Figure 14-44.--Development for a four-piece elbow.
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
6. Using a T-square, project the lengths of the
elements on the front view to the development
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
Figure 14-45.--Development of a T-joint with two cylindrical
intersections are determined by carefully drawing the