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THIRD-ANGLE PROJECTION | Up
Engineering Aid 3 - Beginning Structural engineering guide book | Next
Use of a miter line |
Figure 5-8.-A third-angle projection brought into a single plane.
Again you assume that the vertical plane is
already in the plane of your drawing paper. To
get the other two views into the same plane, you
rotate them both clockwise.
Figure 5-8 shows a third-angle projection
of an object brought into a single plane.
The top view is above the front view; the
Figure 5-9.-Method of making a third-angle projection.
right side of the object, as shown in the
front view, is toward the right side view;
and the top, as shown in the front view, is toward
the top view.
Figure 5-9 shows the basic principles of
the method by which you would actually
make the projection shown in figure 5-8.
Draw a horizontal line AB and a vertical
line CD, intersecting at O. AB represents
the joint between the horizontal and the
vertical plane; CD represents the joint between
these two and the profile plane. Any one
of the three views could be drawn first,
and the other two projected from it. Assume
that the front view is drawn first on the
basis of given dimensions of the front face.
Draw the front view, and project it upward
with vertical projection lines to draw the
top view. Project the top view to CD with
horizontal projection lines. With O as a
center, use a compass to extend these pro-
jection lines to AB. Draw the right side
view by extending the projection lines from
AB vertically downward and by projecting
the right side of the front view horizontally
to the right.
5-5
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