| 摘要 |
PURPOSE: To increase an accuracy in the case of equally dividing circles and an integrity of a drafting method by installing surveying and figure drawing instruments at relative positions obtained by a specific relation formula to form one row of chord gage scale, and performing many relative functions of equally dividing circle, polygonal shape drafting, angular distribution on a circumference or the like by the surveying, figure drawing instruments. CONSTITUTION: First, result values of a CAD relation formula C=D×sin (180 deg./N) are arranged, and a CAD table (I) is formed, wherein D= a diameter of an equally divided circles, N = equal fraction and C = equal chord length. For example, when taking an equal relative chord length of a circumference 7 in the table, its formula is C=0.43390. Thus, a line K of an arbitrary direction is drawn on a flat surface, further three points of l, m, n are taken on the line, and a ratio of m:n is set to 0.4339. Three straight lines parallel to each other are formed as L, M and N lines in different arbitrary directions passing the three points of the l, m and n. In this case, the lines become one set of convenient circumference 7 equally dividing drafting tool line. Its function has extremely large elastic force, is applied to a circumference of arbitrary size diameter, and the drafting is fast and accurate, and time needs during equally dividing is not eliminated.
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