PRIN. OF DRAFTING AND SHOP DRAWINGS - OD1641 - LESSON 1/TASK 3
To determine exactly if and how much of the bottom edge of the hole should be
drawn, locate the center point of the hole on the bottom surface and draw the hole
by using the same procedure you used for the hole on the top surface. If the hole
drawn on the bottom surface appears within the hole on the top surface, it should
appear on the finished drawing. If the hole drawn on the bottom surface does not
appear within the hole on the top surface, it should not appear on the finished
drawing.
Figure 49 (on the previous page) presents a sample problem that
illustrates this procedure.
d. Round and Irregular Surfaces.
Figure 50 is a sample that requires you to
create an isometric drawing from given orthographic views that contain a round
surface. To make an isometric drawing of a round surface, use either an isometric
template for a guide or the point method.
FIGURE 50.
ISOMETRIC DRAWING PROBLEM
WITH A ROUNDED SURFACE.
Figure 51 (on the following page) is the solution that was derived by using an
isometric template.
(1) To draw a round surface by using an isometric ellipse template, perform the
following steps:
Step 1.
Define on one of the orthographic views (the one that shows the round
surface as part of a circle) the center point of the round surface and the
intersections of the center lines with the surfaces of the object. In this example
the center
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