[Display omitted] • Hardwood strength grading is challenging due to a lack of clearly identifiable defects. • Detection of local fibre deviation enables a strength profile along the board. • 3D local fibre direction can be used as a prime indicator for the tensile strength. • Data on European beech indicates a very large natural scatter in mechanical properties. • Automated laser dot scanning can be used for the prediction of the fibre deviation. In central Europe forests, the share of European beech (Fagus sylvatica L.) trees has been increased in the last decades. Machine strength grading of hardwood is challenging due to a lack of knowledge about strength predictors. However, high strength classes are needed for the utilization as glued and cross laminated timber. We used the information of an industrial scanner on fiber orientations, developed a 3D cluster value (SOG 3D,150,max) for strength assessment and combined the parameter with the dynamic modulus of elasticity (MOE dyn) to compute an indicating property (IP). A sample of 407 European beech boards passed a multi-sensor scanner to detect wood density, eigenfrequency and slope of grain (SOG). Fiber angle on the surfaces of four board sides was measured using the tracheid effect. The spatial fiber orientation inside the board was modeled for a total of approximately 150,000 points per board meaning 12 points per cm3. Finally, the board section with the largest average local fiber orientation in a window of 150 mm defined the grading parameter SOG 3D,150,max. The prediction of tensile strength via SOG 3D,150,max reached r2 between 0.466 and 0.605 depending on the type of data transformation. A combination with the MOE dyn , the probably most common IP , increased the r2 to 0.722 at best. Local grain deviation is a suitable wood parameter for hardwood strength grading. By detecting local defects, the causality between wood strength and tree functioning as well as silvicultural steering may be further understood in future. [ABSTRACT FROM AUTHOR]