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The Resonance Lumber Grader estimates the dynamic MOE【calculated as the product of density and stress-wave velocity squared】. Stress wave velocity is measured by longitudinal vibration. It is a good predictor of lumber quality.

The Resonance Lumber Grader is a simple tool. It consists of a hammer and an Android phone or tablet with a specialized software. The user enters the length, select species. Lumber Grader is using the nominal density of selected species, user can overwrite the given density value. After hitting the end of the lumber grade appears on the screen based on EUROCODE338. Because of the uncertainty of the density the grade is informative only.

1. Set the length of the lumber. Choose specie and/or set density.
2. Hit the end of the lumber with a hammer (100g).
3. Read the calculated velocity and grade appearing on the screen.