Cracked Neck and Headstocks
What Causes Cracks in Necks and Headstocks?
Impacts with foreign objects are typically the cultprate in damage sustained by headstocks and necks. There are a few scenarios in which methods, materials and supplies used during construction cause such problems, however, most of those construction related issues have been long since refined out of the processes involved in fabricating a neck by the major manufacturers.
Impacts with foreign objects (whether the guitar is in its case or not) will often crack necks and headstocks because of the load of string tension carried by the neck. On a one piece neck, as is seen on many Martin and Gibson guitars, cracks typically occur at the headstock because the grain orientation changes there. The length of a one piece neck has a grain orientation which provides strength to the length of the neck from the nut to the heel. In this portion of the neck the grain runs parallel to the fretboard. However, as the headstock angles back the grain orientation is no longer ideal. Instead of the grain running parallel to the top and back of the headstock, the grain runs across the headstock at a slight angle (+/- 20 degrees). This is not ideal for rigidity. Many manufacturers join a second piece of wood to the neck to serve as the headstock using a finger joint (such as Taylor Guitars) or a scarf joint (Alvarez). This method of construction allows for the ideal grain orientation at the headstock to resist cracks from impacts with foreign objects.
How is a Cracked Neck or Headstock Repaired?
There are many factors that determine the method of repair used in repairing a cracked neck or headstock including budget constraints, collectability, previous repair etc… An adequate first line of defense for repairing a cracked neck or headstock is to simply glue the crack with hide glue. This may be done with or without a touchup. This repair is not always permanent, however it can easily last for many years (assuming no future impacts with foreign objects occur).
More in depth cracked neck or headstock repairs involve reinforcing the repaired area. This may be done in many ways. Two approaches we commonly take to reinforce such a repair are to hide graphite composite rods beneath the faceplate or remove wood from the back of the neck and headstock in order to install new wood spanning the crack (frequently referred to as a “backstrap overlay”).