Correlations between Grain Angle Meter Readings and Bending Properties of Mill-Run Southern Pine Lumber

Metriguard's grain angle meter (Model 511) measures grain angle in wood by assessing permittivity. This study evaluates the correlations between grain angle meter readings and bending properties of 1,400 kiln-dried 2 by 4 specimens of southern pine (Pinus spp.) lumber and considers its utility for providing supplementary data for predicting the strength of lumber. The results showed that in mill-run lumber, the correlation between grain angle and modulus of rupture (MOR) was -0.420. In addition, in graded lumber, the correlation between grain angle and MOR got progressively stronger as the grade went down. With a few technical modifications, applying this device in a mill production setting could prove useful for supplementing other nondestructive methods for assessing bending strength in lumber.