Bezugachse

Bezugachse, literally “reference axis,” is a term used in engineering, manufacturing and technical drawing to denote a fixed axis that serves as a reference frame for measurements, orientations and tolerances. It functions as a baseline against which deviations, rotations and positions are defined. In drawings and CAD models, the Bezugachse may coincide with the part’s central axis, such as the longitudinal axis of a cylindrical component, or with a designated datum axis chosen to stabilize the coordinate system.

In practice, several Bezugachsen can be defined in a single assembly: a primary Bezugachse establishes the main alignment, while secondary or tertiary Bezugachsen are used for additional features or tolerancing. Measurements like runout, angular position, or radial deviation are often specified relative to these axes.

Applications include machining and quality control, where tools, fixtures and gages refer to the Bezugachse; robotics and kinematics, where joint movements are expressed with respect to a reference axis; and CAD/CAE, where a datum axis guides operations such as lofts, sweeps or symmetry analyses.

Relation to datums: the Bezugachse is closely related to the concept of a datum axis; when a datum is defined in a standard, its axis provides the fixed frame for all subsequent tolerances and inspections. Etymology: from German Bezug ('reference') and Achse ('axis'). In English technical usage the term is usually translated as “reference axis” or “datum axis.”