Finger Jointing At High Moisture Content

Scarf joints and finger joints were machined in Douglas-fir lumber that ranged from 8 to 23 percent in moisture content. The effect of drying stresses was evaluated by subjecting end-glued studs to various degrees of seasoning before subjecting them to static-bending tests. The tests of scarf and finger-jointed Douglas-fir studs indicated that studs with 1:6 scarf joints glued with combinations of 20 and 14 percent moisture content appeared to suffer no loss in MOR as a result of seasoning to low moisture content prior to static-bending tests. The average MOE for scarfed studs was lower than expected. Studs finger-jointed from either conditioned or unconditioned kiln-dried pieces suffered losses in MOR ranging from 19 to 28 percent when glued at high moisture content and seasoned to low moisture content before testing. Average MOR for finger-jointed studs compared favorably with average bending strength for Construction end Standard grades of Douglas-fir 2- by 4-inch dimension lumber. For most finger-jointed pieces, MOE exceeded the traditional average for clear Douglas-fir. Finger-jointed studs possessing strength adequate for many uses can be made from clear lengths of kiln-dried Douglas-fir at moisture contents of 14 to 20 percent.

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