Introduction: DIY Bolt Action Air Rifle
After having successfully completed an air powered bazooka I decided it was time for me to try my hand at making a rifle. Now I didn't want to build just any old rifle, no, it had to be air powered. Yes I know there are compressed air rifles already on the market but this one would truly be my own. So without further ado lets get started.e
Step 1: Parts List
Or a similar solenoid valve that has 1/2 inch threads.
1x 3/4 inch metal end cap
1x 1/2 inch metal male to male adapter
1x 3/4 inch to 1/2 inch metal reducer
1x 1/2 inch PVC Female to push fit adapter
1x length of 1/2 inch PVC piping. The length is entirely up to you. This is the piece that will serve as your barrel. I got a piece of 2 foot 1/2 inch PVC precut at Home Depot for $1.50
1x length of 3/4 inch metal piping. Mine is approximately 18 inches long.
1x 1/8 inch schrader bike valve
1x Piece of aluminium approximately 50mm wide by 75mm long and 3mm thick.
2x M5 bolts mine was 50mm long and I cut it down to the correct size for this project
1x Power source for the 12 volt solenoid. I'm using 3 Li-Ion batteries. If you take this route you will need to either 3d print a holder for the batteries or purchase them. Here are some links:
1x Push button (Mine is 36mm tall, 10mm wide and 16mm deep) I salvaged this from an old electronics board. I will include the trigger handle Solid-works part file so you can modify it to fit your existing switch.
5/32 inch drill bit
Soldering iron and solder
A Dremel or a hack saw
Small files for cleaning up 3D printed parts and to make everything fit.
A 3D printer is recommended either using your own, a friends, or one of the many online services.
The 3D printed parts needed are the butt stock, air reservoir chamber supports, stock front end and trigger assembly. These parts can be customized and made out of wood for those without access to a 3D printer.
Step 2: Assembling the Air Chamber
This process involves drilling an 11/32 inch hole into the end cap. Go slowly so you don't dull your drill bit. A drill press is recommended but not necessary a regular power drill will work just fine.
Then you must tap the hole to fit the 1/8 inch schrader bike valve. Go slowly again and if the tap gets stuck on a chip back the tap up a bit to break it loose. When you are done tapping the hole use some ptfe paste or tape on the the schrader valve and screw it in place.
Now take you piece of 3/4 inch metal piece and use tape or paste on both ends. Screw the 3/4 inch to 1/2 inch adapter on one end and the end cap on the other. Then using the same technique as before to screw the 1/2 inch male to male adapter into the reducer.
Your air chamber is now complete.
Step 3: Stock
The butt stock was entirely 3D printed I will upload the stl files so you can 3D print it as well. I have also included the Solid-works part so that you can modify it if you feel it is necessary. If you do not have a 3D printer you can modify the butt to your liking using wood or any other type of material it just has to be able to withstand a small amount of kick.
Note that the channel for the angle iron is set at a 100 degree angle due to the fact that my piece of angle iron was not perfectly squared up.
2 supports were 3D printed to hold the air chamber in place on the stock. They hold the air chamber at the correct angle to allow it to sit upright when connected to the stock.
The stock front end has a cut in it to allow the 1/2 inch Male to Male fitting to pass through.
Push the two pieces of angle iron into the slots on the butt stock. Use glue to secure the part in place. Put zip ties through the holes in the sides of the supports and attach the supports to the air reservoir.
Step 4: Trigger Housing
Now take your piece of aluminium and drill a hole 25mm from the side and 10mm from the top. Use a 5/32 drill bit or equivalent and drill all the way through. Use the M5x0.8 tap to tap the hole you just drilled. Now 30mm from the top cut inwards 15mm on both sides so the you are left with a shaft 20mm wide. Insert your now T shaped piece of aluminium into the slot at the top and glue it in place. Then take you switch and glue it into place as well.
Now take the stock front end and insert the M5 bolt through the hole and bolt the trigger and stock front end together like it is show in the pictures. When that is bolted together cut the bolt so that it is flush with the end of the aluminium plate. Slot the stock front end onto the angle iron and glue it in place. Then using zip ties or glue, zip ties would be better if you ever want to mod the gun, secure the air chamber in place on the angle iron as shown in the picture and then you are done with this step. Now onto the barrel.
Step 5: The Barrel
Cut your 1/2 inch PVC to your desired barrel length. Then use the purple PVC primer on the inside of the push fit adapter and on the outside of the 1/2 inch PVC pipe. Then, using PVC cement, glue the barrel to the female to push fit adapter.
Now take the PDF file I've included and print it at 100% scale or full scale just so long as its the same size as it is displayed on the PDF. Cut out the black shape and lay it on the PVC and tape it down. This is going to be the hole cut for the bolt action so make sure to put it in a place that is comfortable for you to reach and action. Then using a drill drill holes all around the template. Make sure the holes are close together so that you can easily remove the piece you are trying to cut out. If you didn't get the holes close enough to remove simply you a Dremel or side cutters to remove the extra material between the holes. Then use a small file and smooth out the edges.
Now 3D print the bolt or make it out of wood dowel rod. I have included the STL and Solid-Works parts so that you can get the dimensions. Now for the tricky part; You have to press the bolt down the barrel while making sure the screw hole lines up with the cut out on the PVC. Use a little petroleum jelly to lube it up and create a bit of an air seal. When you are done screw an M5 bolt into the hole and you are done.
If you are confident in your Dremel abilities then use it to make the cuts and smooth out the cuts with a file.
If you do not want the air rifle to be bolt action you can skip this step and screw the barrel into the other end of the solenoid and you're done. Simply push whatever you want to shoot out down the barrel.
Now screw the PVC into the other end of the solenoid and you are done. HUZZAH!!!
Step 6: Wiring It All Up
Wire up all of the batteries in series so that you have a nominal voltage of 11.1 volts which is enough to trigger the solenoid. Then using the wiring diagram I provided wire everything and cable manage as best as possible.
Step 7: Customizations
I decided to pick up some extra materials to customize my air rifle a bit.
1x 33mm by 33mm by 4 foot piece of wood. This was sold as a piece of decking material and I got it for about $2 US dollars. This will be used later as a hand grip to hold the barrel.
1x 3/4 inch to 1/2 inch PVC push fit to screw adapter so that I can have a bigger barrel should I want to shoot larger objects.
1x 1/2 inch PVC T fitting so that I can make a fore grip built right into the barrel
Step 8: Did You Like This Project?
If you did perhaps you'll like some of my upcoming projects on my Youtube channel. I am in the process of building an electric mountain board and a CNC mill both for cheap.
Check me out at: https://www.youtube.com/channel/UCCujhPHD-B-X-XYw-...
And perhaps consider supporting me on Patreon.