PM REPLY

I'll do that right now

Mattrox says:

May 31, 2008. 7:31 PM REPLY

cool looks great

pyroelectro says:

May 30, 2008. 4:09 AM REPLY

nice one mate in the intro at the end of the list of things to 'pretty much follow or you will die' you said have fun...haha 'have fun or you will die' i like it!!


Sgt.Waffles says: Sick as! Good on ya!


May 29, 2008. 8:34 PM REPLY

Homemade Mini Coaxial Airgun

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