According to a handbook distributed by the US Forestry Service and the USDA, many lumber mills fail to saw to lumber to improve its grade, and thereby reduce their own potential profitability. Following a few principles regarding the sawing, edging and trimsawing of lumber can see overall improvements in the grade yield of mill-produced lumber.
Examine the log for defects. Defects on logs include knots, holes, rot, softened hardwood and bumps, and often affect the grade of the finished lumber. If you believe the log to have an insect infestation, fumigate it thoroughly before introducing it to the mill.
Position the log so that the majority of defects rest on the sides, rather than corners. Placing defects on sides subjects them to easy trimming, and can significantly improve the grade of lumber milled from logs with considerable defects.
Saw the poorest side of the log first whenever possible. This provides bearing for sawing the better faces, and will speed up taper sawing processes by eliminating the need to set up the opposing good faces.
Saw poor faces only lightly to avoid robbing grade lumber from good sides. Turn the log for sawing before grade is lost, maximizing the amount of salvageable lumber.
Saw good faces deep, until the grade drops to that of adjoining faces. Turn the cant, or squared log, and saw the next best face, repeating until the cant is too small to saw. This practice will keep sawyers from oversawing poor sides and losing marketable lumber.
Saw logs that have deep sweep so that the entirety of the bow in the lumber can be removed in one cutting. This also reduces the remaining amount of wane on the lumber.
Saw logs with spiral seams, with the seam-side noted as the poor side, and saw once, lightly, to provide a firm bearing before sawing the good sides. Return to the poor side to saw for grade only after the other three sides are complete.
When edging, allow for wane within the FAS (First and Second) grade limits. In many cases, it is more profitable to edge too wide and lose a grade, than to edge too narrow and loose both a grade and a scale.
Do not discount partially rotting or long-dead lumber; in some hardwood species, trees can be dead or fallen for years (even decades) and still retain milling value.
Practice applicable safety procedures when handling logs or operating saws.