That´s a typical medieval crossbow. Its bow is made of horn, backed with 2- 3 layers of sinew, wrapped with sinew and covered with birchbark. The bent ends or recurves of the bow are made of another spliced in piece of horn or antler. These crossbows are told to draw 150- 300lbs. The bow measures in length 30″ – 35″, at the handle width is 2″, at the ends( just where the recurves are beginning) width is 11/2″, thickness is about 3/4″ at the center tapering down to 1/2″ at the ends. The recurves are measuring about 31/2″ in length.
The horn slats are assembled like the stones of a dry stone wall, no running through seams or joints. It would be no problem to use thinner horn slats, it depends on the available material, so their could be 7 rows of horn slats adjoined. The lengthwise joints are butt joints at a 45 angle.
First is to glue the orange slats, then insert the black slats, last add the red and green slats to the sides. So there are 5 rows of slats. The back of the assembly of horn slats will be cut even, rasped to an even thickness and width, than the tapering in width and thickness has to be done. The rectangular cross- sections will be rounded more towards the belly of the bow. Time for a first test of tiller(even bending), drawforce, any sounds of breakage??.
In the drawings of the cross-sections the sinew- backing is marked blue.
The cross- section at the left is another way to do a hornbow for a crossbow. Just glue at least 2 slats together lengthwise one upon the other and sinew- back them. This is an easier way. But it is not recommended for really high drawweights up to 200- 300lbs……………..and it´s hard to find horns measuring such long enough with a roughly even required thickness. The dry stone wall method makes a more effective use of the entire horn.
Next volume is focused on the next step of the making of the “dry stone wall”, and I hope so, on sinew- backing in general.