A cutting guide structure (34) arranged at base (5) drives a cutting tool to sectional plane. The cutting guide structure has cutting guide element (8) that is tilted relative to base by a tilt mechanism for angular adjustment of sectional plane. The tilt mechanism includes rectilinear guides (24,29), and slides (25,30) that are linearly moved along the guides in the longitudinal direction. The slide is moved along guide section during displacement to active portion, and the guiding grooves (26,31-33) are formed in guide section and active section.
