Making a Folding Crossbow

I have always wanted to make a crossbow but never had the time to do it. Finally last week I took a few days off work so I made one.Here I am going to demonstrate the process of making it.

Here is a video showing how I made it step by step:

And the plans:

Step 1: Making the Jig

Tools and materials for this step:

• A piece of 20 mm thick plywood at least 60 cm long
• 4 blocks of wood (mine were 4 x 4 x 6 cm)
• 4 screws 8 cm long
• Screwdriver or drill

Before we start making anything else, we should make a jig. We are going to need this jig to pre-bend the wood for the limbs and also as a support for gluing the limbs.

It's construction is very simple, just a piece of plywood or melamine, and four wooden blocks screwed on it. The exact plan and dimensions provided in the embedded pdf file (L1). So if you haven't done that already, go and download it.

At the end you should have something like this

Step 2: Bending the Wood

Tools and materials for this step:

• 4 strips of wood (55 x 7 x 0.4 cm) I have used beech
• Our jig
• A few clamps
• Bucket with hot water
• Heat gun (optional)

Its a good idea to pre bend the wooden strips for the limbs before gluing them. Makes lamination easier and you wont have to worry about the wood cracking.

The process is simple, first place the wooden strips in a bucket filled with hot water for about ten minutes. This will soften the woods fibers and make it more pliable. After ten minutes remove them from the water and place them on the jig as shown on the picture 8. I have also used a heat gun while placing them on the jig just to prevent the wood from getting cold. But that is not really necessary.

Finally clamp the strips together to prevent the wood from warping.

*TIP:We have only one jig and we want to make two limbs. Make one limb, let it sit overnight and then make the other one, don't forget that making the limbs is the most crucial step in the whole project. If you don't rush and take your time you will make a very nice and strong crossbow

Step 3: Gluing the Limbs

Tools and materials for this step:

• Our bent strips of wood
• A non bent strip of wood cut in half
• Our jig
• Wood glue
• A few clamps

The process is the same as the previous step, the only difference is that we add glue between the two strips of wood. We also and a third strip of wood about 15 cm from the other strips edge just to reinforce each limb as shown on the picture 5.

Finally add as many clamps as you can to hold the two strips together. We don't want gaps between them!

At the end of this step you should have something like this.

Glue one limb at the time, let the glue cure overnight and then glue the other one. If you can leave the limb on the jig for more than 48 hours that would be great, and thats because we want the glue fully cured before we continue to the next step.

Step 4: Attaching the Risers

Tools and materials for this step:

• 13 x 4.5 x 4.3 cm block of wood
• Saw or jig saw or band saw
• Sandpaper
• Drill
• 10mm drill bit
• 8cm Carriage bolts, washers and nuts
• Wrench
• Hacksaw or angle grinder
• 2 Hinges

On this step we are going to make the risers on which we will attach the limbs. These are just triangular pieces of wood 4.5 x 12.5 cm. (R1 on the plans)

Once we have them cut we need to attach the limbs, simply by making four holes on each limb and riser and secure them using four bolts.

Finally we want to cut the bolts with an angle grinder or hacksaw,make a notch in which we will attach the hinge for the limb.

Drill some pilot holes for the hinge screws and attach the hinge on the limb.

Step 5: Trigger Mechanism

Tools and materials for this step:

• 20mm thick plywood
• Copping saw or scroll saw or band saw
• Sanding paper or vertical sander
• Drill
• 6 mm drill bit

On a piece of 20mm thick plywood attach the trigger plans (T1) using some double sided tape and cut the parts on the band saw or with a copping saw or scroll saw. Next drill a pivot hole on each part according to the plans provided. If you want you can shape the trigger using an orbital sander like this to make it a bit more comfortable to touch. That is optional though! After a bit of sanding you should have something like this.

Step 6: Making the Grip and Foregrip

Tools and materials for this step:

• Piece of wood 30 x 15 x 3.6 cm
• Double sided tape
• Sanding paper or vertical sander
• Chisel (12 mm is ok)
• Drill
• 6 mm drill bit
• Saw or copping saw or jig saw or band saw
• Wood glue
• 3.5 x 3.5 wood screws
• Screwdriver

On a piece of wood attach the grip and foregrip plans (G1 and G2) with some double sided tape and cut the shape on the band saw or a jig saw. Sand it and make the hole for the trigger using a chisel.

Attach the two pieces together with some wood glue and screws.

At the end of this step you should have something like this

Step 7: Attaching the Trigger Mechanism (and Cover Plates)

Tools and materials for this step:

• 3 3mm thick nails
• scroll saw or band saw
• Drill
• 4mm drill bit
• Countersink
• 4 25mm screws

Mark the screw positions on the grip according to the plans (P1) and drill three holes all the way through the wood. Attach the trigger mechanism inside the grip using three 3mm thick nails.

Finally cut out the cover plates and attach them on both sides of the grip. (While making the crossbow I have used a different design for the cover plates, just because I didnt have the plans with me so I came up with a different shape.)

At the end of this step you should have something like this

Step 8: Attaching the Limbs

Tools and materials for this step:

• Drill
• 2mm Drill bit
• 4 35 mm wood screws
• 4 30 mm wood screws

Attach the limbs as shown on the pictures above. Predrill the holes for the screws to prevent wood from cracking. Finally attach two L brackets on the limbs using 4 30 mm wood screws.

Step 9: Attaching the String

Tools and materials for this step:

• 2 mm thick paracord
• Threaded rod
• 2 Wing nuts

We want to make sure that the string is stretched when we unfold the crossbow but not very tight. it should be easy for us to unfold the crossbow.

Step 10: Making the Arrow Track

Tools and materials for this step:

• 2 strips of wood 16 x 0.6 x 0.3 cm
• 2 strips of wood 9.5 x 0.6 x 0.3 cm
• Wood glue
• Small nails or nail gun

Glue the strips as shown on the pictures above and secure them with some small nails or brad nails. Those are important as they keep the arrow straight.

Step 11: Its All Done!

Hope you enjoyed my instructable.

P.S: Have in mind that this crossbow might be dangerous for you or for other people. Please be careful when using it and throughout the building process. Never use it again other people, pets or yourself. I am not responsible for any injuries.

Please be careful and have fun.

Thank you.