Instead of rotating the whole pyramid, simply rotate

the line of the edge itself into the horizontal on a

conventional orthographic view. For example, in view

C, the line of an edge from apex to base, as it appears

in the top view, is used as the radius for an arc to the

horizontal The point of intersection of the arc with the

horizontal is projected to the front view. A true-length

line for that edge is drawn (view D).

The following steps for developing a truncated

pyramid are shown in figure 14-50. This is a transition

piece for connecting a large square pipe with a smaller

one. Normally, the square ends would end in square

collars, which also would be developed.

1. Draw the orthographic views, completing the

lines of the sides to the apex (view A).

2. Rotate the line of one edge in the top view to the

horizontal and project it to the front view (view

W

3. Draw an arc with a radius equal to the length of

this true-length line, plus its extension to the

apex of the pyramid. Draw a second arc

defining the upper limit of the true-length line

To develop a truncated pentagonal pyramid, like

(view C).

that shown in figure 14-51, follow the same general

4. Step off lengths along these arcs equal to the

steps. However, since one lateral edge appears in its

sides of the pyramid (view D).

true length in the front view, the limits of the other edges

can be projected onto the line of this edge to determine

5. Connect these points with the vertex, as shown

the true lengths. Measure the length of each edge.

in view D.

Transfer this measurement to the development.

Figure 14-52 shows the following steps in the

development of an offset transition piece. It is offset

14-32