From The Crossbow, Construction of a Powerful Crossbow  by Sir Ralph Payne-Gallwey

The Stock

A. The opening to take the steel bow. The depth of this opening exactly fits the width of the bow at its center, and is 2 in. long and 1 5/8 in. deep. The opening is sloped upward so as to give the bow a slight cant up, which, together with the upward curve of the ends of the bow, enables the crossbow string to slide, without friction, along the bolt groove on the top of the crossbow stock.

B. The oblong hole is 1 3/4 in. long and 1/2 in. wide and holds the metal wedges (Figs. 62, 63) that secure the bow tight to the stock. The distance between this hole and the opening for the bow at A, is 3 in.

C. The hollow, cut transversely through the stock, for the revolving nut and its socket (Fig. 53).

The dimensions of the crossbow stock are:

Overall Length, D to F, 3 ft.
Depth Front, D to H, 3 1/4 in.
Depth Back F, 1 3/4 in.
Thickness, 1 1/2 in. from D to E, tapering to 1 1/4 in. at the Back F.
From the Front,  D, to the center of the opening at C (axle of the revolving nut, 14 in.

The stock of a crossbow is cut from close and straight grain hardwood, such as beech with the grain, running lengthwise for strength.

The sight is screwed to the top of the end of the crossbow stock

The sighting arrangement of a Medieval crossbow is quick and effective . It consists of a strip of wood the same thickness as the stock, and is 1 ft. in length and 3/4 in. high (Fig. 47). The top of the strip is rounded, and has two or three large sloped transverse notches of varied depths (Fig. 47).

The crossbowman grasped the trigger and the handled of the stock of his crossbow with  his right hand and took aim, over the sharp point formed by the joint of the bent thumb, as it rested across one of the notches in the wooden strip. The first joint of the thumb and the uppermost edge of the head of the bolt, laying in the groove of the stock, gave the alignment. When the soldier was on the march with his crossbow over his shoulder, these notches allowed  a firm grip for the fingers of one hand.

The head of the bolt, whether blunt or pointed, was  usually four-sided, with four longitudinal edges. One of these edges was always arranged to be upright to act as a foresight when the butt of the bolt was placed between the fingers of the nut and against the bowstring.

Being of different depths, the notches in the strip of wood along the thumb of the right hand, acting as a backlight, could be placed higher or lower, according to the trajectory required.

The aft end of the sighting strip (Fig. 47) is cut away for a length of 3 in. and a depth of 1/4 in. This allows the sheath of the windlass to be fitted over the end of the crossbow stock (Fig. 73, upper plan).

The end of crossbow stock is covered with a cap of thin metal for a length of 2 in. to protect it from the friction of the windlass sheath, A (Fig. 4)..

For crossbows with long stocks, such as those bent with a windlass and its ropes, the small or pointed end of the stock (known as the tiller) was either squeezed tight inside the right armpit, or was rested for a few inches on the top of the right shoulder. The left hand grasped the enlarged part of the under surface of the stock, and the left elbow rested on the left hip or against the left side, in order to support the crossbow in a horizontal position. The fingers of the right hand were free to work the trigger, and the right thumb to act as a backlight The face was inclined over the stock, bringing the right eye in line with the groove and bolt (Fig. 36).

Louis XI. of France, 1461-1483, issued a military order that crossbowmen in his army should have the visors of their helmets cut away on the right side opposite the cheek, so that the visor would not interfere with the stock of the crossbow when the crossbowman was taking aim.

The Revolving Nut and Its Socket

The notch A, in the nut, is exactly below - i.e. opposite to - the curved fingers which hold the bow-string.

The notch is 1/2 in. wide, and 1/8 in. deep on its squared face where it engages the point of the trigger inside the stock.

The longitudinal opening B is 1/2 in. wide and is cut through the under side of the socket to allow the point of the trigger to reach and engage the notch in the nut, as shown in Fig. 55.

The nut and its socket should be of steel and the nut must revolve accurately and closely in its socket. The nut is 1 1/2 in. in diameter and 1 1/4 in. thick. The socket, in which it revolves, is 1/4  in. more than a half circle, so as to bring the center hole of the nut 1/4  in. below the surface of the socket, and also of the stock of the crossbow, as shown in Fig. 50. The position of the center hole prevents the pin which passes through the nut from being too near the upper edge of the stock. It also gives the revolving nut more 'center bearing' against its socket to withstand the strain of the bowstring.

The pin is 1/8 in. diameter and  passes through the 3/16 in. hole in the center of the nut and  the lock plates.

The socket should take all the pressure of the nut when the bow-string is stretched over the fingers nut. For this reason, the pin is slightly smaller than the hole in the center of the nut. If any strain any the pin would bend it and the nut would not revolve.

In many Medieval crossbows, the nut was replaced with thin length of catgut passed several times through the hole in the nut, and then round the stock to prevent the nut from falling out of its socket (Fig. 51.) More often, however, the nut was held in its socket by two small screw pins, one through each lock plate, neither of which penetrated the the nut more than 1/4 in. (Fig. 52).

The nut and its socket were formerly both made of horn. 1 Steel nuts and sockets were not generally fitted to crossbows until about 1640-1650. The nut was usually cut from the crown of a stag's antlers. This was a strong and light material that was free and quick in use and loose in its connection with the bowstring. In Scandinavia, walrus tusk was commonly used for the nut of a crossbow. The horn nut always had its notch protected by a small wedge of hardened steel, which met the point of the trigger inside the stock. Fig. 52 shows this kind of nut, and A, B, the front and side view of its steel wedge separate from it.

The center hole of the nut is 14 in. from the upper point of the fore end of the stock (D - C, Fig. 46).

The Trigger and Lock

Fig. 54. - The handle or round part of the trigger, A-A, the outside the stock, is 8 1/4 in. long and 3/8 in. diameter. The flat part of the trigger, A B, which works inside the stock, is 7/16 in. thick. The hole for the transverse pin on which the trigger hinges, is 3/8 in. diameter. The point, B, of the trigger, or the part of it which engages the notch in the nut, is hardened to withstand wear from friction.

The point, B, of the trigger, is 7/16 in. thick and 1/4 in. deep. It should just fit through the opening in the socket, plus  1/8 in., or half its depth, into the notch in the nut, as shown in Fig. 55.

Fig. 55. - When the handle end of the trigger, A-A, is pressed upwards towards the under side of the stock, the point of the trigger (B, Fig. 54), drops out of the notch in the nut. The nut, now being free to revolve, releases the bowstring, which was stretched and previously held fast over its fingers.

The small spring (C, Fig. 55), inside the stock, forces the point, B, of the trigger firmly into the notch of the nut. In this way the bowstring is securely held until the nut is released by pressing the handle of the trigger upwards.

After the fifteenth century, other forms of trigger were invented for holding and releasing the revolving nut. The lock described here was the simplest and best for ordinary use and, until the end of the fifteenth century, was the only one applied to crossbows, whether military or sporting, which discharged bolts.

Fig. 56. The lock plates - one on each side of the stock - are of steel, 1/8 in. thick. The lock plates and their transverse screws hold the nut, socket and trigger in position and strengthen the stock where it is cut out for the nut and its socket.

The lock plates (shaded) are mortised in flush with the woodwork of the stock, and close against the sides of the revolving nut and its socket (Fig. 56.).

The trigger plate is fitted beneath the stock, as per the dotted line and screws.

A. The 3/8 in. pin on which the crossbow trigger hinges.

B. The 1/4 in. pins (5), which fasten the lock plates and socket for the nut.

C. The 1/8 in. pin on which the nut revolves.

These pins all pass fully through the lock plates and the stock, securing the lock of the crossbow to its stock. When the pins are screwed into place, their heads and points should be level with the the lock plates.

In Medieval crossbows, the pins of the lock were always riveted by a hammer at each of their ends after they were driven in. This was, perhaps, a tighter method of fixing them, but was a plan which prevented the lock from being readily taken apart.

The Steel Bow, Bow Irons and Stirrup

The Bow

Dimensions of the Bow (Fig. 58)

Length - 2 ft. 6 in.

Width - At center of length, 1 5/8 in., with a gradual reduction to a width of 1 in. at 2 in. from each end.

Thickness - At center of length, 1/2 in., with a gradual reduction to 3/8 in. at 2 in. from each end. Width across enlarged parts of ends, each 1 1/2 in. 

The bow is flat on all sides, with squared edges.

For the ends of the bow, into the notches for the loops of the bowstring, see Fig. 69.

The normal bend of the bow, taken from the center of its length, inside its curve, to the center of a thread connecting its ends, is 4 1/2 in., C - D, A (Fig. 58.).

B, Fig. 58, shows how the arms of the bow are slightly canted up from its center. If a thread is held from the center of one end of the bow to the center of its other end, as per the dotted line, it should be 1 in. higher at its center than the upper edge of the bow, as the bow lies on its side on a table, x- x, B (Fig. 58.).

If the bow did not have this upward cant, the bowstring would press so hard on the top of the stock that it would be unable to propel the bolt with proper force. The friction of the bowstring against the stock would prevent the string from acting freely when the bow recoiled from a bent position. All the best steel bows were made in this manner.

Many of the military crossbows had straight bows, which were merely canted upwards in their stocks to enable their bow-strings to work freely. However, this did not give so straight a pull and so much strain to the bow, as the one described in (Fig. 58.).

A. Side View, Showing the Normal Curve or Bend of the Bow
B. Full Face View of the Front or Belly of the Bow, Showing How Its Ends are Canted Up from the Center 

To procure a good bow of spring steel of correct size and shape, it should be first modeled in wood. The model should then be sent to a spring maker to copy, with instructions to temper the steel a little soft, so that the bow may take a slight  set, rather than break, if overstrained.

Bow Irons

There are two of these irons, one on either side of the crossbow stock. They are each 7 in. long, 1/4 in. thick, 1/2 in. wide around their sides 1/2 in. wide between the narrow parts of their openings.

The wide openings of the irons, at their large ends are 1 5/8 in. to fit the bow at its center. The irons surround the center of the bow, as well as the corners of the base of the stirrup. The base of the stirrup rests upon the center of the back of the bow. The bow irons act as straps to pull, and hold, the bow and its stirrup tight against the stock of the crossbow, using the metal wedges (Figs. 61, 62, 63).

When the bow, bow irons and stirrup, are in position on the stock of the crossbow, the openings in the bow irons should each be 3/4 in. short of the end of the oblong hole in the stock  next the nut, as shown at E, Fig. 63.

The base of the crossbow stirrup is the same width (1 5/8 in.) as the center of the back of the bow. Its base is 2 in. long inside, or 1/2 in. more than the thickness of the stock, I (Fig. 60). This is necessary to allow space for the bow irons to encircle the corners of the stirrup when the stirrup and the bow are placed in the opening in the forehand of the stock, before inserting the wedged (Figs. 61, 63).

The crossbowman placed his foot in the stirrup, to enable him to hold his crossbow firmly to the ground, while he bent bow with the windlass, or, in the case of small crossbows, as he drew the string to the nut with his hands or by means of a rope and pulley (Fig. 77).

How to Fix the Bow to the Stock

First secure the stock of the crossbow perpendicularly in a vice, its forehand upwards.

Take the stirrup and bow irons together, as shown in Fig. 61 and, with center of the back of the bow being against the base of the stirrup, pass the bow through the irons. Place the base of the stirrup and the bow in the opening (A, Fig. 46), in the forehand of the stock, with a bow iron on each side of the stock.

The angled ends of the short guard fit over the wood of the stock between the sides of the bow irons. Insert the short guard, A, into the oblong hole in the stock next to the bow (Figs. 62, 63).

Next, insert the long guard, B, through the bow irons, against their narrow ends, and through the oblong hole in the stock (Figs. 62, 63). The angled ends of B, turn back over the top of the solid part of the narrow ends of the bow irons, and hold the irons close against the stock. Now push the two wedges, C, D, in between the guards, A, B,  from opposite sides of the stock (Figs. 62, 63). By hammering in these wedges, the bow irons will gradually draw the base of the stirrup, and with it, the center of the bow beneath it, tight against the crossbow stock.

The empty 1/2 in. space (E, Fig. 63) of the oblong hole in the stock is left in case further tightening of the bow is necessary. Tightening is done by fitting a thin metal strip, to act as a washer, at the back of one of the guards.

Before fixing the bow to the stock, ensure it is in the correct position. For the bow to shoot accurately and with full power, requires three conditions:

I. The bow must be immovably fixed in the stock.

II. The arm of the bow on one side of the stock, should be less than 1/8 in. longer or higher than its arm on the other side of the stock. A piece of twine tightly fastened from one end of the bow to the other, with a little bit of colored silk knotted round the exact center of its length is a valuable guide when regulating the position of the bow.

III. When the bow is fixed, a thread of cotton stretched from the center of one end of the bow to the other, should be in a straight line and not pushed up at its center by the surface of the stock.

The thread should cross 1/4 in. above the stock, so that when the bowstring, which is 1/2 in. in diameter, is fitted to the bow, the lower edge of the string will just lightly touch the groove in which the bolt is laid so there will be no friction to retard the force of the bow-string when the crossbow is discharged.

The Groove for the Bolt

The groove (13 1/4 in. long, 3/32 in deep in its hollow) may be of brass. It reaches from the forehand of the crossbow stock to the metal socket which holds the revolving nut (Fig. 64.).

The short (3/4 in.) length of  the section  of the metal socket which is in front of the nut, is recessed to correspond with the long separate grooved piece which comes up to it (Fig. 64.).

The groove should be neatly and tightly mortised in flush with the surface of the stock (Fig. 65.). It should have two, or three thin pins to secure it from slipping forward, and will have to be as smooth as glass and as true as a gun barrel from end to end.

In many old crossbows the groove for the bolt was of horn, and glued into its mortise on the top of the stock. This was a lighter method and is one to be recommended if a suitable piece of horn is available.

The Crossbow String

The crossbow string should be composed of several dozen turns of thin twine, of pure hemp or flax. Sailmakers sewing twine is excellent for the strings of large crossbows, as it is very strong and will not stretch under the great strain of the steel bow. Any twine in the form of soft twisted string is sure to stretch and, what was at first a taut bow string will, if this kind of material is used, soon become slack and useless.

I, II  An auxiliary loop of fine thread passes between the halves of the bowstring.

III, IV  The two loops lashed together so as to jointly form one end of the bowstring.

In some Medieval crossbows, the bow-strings were strengthened at their ends in a very ingenious manner by means of auxiliary loops. How this was done is shown in Fig. 66.

How to Make the Bow-String of a Crossbow which Shoots Bolts (Fig. 67).

Hammer a round peg of hard wood (4 in. long, 1/2 in. diameter) firmly into a hole drilled through a board  3 ft. in length, by 6 in. wide and 1 in. thick. The hole for the peg should be 3 in. from one end of the board, and the peg should be set perfectly upright.

Place the notch at one end of the steel bow level with this peg, then fix a second peg in the board  1/2 in. short of the notch at the other end of the bow. The measurements should be taken from the outside edges of the pegs. This will give you the correct length of the bow-string.

Next, wind the fine twine evenly round and round the two pegs in the board, being careful not to cross the threads between the pegs until you have a smooth tight skein (A, Fig. 67). Continue wrapping the skein halves together until, when piece of twine, wrapped around the center inch of the skein, results in pulling the skein to a diameter of 1/2 in.

Now rub beeswax all over the skein until its threads stick together. This will make the bow-string impervious to water or damp and will preserve it indefinitely.

Without removing the skein from the pegs, wrap a long well waxed length of strong silk - in turns 1/8 in. apart around its entire length, and a little closer (by the aid of a darning needle) at its ends where they pass round the pegs (B, Fig. 67). Without this wrapping, the skein is sure to fail (especially at its ends), into a hopeless tangle during the process of converting it into the bow-string.

Using some hard twine, tightly wrap the skein (or bowstring as it may now be called), as shown in C, Fig. 67.

The center wrapping, which lies above the groove in the stock, is 4 in. long and the end wrappings are each 3 in. long. The center wrapping may be overlaid at its center, for 1 in., with a little crimson silk, to show the exact center of the bow-string, so should the bow shift in use, the movement can be detected and the bow re-adjusted in the crossbow stock.

The loops at each end of the bow-string should be wrapped, if possible, without removing the skein from the pegs in the board. If this cannot be achieved, on no account lift the skein off the pegs till the center and end wrappings are completed.

When the bow-string is finished, the silk can be removed where it shows between the wrappings.

How to Fit the Bow-String to the Bow

The bow-string is 1/2 in. shorter than the space between the notches of the bow and will not reach from one notch of the bow to the other. Otherwise, the bow-string would not be taut when the bow is strung.

To place the loops of the bow-string over the notches in the ends of the bow, mechanical aid is necessary. It would be quite difficult to bend a thick steel bow for this purpose by manual power alone.

To fit the bow-string to a crossbow, use a bastard string The bastard string - by means of the windlass of the crossbow (Fig. 76) - bends the steel bow sufficiently to allow the loops of the bow-string to be slipped into the notches at the ends of the bow (Fig. 70.).

The bastard string is then removed from the bow (Fig. 71.).

The bastard string (constructed similar to the bow-string) is temporarily fixed to the arms of the steel bow by two small iron screw clamps (Fig. 70.). It hung loosely when the clamps are attached near the ends of the bow. The windlass is used to pull the bastard string tight down over the fingers of the nut, and held while the bow-string is fitted (Fig. 70.).

By regulating the position of the clamps on the  bow, any crossbow can be bent by its windlass just enough to remove and replace the  bow-string.

To remove the bastard string (after having fitted the bowstring into the notches of the bow), do not pull the trigger of the crossbow. Hold one handle of the windlass with one hand and press the trigger at the same time with your other hand, then let the bastard string gradually slacken and the bowstring tighten as you reverse the windlass.

The fitted bow-string should be from 1/2 in. to 3/4 in. further along the groove in the stock, towards the nut, than a thread would be, if stretched between the ends of the bow at rest prior to installing the bow string. In this crossbow the front of the string should be 5 in. from the inside upper edge of the center of the bow, and the back of the string, 6 in. from the center of the nut.

If the fitted bow-string is a slack, take it off the bow by means of the bastard string. Undo the center wrapping, give the string two or three twists to shorten it, then replace it on the bow and wrap its center again.

If the string is too tight, and bends the bow too much, there will be a waste of power and  a risk of fracture when the bow is fully bent by the windlass.

A bow string which is 1/2 in. too long, can be set right, but a string which is 1/2 in. too short is beyond remedy. If the bow string is too short, unwind the skein and remake it longer.

The crossbow is now complete, with the exception of its windlass. It should appear as in Fig. 72, with its woodwork smoothed and nicely stained, and its metal fittings hardened and polished. The sharp edges of the stock can all be rounded off slightly, excluding the opening in which the bow and its stirrup are fitted.

The Crossbow Windlass

The sheath of the handle end of the windlass fits over the small end of the stock of the crossbow, as shown in Fig. 73. In the surface view, only the ends of the cords are inserted, to avoid confusion of detail. The end of the sighting strip is also omitted in this view for clarity.

Fig. 74. In the surface view, the pulley cords are not given, in order to show more clearly the arrangement of the wheels and of the guards which keep the cord in position on the wheels. See Fig. 75 for the windlass in position on the crossbow.

To draw the bow-string of a powerful crossbow to the nut, a windlass or cranequin is necessary. Though the distance which the bow-string has to be pulled along the top of the stock is only 5 or 6 in., no manual strength could draw it half-way.

The stooping figure has a windlass crossbow, and is winding up the bowstring of his weapon. The erect figure carries a crossbow that is bent by the metal claw, which may be seen hanging from his belt.

A crossbow windlass, small as is, has immense power and will draw the bow-string to the nut smoothly, quickly, and with no perceptible strain or exertion.

To use the windlass, the sheath of its handle end is fitted over the small end of the stock, and the claws of its forehand are hooked over the upper surface of the bow-string, as shown in Fig. 75.

In Fig. 76, the bow is bent, but the windlass is not removed, its showing proper position on the stock and string .

By reversing the handles of the windlass a couple of turns to slacken its cords, it can be quickly removed from the stock of the crossbow, which is then ready for use. In former days the crossbowman, after he had stretched his bow-string and removed the windlass, suspended the windless from his side, by means of a hook attached to his belt.

Fig. 77 shows a crossbowman using his windlass to bend his steel bow.

He holds a bolt between his teeth so it is  ready at hand to place on the stock of his crossbow once its bow is bent. 

The Bolt, or Quarrel, and How It was Arranged on the Stock of the Crossbow

Dimensions

Total Length - 12 1/2 inches.
Length of head - 3 inches
Diameter of shaft at C, near where it meets the sheath of the metal head - 11/16 of an inch.
Height of the shaft at its butt end - 1/2 inch

The weight of the bolt is 2 1/2 oz. (shaft 1 oz., metal head 1 1/2 oz.).

The butt of the shaft, for about an inch, A - A, is slightly flattened at opposite sides (in line with the side feathers) and then tapered to a width of 3/8 in. (Figs. 78, 79). This allows the butt to fit between the fingers of the nut and against the bow-string, as shown in Fig. 82.

The butt of the shaft, being tapered as well as flattened, can be gently wedged in between the fingers of the nut to prevent the bolt from slipping forward when the crossbow is aimed towards the ground. The head of the bolt is greater in width than height (Fig. 80.). 

The head is shaped so that it might not touch the groove of the stock, and cause friction or divert the direction of the bolt when it is propelled by the bow.

The bolt should lie with only the enlarged fore end of its wooden shaft (C, Fig. 78), and its butt resting on the groove of the crossbow.

The side edges of the head of the bolt should be in line with the side feathers of the shaft, and the upper edge of its head, - as the bolt lies in the groove on the top of the stock, - in line with the top feather of the shaft. One edge of the head of the bolt will be upright, to act as a long and fine fore-sight.

Before bending his crossbow, the crossbowman revolved the fingers of the nut downwards into its metal socket, in the direction of the bow (Fig. 81.). When the bow-string was drawn along the groove of the stock by the windlass, it contacted the  flat surface of the nut at A and rotated the nut around into the position which caused its notch to engage the point of the trigger inside the stock and secure the bow string behind the nut. The bow string was held fast until the trigger was pressed to discharge the crossbow.

Figure. 83. This curious variety of bolt was shown me by Col. Henry Walrond, the noted authority on Archery. I find that bolts made in this manner fly with great accuracy and force. They were, however, intended for the target and not for warfare, for which purpose a longer and heavier missile would be necessary. In the latter case, the flanges would require to be of a size that would prevent the bolt being used in a crossbow.