Analysis of Yield of Dimension Stock from Standard Lumber Grades

Data collected from the rough-end department of a woodworking plant can only predict the yield currently obtainable from various factory lumber grades, not necessarily the full potential yield. In this study a computer was used to determine the influence of length, width, and grade of cuttings on the yield of various lumber grades. The computer examined 12,569 board feet of lumber representing a mixture of five species and four standard lumber grades. A weighting system capable of altering the emphasis on the length of cutting was incorporated into the program. The data were processed by the maximum-yield weighting system and the longest-length weighting systems only. Cutting groups processed by the maximum-yield method give figures that reflect the maximum possible yield regardless of the distribution of cuttings among the individual target lengths. The target lengths were selected to give the widest possible range of lengths that would allow farily accurate predictions of yield for other target-length combinations. The influence of grade of cutting, of the weighting system, of the target length, and of width on yield were examined, and the basic relationships between the standard lumber grades and the size, grade, and methods of cutting were detailed. There was little difference in yield between the following grades of cuttings: clear two sides, clear one side, sound reverse side, and sound two sides. Within a standard lumber grade, the extent of the decrease in yield was determined for increasing length of cutting, the lower the grade, the more rapid the decrease in yield with increasing length. As the width of cutting was increased within a given standard lumber grade and target length, the decrease in yield was determined; the lower the grade, the greater the decrease in yield, for any given width. The longest-length system concentrates the yield in the longest cuttings and considerably reduces the yield of secondary cuttings, as well as the total yield, allowing estimates of the maximum amount of long, clear cuttings available within the various standard lumber grades. The maximum-yield system gives an estimate of the distribution of clear cutting sizes available within the various grades. The influence of board length on yield was especially strong when the target lengths were whole number multiples of the board length.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member