Portable E-Tester for Selecting Structural Component Lumber

Because the stiffness properties in any given grade of structural lumber are based on the average stiffness of that grade, the modulus of elasticity (MOE) E-Tester described in this article was developed. This apparatus is intended to assist a structural component fabricator to sort out the stiffer pieces for specific uses such as the bottom chords of parallel chord floor trusses. To verify the accuracy of the equipment, 545 randomly selected pieces of 2 by 4 stress-rated, No. 2, kiln-dried, Southern Pine lumber, were tested and compared to the results of the same pieces tested on a commercially available E-computer. The data show half had an MOE below the average for the grade (1.6 x 106). Design procedures for structural components assume the MOE to be the published values. Therefore, some pieces will be below the average. Verification by these two methods has shown good agreement and reliability for sorting out the stiffer pieces to meet the design criteria.

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