what is the core for?

[stuckinthemud]

Hi All, I've been reading various old threads on PA on horn composite bows and it appears that the main attribute of a core-wood is to resist shear?  It also seems that many cores are damaged by the extreme stresses imposed on them but that the bows continue to function, presumably because the components that do the work are the horn and the sinew.  Is the job of the core, then, more of a scaffold, preventing twist, giving shape, and providing a good glueing surface for mating the horn to the sinew?

[loon]

+1
I don't get why the core needs to be thicker for heavier bows, or something. Of course those native american horn bows have no core... Don't know if one could do V-splices with no core.

[BowEd]

It provides stability to the bow.Preventing twist.

[Badger]

     Besides the things mentioned above core woods are much lighter than horn and sinew. It primarily acts as a lightweight spacer between the working surfaces. The thickness determines how stiff the bow will be.

[dragonman]

if the thickness of the core afects the strength or stiffness of the bow, then it is obviously doing something! its not just a spacer. I have made a couple of horn bows and bows with bamboo replacing the horn, I have tried different cores and the stonger denser core woods appear to add draw weight and work better....I believe the core wood does roughly a third of the work, therefore a strong bow needs a strong core to be efficient and the increase in physical weight is negligable