| 摘要 |
FIELD: mechanization of graphic drawing works. SUBSTANCE: drawing instrument has drawing board, T-square fixed on working surface of drawing board, mechanism for planar-parallel displacement of T-square positioned adjacent to rear side of drawing board and formed as four-member pivotal parallelogram, whose one member of opposite members is connected with T-square and other member formed as flat ring is positioned on drawing board. Parallelogram is mounted for rotation through 360 deg in its own plane about center of drawing board, which is connected with support through flat ring. Drawing board is made circular, with goniometric scale applied adjacent to circle edge. Flat ring is mounted on drawing board through circular guide and is provided with control handle having scale indicator and retainer. T-square made from transparent material has longitudinal slot with working facets and notch lines made on rear side and extending in parallel with working facets. Space between facets and notch lines corresponds to pin size. EFFECT: increased efficiency and precision, improved convenience, reduced sizes of drawing board. |
