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How to Make a Crossbow. Build the Crossbow Step-by-Step. Making a crossbow from the longbow. Simple Pistol Crossbow Tutorial. Make a Crossbow from Scratch



An archer might consider it kin to a firearm. A shooter, on the other hand, most likely would think it a stock-mounted bow. To the general public, you wouldn't need a poll to know their feeling: It looks sinister enough to be a lethal weapon!

In short, there's not much doubt that the modern crossbow suffers an "identity crisis," but regardless of the mystery that still surrounds this curious hybrid, it's been gaining in popularity among hunters and targeteers alike. That trend hasn't gone unnoticed here at MOTHER EARTH NEWS.

With several avid bowhunters on the staff, and a research department eager to take on such an interesting challenge, it wasn't too difficult to get the ball rolling on a project that we figured might be a first in the field: designing and building a quality crossbow from scratch; testing its range, accuracy, and overall effectiveness; and then comparing its performance to that of traditional recurve and compound bows.



Crossbow Basics

The contemporary crossbow shares little beyond a basic design with its forebear, the medieval arbalest. Though both launch arrows (bolts) by means of a short bow transversely fixed to a stock, the superiority of modern materials — along with the improved geometry made possible by the use of such lightweight plastics, alloys, and composites — has turned what was a crude but effective weapon of war into an admirable piece of fairly uncomplicated technology.

Over the past few years, crossbow design has received considerable attention from various manufacturers, with the result that the old standard has been modified to run the gamut from a paramilitary-looking assault piece to an artistic expression of classical physics. And although these developments represent improvement in most cases, they're beyond the ability of all but the best-equipped crafts people to duplicate.

We chose the path of least resistance and used the simplest common denominators in our design. The stock of our crossbow consists of a center spine covered on each side by a strengthening flank. As a bolted-together unit, this flat-aluminum assembly serves as a combination barrel (or chase in crossbow terminology), trigger housing, handgrip, and shoulder extension.

The bow, or prod, is set into the nose of the forestock, and the two-piece trigger mechanism, cut from 1/4" plate steel, is pinned between the right and left flank pieces just below the receiver. Walnut stock inserts were trimmed and shaped to mate with the stock on either side of the shoulder extension.

Since the string does contact the barrel and is thus subject to friction, we added a pair of shoulder slides to the sides of the chase to reduce string wear and increase bolt velocity. Though these could also be made of walnut, we used Delrin (a Du Pont acetal resin) because it possesses an inherent lubricity.

Our crossbow's open sights consist simply of a front frame made of aluminum strap, and an alloy rear ring mounted to the receiver. Socket-head cap screws threaded into each of these brackets provide sighting beads, and the rear unit can be lowered or raised as necessary to zero the piece in at a specific range.

As far as we've been able to determine, a telescopic rifle sight is inappropriate on a crossbow for three reasons. First, the weapon's effective range is limited to 50 yards or so in all but an expert's hands, and at that distance, beads and the practiced naked eye should be sufficient. Second, a fired bolt's trajectory is such that, beyond 15 or more yards, its drop is enough to lower the point of impact many inches from the line of sight. Since most scopes are calibrated for rifles, the range of adjustment may be restrictive or the zeroing-in process tedious. Finally, a scope narrows the field of view and adds weight as well.

As our note at the beginning hinted, we made two different crossbows. The first, detailed in this article, is a functional, no-gadget rendition that's not overly complicated to assemble, which should serve as a fine fieldpiece or target piece. The second is a multiuse version that has some interesting features, but for the most part it's best suited to range shooting or backyard "plinking." It sports a folding front handgrip, a removable shoulder stock extension (which allows the long arm to convert to a hand piece), and no doubt the most practical feature of all, a positive trigger safety. (This last item, by the way, can be added to our standard crossbow if desired.)


Build the Crossbow Step-by-Step

You might be interested to know that we spent about $102 making our fieldpiece; that breaks down to approximately $14 worth of 1/4" aluminum flat stock (available at a scrapyard or a metals distributor); $8 in Delrin; $6 for the walnut billets; about $7 in assorted bolts, pins, and other minor hardware; and — here's the kicker — $67 worth of prod and Dacron bowstring.

Admittedly, it would have been nice if we'd been able to construct our own short bow by using common materials. Believe us, we tried! But the laminated fiberglass plods we laid up just didn't have adequate draw strength or the resiliency to stand up to repeated use, possibly because we weren't able to duplicate the heat-and-pressure curing process used by commercial manufacturers.

To ease construction, we've outlined the crossbow's major parts and drilling point, which will allow you to make scaled-up templates for the metal pieces. Be sure play it safe by matching the templates perfectly before taping them to the metal and scribing their outline, and be even more careful when actually cutting the aluminum stock: [1] the pieces must join closely or you'll be spending a lot of time with the file, and [2] the center spine's weak spot — the trigger guard — should not be any thinner than 7/32".

The best way to trim the parts accurately, by the way, is to use a band saw equipped with a metal-cutting blade. Because the smooth operation of the trigger and stringy catch depends in great measure upon the perfect alignment of the three stock components, we suggest that you postpone drilling the flank pieces until you've bored the 9/64" post holes according to the center points indicated on the template. Once those sockets are complete, clamp the aluminum center spine to one of the flanks and recheck the alignment, using the template cutout from the trigger housing. Then drill corresponding holes in the one flank piece

With that done, use No. 6 x 3/4" machine screws as temporary locating pins for the two bored components, and clamp the second flank piece in place. When you're satisfied that all three parts are evenly mated, drill the final member. Since the post screws are recessed, you'll need to countersink the exterior openings with larger bits according to the design of the screws and nuts you've chosen.

The steel trigger components have to be thinned by 1/64" in order to allow them freedom of movement within the stock. Once this is done, those parts can be drilled where indicated with a 1/8" bit, and the 1/8" x 3/4" expansion pin pivots can be pressed in and centered. The pivot pins ride in 9/64" sockets drilled into the right and left flank pieces; to be on the safe side, you might want to use the trigger-housing template cutout to position those openings accurately.

As we mentioned before, you can install a trigger safety mechanism according to our detail. Both the trigger and the safety catch are returned by small compression springs set into slots cut through the central spine.

Before assembling the stock for good, you'll want to bevel the inner surfaces of the barrel, and round the entire frame's outer edges. The rough work can be done with a grinder or file, and the metal then can be smoothed with emery cloth. Save the final extra-fine polishing for later, after you've bolted and pinned everything together and completed the cosmetic work.

The next portion of the project includes setting the bolt tang (the spring-steel leaf that holds the projectile snug against the barrel), adding the wooden (or Delrin) slides to the flanks, and cutting, shaping, and fastening the walnut inserts that dress the shoulder extension. (These pieces can be cut to shape using the template as a guide, then rounded with a sander and bolted or glued to the aluminum spine prior to being finished with varnish or tung oil.)

The front sight is a piece of 1/16" x 5/8" x 6 1/2" strap aluminum bent into an open frame configuration so the bolt can pass through it. It's fastened to the top of the forestock with two No. 6 x 1/4" machine screws, and a short cap screw locked through its crown serves as a bead. Though we used a machined ring at the rear (to provide a housing for an experimental scope sight), you can make an excellent sighting post by simply drilling and tapping a hole at the top of the receiver to accept a 632 socket-head cap screw about 1 1/2" in length. This can then be adjusted up or down for sighting.

We ordered a prod with a draw strength of 175 pounds, but even if you choose a lighter bow to lengthen string life you'll probably need a cocking lever to pull it into position. You can make one by bending four sections of 1/8" x 1" flat metal to create a two-armed, bolt-together yoke that uses mechanical advantage to ease cocking. A pair of slots in the stationary part of the lever hook into a 5/16" x 3" steel rod fitted into the crossbow's forestock (this should be located as indicated on the template and pressed in place before you install the prod), and another set of slots cut into the short "jack arms" catch the string. The fulcrum's just a movable collar that can be locked into the optimal position.

The prod is held in place by a 1/4" x 1" x 1 1/4" block of aluminum faced with a strip of hard rubber. A similar pad, glued to the rear of the prod socket, provides additional cushioning, and the metal block is forced tightly against the bow's face by a 1/4" x 1 3/4" cap screw threaded into a tapped hole at the nose of the stock.

Once the prod's installed, you'll have the pleasure of stringing it. Unless you're extraordinarily muscular, we'd suggest you purchase what's called a bastard string along with the regular Dacron cable. This set of strands is longer than the service string and thus can be slipped onto the prod more easily. It's then used to draw the bow's ears back to the cocked position so the real string can be looped in place. When that's done, both strings can be released with the trigger and the bastard removed. This is the only situation in which the crossbow should be "dry fired," since that practice can split the prod.The design is very simple and basic, so feel free to make any changes or variations. This tutorial is mostly focused on the crossbow body, and the trigger mechanism works extremely well. I am not going to include a tutorial for the prod because i am not good enough at making them to be teaching others :p. Here is the list of items i needed to make this crossbow, but you can change the size of the wood to your personal preference.

-Some bolts and nuts
-1/2 inch pressure board (or ply wood)
-8 mm pressure board (basically a thinner wood)
-Handsaw
-Drill
-Small screws
-Ruler
-Small springs (not required, but makes the trigger mechanism so much better)
-White glue
-Super glue
-Sandpaper (optional)
-File (highly recommended but optional)
-Pencil
Step 1: Gather Materials




You will need:

-A 2x4 in any type of wood, prefer few defects of course (at least 27" long)
-1/2" Sch 40 PVC pipe (at least 22" long)
-Red oak 1x2 (53" or more, other hardwoods are OK)
-A 1/2" x 5.5" x 48" poplar board
-3/8" poplar dowels (recommend three 48" dowels)
-5/16" dowel (at least 10")
-Larger dowel, 3/4" to 1" diameter (at least 6" long)
-Glue
-white glue
-epoxy
-hot glue stick
-String (I used 9/16" venetian blind chord, it is mixed polymers)
-Two 1/4-20 bolts, 3" long, with nuts.
-Wood screws (at least 6, ones that are 2"-3" long would be great)

OPTIONAL:
-Wood stain
-Spray on clear coat
-Brown spray paint
-1.5" wide hinge
-1.5" wide by 1/4" thick oak or poplar board (10")

All of that is available at a hardware store, mine was from Lowes mostly.

Step 2: Look at the Plans:




These pictures show all the dimensions and materials for the parts that need to be cut out and drilled. Mark these shapes onto your materials. Details about which material each part should be made from, hole sizes, etc, are written on the plans.

I don't think any more instruction is needed for this step unless the plans are unclear to you (they look fine to me but let me know if there is an issue).

Step 3: Cut the Parts



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Once you have all your cuts and drill places marked, cut everything out. A band saw and a power drill (prefer a drill press) would be very helpful for this. Also cut the 3/8" dowels into 8" pieces. Aside from the sanding this is most of the "work" of this project.

Step 4: The Arrow Box



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Get all the magazine parts (on the plans they are labeled magazine walls, magazine spacers, and arrow trough. For this step you will also need white glue, clamps (or weights), and idealy a dremmel tool or similar rotary sanding tool (but a round file, knife, or even coarse sand paper can work).

Sand the bottom edge of the front magazine spacer ("L" shaped one) so it is rounded concave. Then line up the magazine walls and spacers and glue them together (see pictures for position if it is not obvious to you). Clamp these together or stack weights on them while the glue dries. Once it is dry, sand it so all the layers line up smoothly without rough or uneven edges.

Then mark the lines shown in picture 6 on the arrow trough. There is one line going crossways on the board 12" back from the front (the end without the 1/4" hole is the front), and a line down the center from the front all the way back to the 12" line. Carve grooves along those lines with a dremmel sanding wheel. The front-to-back line is the trough the arrows ride in, and the side to side line is a notch that catches the bow string.

Glue the arrow trough on to the bottom of the magazine walls.

Cut or sand a 5/16 or 3/8" dowel in half lengthwise, so it is flat on one side. Cut about 10" of it and glue that 10" piece to the bottom of the arrow trough. Position it so it starts at the front edge of the arrow trough, is running lengthwise centered side to side.

Step 5: The Lever





This is very simple just glue and screw the lever handle on to the lever arms. White glue or epoxy are both good for this. I chose to round the other end of the lever arms for asthetics.

Step 6: The Stock



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Once you have cut it out as shown on the plan, all you need to do to this part is grind a 14" long groove into the top like on the arrow trough. The dowel on the bottom of the magazine will ride in this groove that you grind into the stock. Then screw and epoxy the 6" long piece of 7/8" dowel on to the back of the stock.

Step 7: The Bow







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Now you need the 22" long piece of 1/2" sch 40 pvc pipe with the markings on it as shown on the plans. We are going to heat it until it gets soft** then press it between two 2x4 boards. 5/8" thick wood spacers should be placed between the 2x4s alongside the pvc pipe to control the final thickness of the pressed pipe. Use clamps to push the 2x4s firmly together.

Once you have done that squirt some hot glue into both ends of the pipe, this will be a filler. Heat the 3" long sections on both ends of the pipe (one at a time) and press them as shown in picture 6. The end of the pipe should be completely closed after this pressing. Be sure that when you press it the pipe is rotated so that the part that was wider from being pressed between the 2x4s is the part that becomes flat.

Heat the center 1.5" wide section of the pipe and bend the bow limbs (each half of the pipe) slightly back and upward.

Then cut / sand the now flattened limb tips into a roughly parabolic shape and smooth out the edges with sand paper. File a notch into the limb tips for the string to catch on (called knocks). Drill holes and screw the bow into the notch in the stock.

For the string, just tie a loop in each end and make it so it looks just on the long side of the right length. Tie knots in the string to shorten it one at a time. Keep putting it on the bow to check if it's tight.

**To heat the pipe I am using a propane heater but you can use a torch, a heat gun, an electric or gas stovetop, camp fire, bbq, etc. Try to move the pipe around a lot in the heat to keep from scorching it. It will become soft and flexible.

Step 8: The Ammo



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Get your 8" long pieces of 3/8' dowel, they will be made into the bolts (arrows). Sand or file a + shaped notch into one end of each dowel. This will help the string catch it.

Then drill a hole in the other end of each one (drill press is much nicer for this than a hand drill). The exact size of the hole will depend on your arrow points. The arrow point is suppose to glue in to this hole. I used a 13/64" bit for mine. After you have the holes drilled epoxy in the arrow points. You may want to sand the area where dowel and point meet after gluing depending on how well the sizes match up.

Step 9: Finish



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Assemble the completed parts and test it:

Set the magazine on the stock, slip the lever over that and line up the holes, and put the bolts through (you don't need to put on the nuts right now). Then string the bow and push the lever forward until it catches in the notch in the arrow trough. Pull the lever back. You will immediately notice that it does NOT fire. Don't worry I haven't mislead you. Let the lever forward and push the string out of the notch with your thumbs. Now all you need to do to finish the mechanism is to sand the front edges of the notch (the one the string catches in) to smooth and round it off. Keep doing the test with the lever until you get it sanded smooth enough to where it does fire. Now it's done!

At this point I chose to stain and clearcoat the wood parts and paint the bow brown. Obviously you can decorate yours however you want. After you have done whatever surface treatments you are going to do, it is a good idea to put vegitable oil on the center of the bow string to help it slide easier and not wear through as fast.
Picture of How To Make An Extremely Powerful Wooden Crossbow!
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We were interested in each weapon's range, accuracy, and penetrating power, but ultimately we were searching for the crossbow's proper niche in the order of things.

Now we weren't interested in testing head-to-head with the Barnett offering, and we couldn't fairly pit a hand-held bow against a brace-mounted crossbow. So what we did was make a series of test firings with our standard model at distances of 10, 20, 30, 40, and 50 measured yards. Each group consisted of five shots with the same 24.94-gram overall (126.3-grain field point) Easton 14" aluminum bolt, and the resulting patterns then were measured and recorded. The crossbow was mounted and leveled in a sturdy brace, and a surveyor's transit was used to establish a direct line of sight to a given point on the target. The deviation of the points of impact from the sighting point was also noted. Wind conditions were fairly calm throughout the test.
 As you can see, the homemade crossbow held a respectable pattern, even out to 50 yards. (We suspect it would do the same beyond that point, but that's considered expert's range.) At that distance, drop was considerable (i.e., the weapon's barrel would have to be elevated in order to hit a target in a level line of sight) — but the same situation existed in the case of the more traditional hand-held bows.

Penetration was never a problem with any of the weapons we tested, since all the shafts buried themselves — some to the fletching — in the 12" of extruded polystyrene we used for a target backing. Considering the difference in draw weights between the traditional bows and the crossbows (and accounting for the standard arrows' additional mass), we could infer that prod strengths of more than 125 pounds amount to overkill; the extra power probably offers little, but taxes strings, bolts, and cocking convenience heavily. However, an understrength prod would be even less desirable unless it was matched with a short, light bolt. Our takedown pistol model uses a 75-pound prod and a 6" aluminum bolt, and has a power stroke of 6 1/4" compared to the larger weapon's 8 1/2". That’s fine for target shooting, but not really useful for hunting.

Regardless of draw weight, string life can be extended and bolt velocity increased slightly by applying a lubricative wax to the string and the barrel's shoulder slides.

In summary, much as we hate to burst a romantic balloon, we'll have to concede to the facts: Although a crossbow has the advantages of compactness and mechanical cocking and locking (it can be held at full draw without strain on the user), it is really no more accurate than a conventional bow in proficient hands, can't be loaded and fired as quickly, and doesn't even approach the overall effectiveness of a rifle. Nonetheless, it's a valid sporting tool that's slowly but surely coming into its own once again.
Field Test Results

MODEL TESTED: Homemade, aluminum frame; walnut inserts; Delrin shoulder slides
PROD: Barnett Commando, heat /pressure-cured fiberglass, 175-pound draw
WEIGHT: 6 pounds, 5 1/2 ounces
OVERALL LENGTH: 31"
OVERALL WIDTH: 26 "
POWER STROKE: 8 1/2"
SIGHTS: Open, adjustable rear post
BOLT: Easton, 14" aluminum 24.94 grams overall including 126.3-grain fieldpoint