5. Set your dividers equal to the distance of the

step-offs on the half-plan, and step off twice as many

spaces on the stretchout as you have in the half-plan.

6. Number the step-offs from 1 to 7 and back to 1,

and draw connecting lines from vertex A to the number

1 at each end of the stretchout.

7. With vertex A as the center, set your dividers

along line AC the distance of line AD, and scribe an arc

that intersects both lines drawn from A to 1.

The area enclosed between the large and small arcs

and the number 1 lines is the pattern for the frustum of

a cone. Add allowances for seaming and edging and the

stretchout is complete.

To develop a pattern for a cone cut at any angle, you

need merely to elaborate the development of the pattern

for a frustum. Such a pattern is shown in figure 12-50.

To develop a pattern for a cone cut at any angle,

follow the method given here step by step:

1. Draw a cone with line ED cutting the cone at

the required angle, as shown in figure 12-50.

a cone is that part that remains after that point, or top,

has been removed.

To develop a pattern for the frustum of a cone, check

the following steps one-by-one with the illustration

shown in figure 12-49.

1. Draw a front view of a cone, using such

dimensions as your job at hand requires. Letter the

vertex A, the base BC, and the axis AO.

2. At point D, and parallel to line BC, draw a line

that cuts the top from the bottom of the cone. The

bottom portion is called the frustum.

3. Draw a half-plan (using center 0 and radius OB)

beneath the base of the frustum. Step the half-plan off

into an equal number of spaces, and number them as

shown in the illustration.

4. Set your dividers the distance of line AC, and

using the vertex A as a center, scribe an arc of indefinite

length.

12-19

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