Copyright Goodheart-Willcox Co., Inc. Unit 2 Line Conventions and Lettering 19 are characterized by a set of views. Within each view, many features may be hidden, while other features may be curved or symmetrical. Of utmost importance is the visible line. This is a thick, continuous line representing all of the edges and surfaces of an object that are visible in the view, Figure 2‑3. These lines should be twice as thick as the thin lines of the view. Visible lines give the print reader the shape description of the object. Many books and drafting teachers have also referred to visible lines as object lines. Another line that is especially important in the multiview drawing is the hidden line. This is a line that features thin, short dashes spaced closely together. Earlier standards recommended the dashes be about 1/8″ long and spaced approximately 1/32″ apart. Hidden lines are used to show edges, surfaces, and features not visible in a particular view, Figure 2‑3. Hidden lines are used to clarify a draw- ing. Sometimes, hidden lines are omitted on complex views when the drawing is clear without them. On older drawings, these lines may have been cre- ated with a medium weight. In summary, the hidden line should be comprised of thin, black, short dashes spaced closely together. A drafter will also start the hidden line with a gap if it might otherwise give the appearance that a visible line continues. The third type of line especially important in the multiview drawing is the center line. This is a thin line with alternating long and short dashes used to designate centers of holes, arcs, and other symmetri- cal features, Figure 2‑4. In a circular view, two center lines are used and should form a “plus” in the center of the circle. Some CAD programs do not, by default, Goodheart-Willcox Publisher Figure 2‑2. This drawing features visible lines, hidden lines, center lines, phantom lines, section lines, a cutting-plane line, a viewing-plane line, dimension lines, extension lines, leader lines, and a chain line. Can you find all of them?