Grading Knots Away From the Edge
Learning to grade edge knots and combination knots in dimension lumber takes a fair amount of study and practice. These type knots most often limit the grade of a piece. Once the grader has a complete understanding of how these knots are measured and limited it becomes a matter of closely judging the size of what you see and comparing this to a known limit for a known knot size. This makes it relatively easy to estimate the size, and grade accurately on edge and combination knots.