Drill a blind hole across the crack with the appropriate drill size (#49 typically). Clear the hole of chips. Insert the rod marking the circumference where it exits the hole. Spinning the rod in a bench motor, scribe the rod at the pencil mark with a jewelers saw to a depth equal to approximately 1/3 the diameter of the rod. Place 3 drops of CA glue into the hole. Insert the carbon rod. Break off the rod at the scrib line. You’re now read to finish up with wood dust and CA.