82 Print Reading for Industry Copyright Goodheart-Willcox Co., Inc. Fillets, Rounds, and Runouts Molded and cast objects have rounded edges called fillets and rounds, Figure 5-16. Fillets are interior rounded edges. Rounds are exterior rounded edges. Most CAD programs have a com- mand called FILLET to perform this task of rounding corners, both interior and exterior. These rounded corners also create situations where the drafter has to decide whether or not to project the edge. Conventional practice calls for the lines to be shown if needed for clarity in describing the object. This is sometimes a judgment call. If the edge is shown, the line can be projected as if the corner is sharp or square. When a rounded corner intersects a curved surface, the edge fades, or “tails” out. This is called a runout, Figure 5-16. However, this is different than runout as defined in Unit 13, Geometric Dimensioning and Tolerancing. Meanings of a Multiview Line There are three meanings a line in a multiview drawing can have. A multiview line can represent an edge view, an intersection, or a maximum contour element of a curved surface. See Figure 5-17. These meanings apply whether the line is visible or hidden. There are many different perimeter shapes that a flat surface can have, such as circular, square, or polygonal. Yet, if the surface is perpendicular to the projection plane, it simply projects as a line, or what may be called an “edge view.” Therefore, many lines in a multiview drawing represent the edge view of planar surfaces. Curved surfaces also are seen as “circular” edge views if the curved sur- face is perpendicular to the projection plane. Refer to Figure 5-17. Goodheart-Willcox Publisher Figure 5-15. This figure helps illustrate how cylindrical surfaces are projected in multiview drawings. Goodheart-Willcox Publisher Figure 5-16. Fillets are interior rounded edges. Rounds are exterior rounded edges. When rounded edges intersect curved surfaces, a runout is used to show how the edge tails out. Runout Round Fillet