Graduated rule for drawing - has graduated scale protected by a transparent material strip

摘要

A graduated rule used for engineering drawing has the graduated scale protected. The rule has a flat straight strip (1) of transparent material. It also has a slot (2) into which is fitted a graduated scale (3). Part of the scale (2) is protected by the material of the flat strip (1). Graduation and numerals of the scale (2) can only be read through the protective part of the strip (1). The slot (2) is perpendicular to the edge of the strip (1). The depth of the slot (2) may be equal to the width of the scale (3). The slot (2) may also be slanted to the edge of the strip (1) and only one side of the scale (3) may be protected.