A knife assembly for cutting a substrate during relative motion between the knife and the substrate, the assembly including a knife having a distal knife blade and a proximal knife shaft attached to a holder rotatable about a first axis perpendicular to the substrate to define a cut direction angle. The holder is also configured to rotate the knife blade about a second axis perpendicular to the first axis to form a notch angle relative to the first axis. The notch angle is preferably automatically infinitely adjustable within a range of angles. The holder may also, optionally, be configured to rotate the knife blade about a third axis perpendicular to a plane defined by the knife blade to adjust an angle of attack of the knife blade relative to the substrate.

A method of machining a cellular core (14) includes mounting the core (14) atop a table (12) in a multi-axis Computerized Numerical Controlled (CNC) machine (10). The machine (10) is operated to self-scan the core (14) and self-recognize individual cells (30) arranged laterally in columns and longitudinally in rows. A machining path (E) is self-generated from the pre-recognized cells (30), and the core (14) is then machined along the self-generated machining path (E).

A numerical controller according to the present invention includes: a turning condition designation unit that designates a machining condition of turning; a nicking condition designation unit that designates a machining condition of nicking; a fixed cycle instruction analysis unit that generates an instruction sequence of a turning cycle operation based on the turning machining condition; and a nicking operation instruction generation unit that generates an instruction sequence of a nicking cycle operation based on the turning machining condition and the nicking machining condition. The numerical controller executes the instruction sequence of the nicking cycle operation before executing the instruction sequence of the turning cycle operation.

A method of machining a cellular core (14) includes mounting the core (14) atop a table (12) in a multi-axis Computerized Numerical Controlled (CNC) machine (10). The machine (10) is operated to self-scan the core (14) and self-recognize individual cells (30) arranged laterally in columns and longitudinally in rows. A machining path (E) is self-generated from the pre-recognized cells (30), and the core (14) is then machined along the self-generated machining path (E).

A numerical controller according to the present invention includes: a turning condition designation unit that designates a machining condition of turning; a nicking condition designation unit that designates a machining condition of nicking; a fixed cycle instruction analysis unit that generates an instruction sequence of a turning cycle operation based on the turning machining condition; and a nicking operation instruction generation unit that generates an instruction sequence of a nicking cycle operation based on the turning machining condition and the nicking machining condition. The numerical controller executes the instruction sequence of the nicking cycle operation before executing the instruction sequence of the turning cycle operation.

A method for operating a power tool, wherein the power tool is initially operated with a first combination of operating parameters such that a first working progress is obtained. During operation of the power tool with the first combination of operating parameters, the first working progress can be determined and compared with a second working progress that is obtained when the power tool is operated with a second combination of operating parameters. Depending on the result of the comparison, the power tool can continue to be operated with the second combination of operating parameters or the power tool can return to operation with the first combination of operating parameters. This comparison of the working progresses can be repeated until a maximum, i.e. optimal working progress is reached or found. A power tool, wherein the power tool is preferably in the form of a drill, preferably a core drill.