In a survival situation several things are crucial, water, food, shelter, and security. In this instructable you will be taking care of two of these things by building your own survival crossbow. Once finished you will have a hand crafted tool that can be used to hunt for food, and keep you safe from hungry beasties (i.e. zombies). So get your zombie slayer face on, grab a few materials from the supplies list, and let's get started!
Step 1: Parts and Tools
- 2 - 1/2" x 6' Fence Picket Board
- Wood Glue
Trigger and Safety Pin
Bow and String
- 32" - 1 1/4" PVC (16" draw length)
- 2' 2x4 w/ 1" spacer blocks
- 22" - 3/4" pvc
- 5" - 1" pvc
Step 2: Stock
For the stock, I used a design from Jwilliamson. You may have seen his instructable, Building a Custom Rifle Stock. Complements to him for the design. He provided 3 printouts that you can use as a template, and I'm including them here.
Print out the stock design and cut it out. Then trace it to a piece of stock board and cut it out. A band saw would be ideal; however I used a hack saw and a wood rasp since I don't have a band saw. Test out the stock taking note of how it feels and make adjustments as necessary. I put a slight positive angle on the grip for comfort. Once satisfied, use this cutout as a template to cut out two more stocks. On the middle stock you will need to cut out a large section from behind the trigger to after the string release mechanism.
After everything is cut out, take some time to line the stocks up with each other to ensure general accuracy (you can fine tune it after it's glued together). If you're satisfied with the results then glue them together with wood glue and binding/clamping them together for 24 hours. Once they're ready you can make any detailed adjustments with a wood rasp, sand paper, or a dremel.
Step 3: Bow
To make the bow, I used a 1 1/4" PVC pipe and cut it to 32". Make three marks, one in the center (16"), and two marks an inch out from both sides of the center. To give your bow a subtle taper you can make a flattening jig with a two foot 2x4 and two pieces of 1" blocks on the corners of one end. Heat up the pipe with a heat gun until it's pliable, then use the jig to flatten it to size, one side at a time. Flatten one end by squeezing the pipe between a flat 2x4 and your jig, having the 1" blocks positioned between the center mark and the 15" mark. Clamp the boards down and allow the pipe to cool before releasing the clamps. Do this to both sides. This will create the proper shape (notice both ends are flat, and the center has depth with one flat side).
Put a recurve to your bow by first marking three inches from the ends. Heat the ends with a heat gun and use a small pot as your guide to shape the recurve. Curve it up to the three inch mark you made.
The string notches I made have a 3/4" gap between them. Mark the center of the bow's width and make two marks at 3/8" from the center mark. Now cut out the notches with a saw. Once you have the notches cut you can give the bow its proper curve. Tie a piece of paracord across the bow, then heat the center of the bow and pull up on the cord until the bow comes into shape. Keep it in place until it cools. Then you can cut your final cord and string your bow. I used two bowline knots to string it up. At this point I took the opportunity to paint the bow. It's not necessary, but I like the way olive drab looks over white.
To keep the bow in place I cut a 1/4" hole through the end of the stock and hammered a length of 1/4" dowel rod through the hole. I then used a long length of paracord to tie it down using the rod as an anchor. I used a clove hitch knot on the rod first and proceeded to wrap back and forth across the bow. Finally I finished with a clove hitch and tucked in the excess line.
Step 4: Make the Trigger System
Be sure to click through the pictures for added detailed notes about each process.
The elements of the trigger system include the trigger itself, and the string lock gear. I made the trigger from a spare piece of wood. I cut the general shape and used a wood rasp and sand paper to fashion the details. The trigger pivots on a bolt, and is spring loaded to bring it back into position after it's pulled.
The locking gear is made out of a piece of wood sandwiched between two washers. The washers are cut in the same shape. I used a dremel and a metal cutting wheel to cut the washers. Make sure you use proper safety precautions when cutting metal. Sparks will be flying so use gloves, ear protection and proper eye protection. DO NOT CUT METAL WITHOUT GOGGLES. After the washers and wood are cut to size, use super glue to bind them together. The gear is similar to the trigger in that it rotates on a bolt and returns by the aid of a spring.
More on Trigger Mechanics
The string is drawn and rests behind the top notch in the gear. The gear will want to rotate counter clock wise to release the string due to the force. Follow the counterclockwise force placed on the gear and you will run into the top of the trigger. The trigger then will have a clockwise force placed on it. For this reason I drove a nail just behind the top notch in the trigger to prevent the trigger from moving clockwise, and the gear from rotating counter clockwise (releasing the string). The string is locked into place since the gear will not move because the trigger will not move. When the trigger is pulled this pushes the gear clockwise slightly until the notch in the trigger releases the gear to act on the force placed on it by the string. The gear releases the string and the string pushes the dart forward. The gear and trigger are then pulled back into position by their springs. Hope this helps.
Step 5: Arrows
I made my own arrows using a 5/16" dowel rods cut to 18". I cut feathers down the center and super glued them to the back. I made a notch with a wood rasp where the arrow will rest on the string. Finally I made an arrow by cutting a washer to the proper shape and sharpened it. I attached the arrow by cutting a notch in the top of the dowel rod, sliding the arrow into place (it was snug), and wrapped twine around the end to keep the arrow in place.
To keep the arrow in place I cut two pieces of PVC and shaped them with the heat gun. After this I cut two ends off of tooth brushes and glued them to the pieces of PVC. I then screwed them onto the front sides of the crossbow stock. When the bow is cocked you can drop the arrow into place; the bristles will keep it there, you can even flip the crossbow upside down without losing the arrow!
Step 6: Test the Bow
You'll need some Crossbow Bolts for this step. Either make your own like I did, or buy them. Remember to be safe as you are now dealing with a dangerous tool. Make sure you aren't in a residential area when using your crossbow, this can seriously injure or kill someone. Once you have found a safe location set up your Target away from anything you don't want to shoot. Draw the string back until it is locked. Insert the bolt. Aim at the target and fire.