Effects of Three Sawing Methods on Warp of Hard Maple Dimension Cuttings

Three 10-log groups of hard maple were sawed into standard 4/4 lumber by three methods 1) a recognized hardwood grade-sawing method of sawing-around-the-log; 2) a modification of the recognized grade-sawing method; 3) a live-sawing or through-and-through sawing method. The lumber was presurfaced green, kiln-dried, and then ripped and crosscut into rough, small dimension cuttings clear of defects. Warp, as such, was not considered a defect. The sizes of the rough clear cuttings were based on a predetermined schedule in line with practices at woodworking plants: 1-1/2 inches to 5-1/2 inches wide and 12 to 44 inches long in 1/2-inch increments of size. The rough cuttings were fed through a conventional facing planer-cabinet planer setup, planing the cuttings to a finished thickness of 13/16 inch. Prior to the planing operation, the cuttings were lightly spray coated with a green lacquer to permit ready identification of areas skipped because of warp. Analysis of warping was based on the recovery of warp-free cuttings and the area measurements of the cuttings, related to log scale, lumber scale, and rough clear-cutting areas. Total area of skips on all planed pieces as related to the rough cuttings was also analyzed. Pieces having skip were subjected to simulated remanufacturing in line with predetermined schedule and these data analyzed. The live-sawing method produced a greater area of rough clear cuttings. However, when the rough clear cuttings were planed to the 13/16-inch finished thickness, the grade-sawing methods produced a significantly greater area of warp-free clear cuttings than the live-sawing method. There was no significant difference between the grade-sawing methods. From the standpoint of waste due to warp only (original dry lumber basis) the grade-sawing methods resulted in losses of 36 and 35 percent and the live-sawing method 50 percent. Loss due to defects amounted to 40 and 37 percent for the grade-sawing methods and 34 percent for the live sawing method. The total waste loss for defects plus warp in producing the clear, warp-free finished cuttings amounted to 76 and 72 percent for the grade-sawing methods and 84 percent for the live-sawing method.

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