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Information on Drawings

1-1. Information on Drawings

Drawings contain different lines, scales, and symbols. To read drawings, you must be able to interpret these items. They also include other information in the form of schedules, notes, and tables.

a. Schedule of Drawings. A schedule of drawings lists the drawings by number, title, and sheet number (Table 1-1). It is usually on the first drawing of a set of prints.

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Table 1-1. Schedule of drawings

b. General Notes. General notes give additional information that is needed (Figure 1-1). For example, item number 3 is for the carpenter.

Figure 1-1. General notes
Figure 1-1. General notes

c. Graphic and Ratio Scales. Because of the sizes of the objects being represented, different scales are used for drawings (Figure 1-2).

Figure 1-2. Graphic and ration scales
Figure 1-2. Graphic and ration scales

d. Lines on Drawings (Figure 1-3). Line conventions most often seen on working drawings are-

(1) Visible Lines. A heavyweight unbroken line is used for the primary feature of a drawing. For drawings of objects, this line convention represents the edges, the intersection of two surfaces, or the surface limit that is visible from the viewing angle of the drawing. This lines is often called the outline.

(2) Hidden Lines. A medium weight line of evenly spaced short dashes represents an edge, the intersection of two surfaces, or the surface limit which is not visible from the viewing angle of the drawing.

(3) Center Lines. A thin (light) line composed of alternate long and short dashes of consistent length is called a centerline. It is used to signify the center of a circle or arc and to divide object into equal or symmetrical parts.

(4) Dimension Lines. A solid, continuous line terminating in arrowheads at each end. Dimension lines are broken only to permit writing in dimension. On construction drawings, the dimension lines are unbroken. The points of the arrowheads touch the extension lines which mark the limits of the dimension. The dimension is expressed in feet and inches on architectural drawings and in feet and decimal fractions of a foot on engineering drawings.

(5) Extension lines. An extension line is a thin (light), unbroken line that indicates the extent of the dimension lines. The extension line extends the visible lines of an object when it is not convenient to draw a dimension line directly between the visible lines. There is always a small space between the extension line and the visible line.

Figure 1-3. Line conventions
Figure 1-3. Line conventions

e. Architectural Symbols. These symbols are used on drawings to show the type and location of doors, windows, and material conventions. To understand construction drawings, you must be able to recognize and interpret these symbols (Figure 1-4).

Figure 1-4. Architectural symbols
Figure 1-4. Architectural symbols

Figure 1-4. Architectural symbols (continued)
Figure 1-4. Architectural symbols (continued)

 
Curriculum design: David L. Heiserman
Publisher: SweetHaven Publishing Services

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