the illustration shown in figure 12-38. Then break out

your layout tools and a sheet of template paper and try

your skills at drawing an intersected pipe layout.

First, construct a base line. After the base line, draw

your miter line at the same degree of angle as that of the

slanting roof or inclined plane, as shown in figure

12-38. The elevation is the front view. Line AB

represents the diameter of the pipe. The distance

between line AB and the miter line is the height of the

pipe, which will vary around the circumference of the

pipe.

Now determine the center of line AB, and construct

a center line as shown in figure 12-38. Set your dividers

for one-half the distance of line AB. Develop the plan

by the following steps:

1. Construct line 1-7 parallel to and just above AB.

Using the point at which the center line of the elevation

intersects line 1-7, swing an arc with the dividers and

complete the half-plan as shown.

2. Step off the circumference of the half-plan with

the dividers into six equal parts. To do this, place one

leg of your dividers at point 1. With the same

measurement used to scribe the half-plan, scribe a mark

on the arc at point 3. Then from point 3 scribe a mark

at point 5. You now have three equal parts. Bisect these

three sections as an arc and you end up with your

required six equal parts.

3. Set your straightedge at right angles to the center

stretchout for the elevation. You may use either of two

line. With the straightedge as a base line, use the flat

methods:

steel square to draw lines parallel to the center line by

the method shown earlier in figure 12-3. The parallel

Measure and transfer the measurement from the

lines must be drawn from the points where the arcs

elevation to the stretchout with your dividers.

intersect the circumference of the half-plan to the miter

Project the points in the elevation to the

line (fig. 12-39).

stretchout by parallel projection lines (broken

4. with the straightedge draw EF (an extension of

lines).

line AB), and step off twice the distance you stepped off

Whichever method you use, the stretchout will be

in the circumference of the half-plan.

the same. However, your measurements must be

5. Draw line GH the same length as EF parallel to

accurate. Try both methods and make a habit of using

EF so that lines drawn from G to E and from H to F will

the one that comes easiest to you.

both be perpendicular. The distance between line EF

To develop your pattern by the use of dividers,

and line GH will be equal to the greatest height of the

follow these step-by step instructions, working from

elevation.

figure 12-39.

6. Through the points located on the extended line,

1. Take your dividers and set them to the distance

by stepping off with the dividers, draw parallel lines at

of line 1 where it intersects line AB to its intersection

right angles to the line extended from AB.

on line CD.

7. Number these lines in the proper order as shown

2. Transfer this measurement to the two lines

(from 1 to 7 and back to 1).

numbered 1 in the stretchout. Use line EF as your base

line for the measurements on the strecthout, and scribe

You are now ready to transfer the miter line CD in

an arc on line 1.

the elevation to the stretchout and thus form the

12-14