The Drying of Predrilled Aspen Lumber

Both 1-inch and 2-inch thick green aspen lumber was predrilled parallel to the wide face prior to kiln-drying. One-quarter inch and 3/8 inch diameter holes were used in the 1-inch boards. The holes drilled in the 2-inch lumber were of 9/16 inch diameter. Hole spacings of 4 inches and 6 inches were employed. There was a reduction in drying time due to predrilling of about 35 percent for both thicknesses of lumber. At an average moisture content of about 6.0 percent the 2-inch pieces with a hole spacing of 4 inches on center were evaluated for moisture content uniformity. The range in moisture content for individual ovendry sections cut from the 5 – 2 by 8’s (97 ovendry sections) was 4.8 to 9.1 percent. At the same duration of drying the end-matched controls had an average moisture content of 18.8 percent and a range of from 8.0 to 40.5 percent. Two-prong stress analysis sections cut from the 1-inch lumber showed reduced casehardening in predrilled boards. In 1-inch lumber also, predrilled boards shrunk less in thickness and more in width than the matched undrilled boards.

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