Sawmill managers are interested in carrying out the sawmilling process in an efficient manner with minimal waste of raw material. In primary processing, an increase in productivity can be achieved if the process can be controlled. This can be achieved by developing a macro-mechanic model of the cutting power determination considered from a point of view of modern fracture mechanics has been developed. For the model knowledge about fracture toughness and shear yield stresses is vital. Pine wood (Pinus sylvestris L.) is a popular species which is widely used in wood industry in Poland and Sweden. Test samples with a cross section of 70 × 70 mm were originated from the both countries. Before sawing, all wood samples were scanned on X-ray Computed Tomography in laboratory conditions in Skellefteå (Sweden). These CT scans were helpful in indicating where clear and knotty samples were obtained from beams. Cutting tests were carried out on the custom-made laboratory stand in Skellefteå. The rotating arm held the wood sample, and the cutting speed equaled 15.5 ms−1. A stellite tipped tooth was fed into the wood sample with uncut chip thicknesses for clear wood 0.5; 0.7 and 1.1 mm, and for knotty wood 0.3; 0.5 and 0.7 mm. The tooth data: overall set equal to 2.9 mm, rake angle 27°, and clearance angle 12°. A piezoelectric sensor on the tooth holder measured the cutting forces. On the basis of the experimental findings it is possible to create mathematical models cutting forces for clear and knotty pine wood. For knotty wood the intercept is almost twice than for clear wood.