A model for the sawing and grading of lumber according to knots

As a means to determine the grade improvement potential of black spruce, a sawing and grading model is presented. It uses an analytical representation of the knots, the boards, the log, along with the National Lumber Grades A uthority Visual Strength Grading Rules, as a means to grade the sawn lumber according to the knots. A simulation was performed using knot data collect ed on the surface of a black spruce log. The log was then sawn, and the dat a were collected on the board surfaces. The simulation shows that, in gener al, the model approximates well the knot diameter on the boards using data collected on the log's surface, but the "equivalent diameter" as calculated from the NLGA Rules underestimates it.