A-A-52300 Protractors, Circular And Semicircular, (Mils, Degrees)This description covers circular protractors of plastic and semicircular protractors of brass or plastic for use in graphically measuring precise angles required by mapping and precision drafting techniques.

Pages 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9

A-A-52300

Type II – Circular, graduated in degrees.

Style 1 – Zero to 360 degrees.

Style 2 – Zero to 90 degrees quadrants and zero to 360 degrees.

Sizes (diameter)

6 inches

8 inches

10 inches

Type I semicircular. Type I protractors shall be of brass of plastic. Numbers may be slanted in the direction of increase. The outer row of numbers on the graduated arc shall read clockwise or counterclockwise and the inner row of numbers shall read in the opposite direction.

Class A. The outer edge of the arc shall be graduated in degrees so that the zero and 180 degree marks are on the horizontal axis of the protractor. When the upper edge of the crossbar forms the horizontal axis, the graduations may be extended below that axis. The graduation marks that extend below the zero and 180 degrees marks of the horizontal axis are the arc extension.

Class B. The outer edge of the arc shall be graduated in mils so that the zero and 3200-mil marks are on the horizontal axis of the protractor. When the upper edge of the crossbar forms the horizontal axis, the graduations may be extended below that axis.

NOTE: A mil is defined as 1/6400 of a circle. The graduation marks for protractors reading mils shall be not less than three lengths; the shortest length denoting 10-mils, the medium length denoting each 50-mil increment, and the longest denoting each 100-mil increment. Graduation marks shall be numbered every 100-mils in two rows of figures.

Style 1. Configuration of style 1 protractors shall be similar to that shown on figure 1.

Style 2. Configuration of style 2 protractors shall be similar to that shown on figure 2.

Type II, circular. Type II protractors shall be of plastic. Numbers may be slanted in the direction of increase.

Style 1. The outer row of figures shall read either clockwise or counterclockwise from zero to 360 degrees, starting at the horizontal axis. The inner row of figures shall read in the direction opposite that of the outer row, starting on the opposite end of the horizontal axis. Configuration of type II, style 1 protractors shall be similar to figure 3.