A Conjectural 12th/13th Century Crossbow

Construction

• Material: Ash
• Dimensions: 32 inches long, 1.5 inches wide, 3 inches deep (maximum)
• Draw length: 8.5 inches.

Even given artistic licence, manuscripts consistently appear to show two distinct shapes of tiller:

• Uniformly tapered,the lower edge being more or less straight, with the ticker emerging half way along.
• Similar to the above, but with more depth below the roller mechanism (nut). The ticker emerges from the rear of this area.

The latter design was opted for.

The main problem with a roller lock is how to cut the recess (saddle) in the tiller for the roller. The recess is slightly more than half a cylinder, which prevents the roller from falling out. Such a shape is very difficult to cut accurately, even with modern tools. In later designs, horn or antler inserts for the front and rear were cut to match the roller, and then inserted into the tiller, which means the exercise becomes less problematic. In order to get round this, the saddle was drilled from the side with a hole saw for accuracy, and a side panel of ash was recessed into the tiller. The slot for the trigger arm was bored into the base of the saddle from the lower edge of the tiller, then shaped with chisels.

The track for the bolt was cut by hand with a gouge, and finished with sandpaper wrapped around a bolt shaft. A round hole was bored a the front of the tiller to accomodate the bridle.

• Material: hickory backed lemonwood (aka dagame)
• length: 32 inches
• Dimensions:
  • At centre: 32mm wide x 17mm deep
  • At tips: 23 mm wide x 9 mm deep
• Brace height: 2.5 inches
• String length: 30.5 inches
• Draw weight: originally about 120 pounds at 8.5 inches draw, now about 100lbs (see below)

As with the constrcution of any wooden bow, the prod needs tillering, and exercising to "teach the wood to bend". This is accomomplished using a tillering board (see any book on bow construction for detail) scaled down for the short size and draw length of the prod. Especially in the case of higher poundage prods such as this, it can be a problem to get the thing bending intially - I have resorted to supporting the ends on wooden blocks and using full bodyweight at the centre via a carefully placed foot.

Failing to adequately exercise the prod will inevitably result in it breaking at some point when drawn - been there, got the T-shirt.

Release Mechanism The roller nut was hand filed from the crown (base) of a piece of antler. Due to the size of the available antler, the nut is slightly on the small side (dia x width). A wedge shaped sear of hardened and tempered steel was inset into the base of the nut for the trigger (tickler) to bear on to prevent wear (a little non-period araldite was used to fix this in place). The fingers at the top of the nut hold the string, with the back of the bolt being placed between them. There is no pivot through the centre of the nut - it just sits in the saddle. Tickler Forged from 10mm square iron bar in what is basically a "Z" shape. with a 5mm steel pin through the upper bend of the "Z" to provide the pivot. The action was slightly loose - couple of washers either side of the ticker were used. There is no reinforcement of the tiller around the pivot, no springs ae used in the mechanism. As the tickler is pressed, it disengages the sear underneath the nut, the nut can then rotate, allowing the string to more forward.

Roller lock in cocked position	Roller lock prior to cocking, sear just visible

This attaches the prod (bow) to the tiller (stock), and is made of jute string - as many turns as was needed. The bridle can loosed slightly in dry air, but a little water causes it to tighten.

Forged from 10mm square iron bar. I tried to forge weld the two ends, but failed miserably - a steel rivet is hidden under the bridle. Very proud of the decorative twist!

About 50 turns of "Barbour No. 18" Irish linen thread. Breaking strain per strand is about 18 pounds.

None - put one foot in the stirrup, draw back the string with two hands over the nut, and (if you're lucky) the ticker will engage the sear and lock. Some initial experiments with a single hook spanning belt resulted in a broken prod, the replacement prod having a lower draw weight of 100lbs at 8.5 inches.

Three types have been used, all about 13.5 inches long, made of 11mm pine dowel.

• Archery Centre heads - weight about 2 ounces.
• Dale bolts - later period 14th/15th century bolts with narrow tanged heads
• Rubber blunts (though this bow will probably be considered by most as being too powerful for re-enactment battlefield use unless for VERY carefully scripted longer range shots).

Sighting using the tip of the bolt head, the aim is low by about about 2 feet at thirty yards, point blank at fifty. The bolts will easily pierce a shield at 50 yards (or go an inch into the sandstone backstop if you miss!) Originally, the nut had a tendency to leap out of the saddle when fired, especially when used with lighter bolts. A period solution of a binding consisting of two turns of (artificial) sinew through the centre of the nut has solved this, and also any tendency for the nut to jam in the saddle when being rotated to the cocking position.