Truss rod — What does it actually adjust?

The truss rod is the rod inside the neck that helps control its curve, known as relief. That slight curve gives the strings room to vibrate without touching the frets where they shouldn't.

A change of string gauge, a different tuning and changes in the environment can all affect relief. Still, a buzz doesn't automatically mean the truss rod needs adjusting: the nut, the bridge or the frets may be to blame.

Adjusting it takes measurement, the right tool and knowledge of that particular mechanism. If there's heavy resistance, we stop. The truss rod doesn't fix every problem, and too much force can cause serious damage.