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Picture of Mini air-powered pen gun
How to make a small pneumatic gun out of a pen. It can be pressurized over 100 psi and shoot small nails into wood. THIS IS DANGEROUS if you choose to make this I am in no way responsible if you injure your self shooting it or if it explodes while your pressurizing it.

*I didn't know this but someone has already done a better job of a pneumatic pen on spudfiles http://www.spudfiles.com/forums/pneumatic-pen-gun-project-t7858.html thanks to Surfguy21 for this info
 
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Step 1: Parts

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For this project you will need a bic pen and another piece of tubing (I got mine from a mechanical pencil) that fits inside the front peice of the bic pen if you remove the ink cartrige. You will also need a Zebra mini mechanical pencil (got from staples) or an eraser that fits inside a bic pen and you can drill a hole through. You need a schrader valve (the ones used on bike tires), and a airsoft bb.

Step 2: Tools

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All you need for this is a knife and some epoxy.

Step 3: Get the schrader valve

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The best way to do this is to get an old bike innertube and cut the schrader valve out, then sand off about 3/8 of an inch of the rubber off exposing the brass.

Step 4: Taking apart the pen

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This is really simple just disassemble the Bic pen and keep all the parts.

Step 5: Prepare the eraser

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All you need the Zebra pencil for is its eraser and spring. The spring is pretty self explanatory, just bust apart the pencil and take the spring out. The eraser will serve as a seal it will go on the end of the larger tube (not the ink cartridge) and be sealed when the airsoft BB touches it. In the drawings pink is the eraser.

Step 6: Prepare the end cap

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This step is a lot like the eraser step just cut off the end cap of the pen so you end up with a plastic tube.This is the black part in the middle of the drawing.

Step 7: Assemble the valve

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In this step you combine all the parts you have been preparing. Get the large tube insert it into the end piece of the Bic pen and epoxy it. Then place the eraser doughnut over the other end so that some of the eraser is sticking out past the plastic tube, then epoxy that in place.

Step 8: Make the piston

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This is very simple, just glue the airsoft BB onto the end of the Bic pen end cap(this may need to be sanded so it slides easily inside of the pen tube, it shouldn't be airtight so feel free to sand lots off) and then glue a spring inside of that. See pictures for detail.

Step 9: Make the barrel

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The barrel is just the ink tube that has been emptied of ink. Use some wire and a small piece of cotton to clear out the ink. Then withing two milimeters of the end of the ink tube poke a hole straight through the tube. This will allow air to enter the barrel once it pushes up the airsoft bb. See pictures.

Step 10: Put it together

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Start by epoxying the schrader valve into one end of the pen tube. Then insert the piston (pen end cap with airsoft bb and spring attached). Then put the valve piece in (the tube with an eraser and the front a pen), epoxy this in place. Then insert the barrel with the hole inside of the pen tube.

Step 11: How it works/ Firing

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Its pretty simple, the spring pushes the bb down onto the eraser, this seals the barrel off which is inside the tube. As you fill the schrader valve with air, all the empty space inside of the pen acts a chamber like in a potato gun. Then you push the barrel inwards, it pushes the bb up and exposes the two holes in the barrel this provides a place for all the air pressure inside of the pen to release. You can shoot pretty much anything that fits down the barrel, I found that cutting the heads off nails works pretty good. I normally pump it up to about 100 psi, this is easy because of how small the chamber is. BE CAREFUL even though it is small it can get sharp objects up to high speed and could easily put your or anyone's eye out.
da_mann461 year ago
Could u make this in a video cuz i learn by watching a listining not reading pls it would help me a lot
theegghead1 year ago

this looks cool but I can't grasp how you fire the thing do you press down on the top of the barrel? Or do you pinch the barrel then push inwards?

ramicaza3 years ago
wow really cool how you actually made it out of a pen. I had an old one made from a marker but the 4mm barrel crumpled at 170psi :D... lol i made a new metal one though, and posted that here.
mafzal23 years ago
And now I am grounded for shooting my brother with this gun.
Rehtes4 years ago
dude nice blade
stop spamming, nobody cares.
improyo4 years ago
what do you glue the eraser to???? is in the ink cartige
sabladask4 years ago
see my instructable, i made a spring powerd piston bb gun.
good build
Dreistein4 years ago
a mini pellet gun
ilpug4 years ago
this is just a mini piston cannon. but very dangerous.
eel laup5 years ago
that is very clever can u make a pdf url so non pro members can download
make six, put them into a cap gun cylinder XD that would be soo cool
good ible accept i didn't see where you got the 1st barrel from, the one that goes on the outside of the ink cartridge.
Ben Nguyen5 years ago
OMB I think I'm gonna try this.
iTraceur6 years ago
Erm, I'm probably confused with the drawings, but when you push the trigger in, wouldn't it fire and hit your finger? I know I'm wrong, so could someone kindly explain, WHAT THE HELL?!
I think the idea is that you push the barrel inwards, by gripping it on both sides with two fingers. In other words, you don't have to put your finger over the end of the barrel to push it inwards. hopefully this helps LG
Nice name. Right. Guess that's why it's called a co-axial pengun then... It'd be 10 times better to have the button on the side though... TO THE WORKSHOP! Oh, hang on... TO THE PENCIL-CASE! QUACK!
thank you. the name refers to my inept gaming skills .......... btw, good luck making the pen gun, I would like to make one, but I don't nearly have enough skill to do so. LG
Meh, strike that side-button-pen-gun. Too hard to seal it off. Ok, new idea - you know those pens that rotate at the back, with a little mechanism in the middle that pushes the ink tube forward? Turns out they're really easy to seal off, and I've got a nice-looking one... BACK TO THE PENCIL-CASE! Oh, and relating to your pen-gun making skills (Or, rather, lack of), Who really cares? Is there anyone on this site who can say they studied for a degree in 'Pen-Gun Making'? QUACK! (iTraceur, PhD, D. Psych, PgMD)
which specific pencil did you get the "larger tubing" from? i wanna build this so bad....! awesome... faved
Jor2daje (author)  MadBricoleur6 years ago
Instead of building this design, I would try the gun jsr made that I linked in the intro. I made one based on that design and worked even better and is capable of much higher pressures.
Wambotrot6 years ago
I just don't get it.
i see what your saying. jrs is piloted from behind, while this is activated by a protruding out the front inner barrel. either way if you activated the shrader it would act just as jsr's. potato patato in my opinion, props for makeing it out of a pen. also, something like this could be modified into a rather more sinister auto injector. just saying, i dont really want to give that any more thought. cringe ick.
jamiespark6 years ago
really cool
JSR's pen gun is the same still though, cool
Surfguy216 years ago
Its called a co-axial pneumatic gun and the idea isnt his.jackssmirkingrevenge from spudfiles.com came up with the idea of making it small and like a pen.You should give credit to him and all the other people that came up with the co-axial idea.
http://www.spudfiles.com/forums/pneumatic-pen-gun-project-t7858.html
Jor2daje (author)  Surfguy216 years ago
Its different dude with a co-axial pneumatic you release a small amount of pilot air behind the piston that allows the piston to move backwards letting the air escape down the barrel. This gun has like a second barrel inside the other and you manually push the back. Also that gun was made out of copper and steel this is made entirely of pen parts. But I will agree that they did come up with a better idea before me.
O I see how it works now and sorry if I sounded mean before.Its a realy cool and concealable little gun.
Jor2daje (author)  Surfguy216 years ago
No problem, I definitely see the similarity between my gun and the one on spudfiles.
wow, very nice, but it could use a few things.... like a video of it working and more detailed instructions better quality pics but GREAT idea!
Evesneon6 years ago
this instructure is confussing... can u use the yellow box inside the pics ?
cheeseboy6 years ago
wow this is a new idea that I haven't seen before, I am definitely going to try this, good pictures too. Also it would be safer if you wrapped it in electrical tape so that if it exploded the shards wouldn't fly everywhere. 5.0!