Abstract: Aimed to the problem that the shapes of the calibrator are complex and irregular, there are
many internal holes, the workload of the dimensioning and layouts are large, the structural
characteristics of the model are analyzed, and based on the three-dimensional software UG NX
(Unigraphics NX) platform, the automatic dimensioning system for the engineering drawing of the
calibrators is developed. The requirements of the dimension are summarized, and the engineering
drawing templates are created. Through feature extraction, the redundant edges of automatic
engineering drawings of three-dimensional models are deleted automatically. Based on the extracted
mark datum, the vacuum holes, water holes, locating key are dimensioned, and according to the
positions, the dimensions are laid out reasonably. A case study presented to verify the practicability of
the engineering drawing automatic dimensioning system. The research simplifies the design process and
improves the design efficiency.

Key words: engineering drawing, automatic dimensioning, calibrator, UG secondary development