Grading and properties of small-diameter Douglas-fir and ponderosa pine tapered logs

Approximately 375 Douglas-fir and ponderosa pine logs, 3 to 6 inches in diameter, were tested in third-point bending and ill compression parallel to the grain. The moisture content at time of test was about 14 percent. Good correlations were found between the Modulus of elasticity (MOE) ill static bending and those obtained by transverse vibration. Good correlations Were also found between modulus Of rupture (MOR) and MOE. A species independent relationship was established between ultimate compression stress parallel to the grain and MOR. A mechanical grading system previously developed for 9-inch diameter logs was shown applicable to small-diameter logs.