Introduction: How to Make a Compressed Air Gun
In this build i will be making a compressed air gun. This can be used as a toy guy or dart gun and uses compressed air to fire a projectile. It is made out of mostly household materials and can be refilled with air pressure by a bike pump. For this build i start off by using a refillable compressed air can that i made in a previous build so i will start off by summarizing how i built that in the first part, but for a more detailed explanation on making the compressed air tank i recommend you look at the video.
Materials for the Compressed air can portion:
-any empty aerosol can
-a bike inner tube
-a wooden dowel
-some small pieces of wood
-epoxy or super glue
Materials for the Gun:
-the compressed air can
-a clothes hanger
Step 1: Building the Refillable Air Tank (Summary)
Before we get into building the gun we have to first touch on the refillable compressed air can (which is what is mainly used for this build). I have a short video (and will eventually have an instructable) dedicated to showing how to build the can , so i will only be providing a summary here.
To build the air tank i start of by obtaining an empty aerosol can. I also obtain a bike inner tube and cut out the valve part of the inner tube. This will provide us with a way to easily refill the can. I then drill a hole in the bottom of the can and poke a clothes hanger into it to break the rubber divider which dives the top and bottom of the can. Once that is done i can insert the valve into the hole i drilled and seal around it with epoxy.
After that i take off the top of the can exposing a valve which when you push on it, it lets air out of the tank. With the top valve exposed all that is left is to attach a tube to it and create a contraption so that the valve can be easily pushed in. To do this all i need is a dowel and a couple scrap pieces of wood. Once the top end is complete the refillable air tank be emptied using the mechanism at the top and refilled at the bottom by attaching a bike pump
Step 2: Attaching the Barrel
Once the compressed air tank is made we can now focus on building the gun. To start off i make the barrel of the gun using a straw for it. A straw worked for the size of my homemade projectile, but if you decide to use a different projectile make sure it fits in the barrel perfectly. To attach the straw i simply cut a short piece of tube and add it to the thin tube leaving the gun. After that i slide the straw into the larger tube. Since it wasn't airtight i wrapped tape around the straw to increase it diameter so it would fit tight.
Step 3: Aesthetic for the Barrel
To make the barrel look more aesthetically pleasing and to give it some strength i used rolls of paper. I started rolling one thin roll around the straw. After that i also rolled a thicker roll of paper around the thin roll. This gave me a thick and thin roll of paper which was then cut to size and glued into position around the barrel.
Step 4: Building the Handle
To build the handle of the gun i used a few more of the wider rolls of paper from the previous step and i glued them into place (as you can see in the pictures) to make the handle. The construction of the handle is based on preference, but i found the design i used looked decent and felt good to hold.
After completing the handle i also added small tubes of paper above and below the barrel for both aesthetics and support.
Step 5: Holder for the Projectiles
To complete the handle and barrel i wrapped paper around the base of the barrel and the entire handle. This was strictly for looks and is not mandatory at all.
After this i used straws as something to hold the projectile. I used straws because the projectiles are going to be made to fit perfectly inside the barrel which is a straw, this means they will also fit nicely in the holders.
To make and attach the holders i cut a straw into 4 peices and glued it to the base of the barrel
Step 6: Making the Projectiles
For the projectiles to work there is only have one main constraint; they must fit tightly in the barrel and not allow much air to pass. To create my projectiles i cut a strip of paper and rolled it into a cylinder slightly smaller then the straw. To hold it together and to reduce friction i wrapped the projectile in some tape until it fit perfectly in the barrel. After that i cut pieces of clothes hanger and put them into the center of the projectile and glued it in there so no air could pass
Step 7: Testing
Once you have made a few projectiles you can load them up into the holder and push one projectile into the barrel. To make the projectile shoot as powerful as possible make sure to push it all the way back into the barrel. To test the gun it first must contain air pressure. To do this i attach it to a bike pump and usually fill it to a maximum of 70 psi. Once filled with air and loaded, the gun can now be shot at a target. From experience it seems to shoot very fast and it is able to shoot 20 or so rounds before you would have to add more pressurized air.
If you wish to see the tests and how it worked you should check out my full video
This concludes the project, if you make this be sure to be safe and let me know how the build goes.