Straight grain for straight shooting
Designed and written by Beth Ireland
Built by Ken Burton
The crossbow was the weapon of choice for hundreds of years before gunpowder made it obsolete in the eyes of the military. But the archaic armament lives on today as a great piece of sporting gear. And it’s a lot of fun to make one of your own. The kind of bow used on a crossbow is called a flat bow and is different from a traditional bow that has a shaped cross-section. The style of the bow shown here is a mix of elements from crossbows of the dark, and middle ages.
Making a crossbow is a welcome diversion from the rigors of furniture making in that it doesn’t require precise joint fitting—much of the build is done by eye and by feel. What’s more, it’s an opportunity to strengthen your hand tool skill as you shape the stock and bow. And you’ll get practice reading and understanding grain. Choosing the right piece of wood for the bow is key to the success of the project. I suggest starting with a nice straight piece of ash, as it is naturally springy and displays prominent grain that is relatively easy to read. What follows is my plan for getting you armed and ready.
Order of Work
- Mill bow stock
- Shape bow and add string
- Fit bow to stock
- Make trigger mechanism
- Shape stock and make bolts
- Perforate your target
Three wood parts, a brass rod, and paracord
This crossbow consists of three wooden parts along with a short section of brass rod to serve as the trigger pivot and a length of paracord for the bowstring. The most important piece is the bow itself: A length of straight-grained 8/4 ash cut so the growth rings run parallel to the outer face of the bow is best. The wood for the body or stock can be anything of the appropriate size that shapes well. This one is poplar. Finally, the trigger should be cut from a strong piece of hardwood that holds up under heavy use, maybe one of those exotic scraps you’ve been saving.
Find the bow in your stock
The wood for the bow blank should be flatsawn, with the growth rings running parallel to the bow’s front face. This helps to keep the bow from splitting as it flexes. Riven wood split from a log would be best, but if you’re using a lumberyard board, use straight-grained 8/4 stock, and cut it to suit. There is a bow waiting inside most blanks of ash, but to find it, you will have to follow the grain and most likely waste some wood.
Lay out your bow blank along the straightest portion of grain on your workpiece. Rip away the bulk of the board at the table saw, and cut off the rest at the bandsaw with its table angled to match your layout. Then, at your bench, shape the blank to follow one growth ring.
A New Kind of Scraper
You don’t have to do much woodworking before you recognize the value of a card scraper. But those simple tools can be hard on your hands. I’ve found that I can make my own scrapers from used blades from reciprocating saws. And adding handles to them really takes a lot of the pressure off my fingers and hands. Sharpen with a burnisher as you would a regular card scraper.
Shape the bow
With the grain in the bow blank properly oriented (the side you just dressed should become the front of the bow), it’s time to cut the bow to its final shape. The ends are tapered in width and thickness. Mark the bow’s center, and draw two lines across the bow to indicate the thickness of the stock equidistant from the centerline. Lay out the width tapers on the back of the bow and make these cuts on the band saw. Hand plane to smooth away the saw marks. Then taper the bow in thickness, checking progress as you go. Once the sides are tapered, notch each end for the bowstring.
Thick to thin. Hand plane the back of the bow to taper its thickness from the center towards the ends. Note: as you plane, you’ll be cutting through several growth layers, but this isn’t a problem on the back side of the bow.
Flexibility test. Stop periodically to check your progress by bending the bow over a scrap. Look for a smooth, symmetrical curve.
Three-sided notch. File notches for the bowstring about 5⁄8" in from the ends. Cut them in the edges and across the bow’s front face.
Add the Bowstring
With the bow shaped and notched, it’s time to add the bowstring. Use a length of paracord (see Buyer’s Guide, below) tied at each end in a figure 8 loop (see Knot Detail in the illustration above). It will take some trial and error to get the loops placed so they give the bow a slight flex at rest so cut a length of cord about 10" longer than your bow to begin. Then make a “tiller board” to see how the bow draws. This is simply a 1×3 with a series of 2" sawtooth-shaped notches cut its edge starting 4" from one end. Cut a 10° angle in that end to mimic the angle of the bow in the stock. Look for symmetry as you flex the bow on the tiller board. Remove the string and shave away more material as needed.
At ease. Position the loops on the bow string to give the bow about a 2" flex at rest.
Fit the bow to the stock
Mill the stock blank to the size shown on page 41. Then cut the bolt (crossbow arrow) groove along the stock’s top edge on the table saw. Switch to a dado blade and cut the slot for the bow. Insert the bow in the stock, and mark the location of the anchor line (where the bowstring reaches at full draw). The drawing on page 41 is based on the bow shown here, so adapt the dimensions as needed to match how your bow behaves.
Cut the notch. Set up a dado blade to match the bow thickness and tilt it to 10°. Adjust the blade height so the back edge of the bow will sit flush with the top of the stock. Make the cut 11⁄2" in from the end.
Find the anchor line. The position of the anchor line is based on the draw length of your bow. With the bow friction-fit in the stock, secure the stock in a vise, pull the string back to its maximum draw, and make a mark.
Make the trigger and shape the stock
The firing mechanism consists of a wooden trigger that rests in a recess in the stock and pivots on a brass rod. Depressing the rear of the trigger pivots its front upward, lifting the cord over the anchor, and launching the bolt. This happens much faster than you can read it. The location of the trigger recess is based on the location of your anchor line. Rout the recess in the stock, then shape the stock and the trigger (see p. 41) on the band saw. Finally, drill the holes for the brass rod.
Drill the pivot. Drill a 3⁄16"-diameter hole through the trigger, where shown in the drawing. Use that hole to locate the stock’s pivot hole. Aim for the front tip of the trigger to be even with the anchor line at the top of the groove.
Test shot and finishing touches
Friction-fit the bow in the stock and install the trigger. Now, it’s time to test your creation. Cut a 3/8" diameter dowel about 1" longer than your draw, and sharpen one end in a pencil sharpener. Wrap the other end with some duct tape to make fins—traditional crossbow bolts only had two.
Pull back the bowstring and hook it over the anchor. Load your bolt in the V-groove, and take steady aim at something (not someone) well out of harm’s way. Fire away. If the bolt flies up instead of straight ahead, you may need a deeper V-groove or to use a larger diameter dowel. Once your crossbow fires true, sand, shape, and finish the stock to your liking. I did a little chip carving and painted it with milk paint, using Danish oil to finish the bow and trigger before shimming the bow in place.
Embellish. Round the stock’s edges with a block plane, spokeshave, and/or rasps and files. Be sure to round the edges of the anchor notch to prevent wear on your bowstring. Sand, then finish and carve as you see fit.
