elements intersecting on orthographic views and then

3. Lay off the base line, called the stretch-out line,

projecting or transferring these intersection points to the

of the development. The length of this line can

be calculated as š times the diameter of the

developments. The following steps in making

cylinder (3.14 × D).

developments for a T-joint are shown in figure 14-45.

4. Divide the stretch-out line into twice the number

of equal parts as the number on the half circle of

the orthographic view (view C).

5. Erect perpendiculars at each point, as shown in

view C.

6. Using a T-square, project the lengths of the

elements on the front view to the development

(view D).

7. Using a French curve, join the resulting points

of intersection in a smooth curve.

When the two pieces of the elbow are the same, you

only need to make one drawing.

When a four-piece elbow is to be drawn, follow the

same steps to produce as many developments as may be

required. The orthographic view may be drawn of the

whole elbow and the developments drawn beside each

separate piece, as shown in figure 14-44. Here, only

one end and one middle development are drawn. The

other two pieces are the same as these.

You must determine the exact points of intersection

when two pieces, such as two cylinders or a cylinder

and a prism, intersect. This is so you can make

developments, for the pieces, that will fit together

without gaps or unnecessary overlaps. These

intersections are determined by carefully drawing the

14-28