measuring distances along normal lines on themulti-view projection and laying them off alongthe corresponding isometric lines on the isometricdrawing. The angle that measures 40 degrees onthe top multi-view view measures only about32 degrees on the isometric drawing. Note,however, that it is labeled 40 degrees on theisometric drawing. This is because it actually isa 40-degree angle as it would look on a surfaceplane at the isometric angle of inclination.Circles in Isometric.— A circle in a normal multi-view view will appear as an ellipse in an isometricdrawing. This is shown in figure 5-42, view A.A procedure that maybe used to construct anisometric circle is shown in figure 5-42, view B.The steps of that procedure are as follows:1. Draw the isometric center lines of thecircle. Then, using those center lines, lay off anisometric square with sides equal to the diameterof the circle.2. From the near corners of the box, drawbisectors to the opposite intersections of the centerlines and the box. The bisectors will intersect atfour points (A, A´, B, B´), which will be thecenters of four circular arcs.3. Draw two large arcs with radius R, usingPoints A and A´ as centers, Draw the two smallerarcs with radius r, using Points B and B´ as centers.If the above discussion seems familiar, itshould. It is simply an approximation of the four-point method you studied in the previous chapter.However, it can be used only when drawingisometric circles on an isometric drawing.Noncircular Curves in Isometric.— A line thatappears as a noncircular curve in a normal multi-view view of an object appears as a non-isometricFigure 5-43.-Method of drawing a noncircular curve inisometric.line in an isometric drawing. To transfer such aline to an isometric drawing, you must plot aseries of points by measuring along normal linesin the multi-view view and transferring thesemeasurements to corresponding isometric lines inthe isometric drawing.The upperpart of figure 5-43 shows a two-view multi-view projection of a block withFigure 5-42.-A circle on a normal multi-view view appears as an ellipse in an isometric drawing.5-23
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