A method of machining at least one dental restoration (1) from a workpiece (2) using one or more dental took (3), including a step of defining, a target contour (4) of the dental restoration (1); also including a step of predicting the deflection of the dental tool (3) during pre-machining through a model based on one or more machining parameters; a step of determining based on the prediction step one or more primary locations (5) at which the target contour (4) would have been damaged during pre-machining; a step of modifying the target contour (4) or the corresponding machining path by adding an oversize of material (6) substantially only at the primary locations (5) for preventing damage; and a step of pre-machining the workpiece (2) based on the modified target contour (17) or the corresponding modified machining path.

A numerical control device according to one aspect of the present disclosure capable of easily setting a tip point control is provided with: an edge shape information storage unit; a center position calculation unit that calculates a center position of rotation of a multi-edge tool having machining edges; an edge switching determination unit that determines whether or not edge switching is to be performed; a calculation method changing unit that takes the edge shape information into account and changes, in association with the edge switching, a method for calculating the center position by the center position calculation unit; a tip position back calculation unit that, on the basis of the calculation method changed by the calculation method changing unit, back-calculates a tip position after the edge switching from the center position immediately before the edge switching; and a change amount calculation unit that calculates, on the basis of a tip position and a shaft angle before the edge switching and the tip position and a shaft angle after the edge switching that have been calculated by the tip position back calculation unit, a required change amount of the center position, and calculates a driving amount of a driving shaft for moving a tool rotation axis by the calculated change amount.

A numerical control device according to one aspect of the present disclosure capable of easily setting a tip point control is provided with: an edge shape information storage unit; a center position calculation unit that calculates a center position of rotation of a multi-edge tool having machining edges; an edge switching determination unit that determines whether or not edge switching is to be performed; a calculation method changing unit that takes the edge shape information into account and changes, in association with the edge switching, a method for calculating the center position by the center position calculation unit; a tip position back calculation unit that, on the basis of the calculation method changed by the calculation method changing unit, back-calculates a tip position after the edge switching from the center position immediately before the edge switching; and a change amount calculation unit that calculates, on the basis of a tip position and a shaft angle before the edge switching and the tip position and a shaft angle after the edge switching that have been calculated by the tip position back calculation unit, a required change amount of the center position, and calculates a driving amount of a driving shaft for moving a tool rotation axis by the calculated change amount.