What happens when a bow breaks? Opening up your case to a broken bow or having the head pop off mid stroke can be quite traumatic. Or maybe you fumbled the bow, unable to recover it before it strikes the floor. Though damage to the head is extremely devaluating, it may be possible to fix it for use once more.
The following outlines the procedure for a headspline which reinforces a broken head with a thin strip of pernambuco inserted in the opposite direction of the grain in the stick. This type of repair when executed well can last indefinitely and restore many, if not all, the playing characteristics of the bow
Gluing the Head
The hair is removed from the head. Both surfaces on either side of the damage is cleaned and the head is glued back together.
Slitting Saw Operation
The bow is mounted in a mill or lathe and using a thin slitting saw, a circular groove for the spline is cut. This video was sped up, but the saw blade is moving at a relatively slow speed with the teeth coming down through the top of the head.
Preparing the Spline Material
The pernambuco spline material is closely matched to the color of the stick. The wood is planed to thickness and shaped to match the width and radius of the groove.
Gluing the Spline
The spline is then glued into place across the grain and allowed to completely cure before proceeding to the next step.
Shaping and Finishing
The excess spline material is trimmed down with a knife and then dressed with files. It is finished with a dye, light sanding, and French polish. When done correctly, this repair can be difficult for the untrained eye to detect. The bow is now ready for hair!