Homemade Crossbow

This is one of my crossbows that I made using my own design and method. I created several crossbows by trail and error and this is my most successful one. You may have to search around for parts because the parts I used were random scrap.                    

But you will need these:                                                                                                                                                                                                 Fiberglass strips(from a construction site or from an unwanted bow)                                                                                                                 Piece of wood 2'X6''X4''                                                                                                                                                                                                  An air-soft gun(preferably one you don't like)                                                                                                                                                             fishing line(20 pound or higher)                                                                                                                                                                                       
2 nails
nylon string
thick wire coat hanger
flat strip of steel with a small hole in the middle
thick cylindrical piece of wood 
2 foot wooden dowels 3/16 inches in diameter
plastic coat hangers

I started out this crossbow by using the fishing line to tie two strips of fiberglass together from an old cheap bow. I made some crossbows using poplar and palm fronds instead of fiberglass, but this one was my best. I put gloves on so my hands won't get cut while I tightly wrap the line around the two strips and let the two strips overlap about 6 inches. I then used a hand saw to cut two grooves on the wood piece that is the base of the crossbow around 4 inches down from where the fiberglass will be attached. You can see how deep to make the grooves in the image. Put gloves on again and very tightly tie the connected fiberglass strips to the crossbow base piece. Make sure it is tied on tight enough that the fiberglass is firmly attached and won't shift. Also make sure that the line tied on will not obstruct the passage that the bolt will be fired from.

This step is optional but it greatly makes reloading the crossbow faster and more comfortable. Obtain a slightly curved piece of wood about a foot long and screw it to the backside of the crossbow. This is the belly brace which is the yellow thing. When reloading the crossbow you can rest the belly brace on your belly or on your waist.

Next is to bend back the fiberglass and tie the nylon drawstring on. I pushed the crossbow against the edge of a wall and the ground and used my knee to keep it bent while I tied on the string, but you can have somebody else to tie it on for you if you want. Make sure there is sufficient tension keeping the drawstring taught.

Do the power test. Pull back on the drawstring as far as you want it to go. Do not try to attempt to pull it back as far as you possibly can. Decide on a good position where the drawstring is pulled back to that is not too powerful nor too weak, yet you may want it to be pretty powerful. This desired position is where the firing mechanism will be placed, mark it with a pencil or marker.

Screw on the hand grip on the crossbow a little towards the fiberglass end from the middle of the crossbow. Make sure the screws sink into the wood a little so they won't obstruct the bolt's firing path.

This part will take the most time and effort. Get your air-soft gun and remove the top portion of it. There are many different models of air-soft guns but in the one pictured there is a metal peg I pushed out with a screwdriver. Once the top is off, take out and examine the trigger. The trigger is a solid metal piece that has two holes through it. The bigger hole is for the rotational axis of the trigger and the smaller hole is where the coat hanger wire comes in. Use wire cutters to shape out a strip of wire that will fit through the small hole. use pliers to shape the wire like how it is in the picture and insert it into the small hole. Put the trigger back into the gun. You may need to truncate the air-soft gun and trim back on plastic that hinders the free rotation of the wire.

Cut out a rectangular shaped hole on the crossbow base and keep in mind to position the wire where the mark placed is. Push the gun into that hole and screw it in. I had to drill a hole and use nuts and bolts. Note that pulling the trigger moves the wire forward. Let the trigger fully retract and take the flat piece of metal and feed the wire trough the hole. The piece of metal has to be behind the trigger in order for the crossbow to work. Screw that piece of metal to the crossbow base. Use wire cutters to trim the wire sticking out of the hole so that only a few centimeters stick out.

Pound in two nails to the crossbow as seen in the picture. These nails will stabilize the bolt while it is being loaded.
Get the wooden dowels to make the bolts.Laterally cut 3 inches off of one end of the dowel so that a semicircle prism sticks out. Cut 3 inches out of a plastic coat hanger and sand half of that piece down so that it is a semicircular prism. Tie the plastic to the cut area on the dowel very tightly with the fishing line. Leave an area exposed for a hole and don't tie too close to the end of the bolt. Cut a notch at the end of the bolt for the drawstring to lie on. Then drill a small hole about the diameter of the wire into the plastic part of the bolt. You can put an awl in a flame and melt a hole into the plastic.I used tape  for the fletchings for the bolts. Put them on so that the bolt will lie flat on the crossbow. You can decide to put a screw on the end of the bolt or attach something sharp.

You now have a completed crossbow with some ammo.
To load the crossbow pull the drawstring over the bolt and snugly push the exposed wire into the hole in the bolt.Pull the drawstring back and release it on the notch in the bolt. Aim and Fire. The wire will fall down when the trigger is pulled and you can simply tip the crossbow upside down to get the wire back into the hole.

This crossbow is very powerful. I shot a steel can and pierced into it by a few inches. Be careful with your homemade crossbows.