PRIN. OF DRAFTING AND SHOP DRAWINGS - OD1641 - LESSON 1/TASK 3
characteristics of the front view by positioning the object with as many holes as
possible located in the front view.
Figure 62 shows two oblique drawings of the
same object and demonstrates the value of correct positioning. In the drawing on
the left, the object is positioned so that all holes are located in the front view;
in the drawing on the right, the object is positioned so that the holes are located
in one of the receding surfaces. This difference of positioning enables the left
drawing to be drawn by using circles for holes; the right drawing requires
elliptical holes. Because of the elliptical hole requirement, the drawing on the
right takes about four times as long to draw as the drawing on the left.
In
addition, there is no appreciable gain in technical clarity:
It is, however,
important to remember that in positioning an object, your first consideration
should be technical clarity and ease of understanding for the reader and not ease
of drawing for the draftsman.
FIGURE 62.
TWO OBLIQUE DRAWINGS OF THE
SAME OBJECT, ONE CORRECTLY
POSITIONED AND ONE POORLY
POSITIONED.
d. Rounded and Irregular Surfaces. Figure 63 (on the following page) is a sample
problem that involves creating an oblique drawing from given orthographic views
that contain a rounded surface.
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