3.2: The Meaning of Lines
Remember to read blueprints and create effective drawings; you must understand the use of lines. The alphabet of lines is the common language of the technician and the engineer. In drawing an object, the different views are arranged in a certain way, and various lines convey the information. Here is another example of the use of standard lines in a simple drawing is shown in Figure \(\PageIndex{1}\). Line characteristics, such as width, breaks in the line, and zigzags, are shown below in Figure \(\PageIndex{2}\).
Line Standards
Table \(\PageIndex{1}\): Line characteristics and conventions for drawings.
| Name | Convention | Description and Application | Example |
| Center Lines |
Thin lines made up of long and short dashes alternatively spaces and consistent in length. Used to indicate symmetry about an axis and location of centers. |
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| Visible Lines |
Heavy unbroken lines. Used to indicate visible edges of an object. |
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| Hidden Lines |
Medium lines with short evenly spaced dashes. Used to indicate concealed edges. |
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| Extension Lines |
Thin unbroken lines. Used to indicate extent of dimensions. |
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| Dimension Lines |
Thin lines terminated with arrow heads at each end. Used to indicate distance measured. |
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| Leader |
Thin line terminated with arrowhead or dot at one end. Used to indicate a part, dimension or other reference. |
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| Break (Long) |
Thin, solid ruled lines with freehand zigzags. Used to reduce size of drawing required to delineate object and reduce detail. |
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| Break (Short) |
Thick, solid free hand lines. Used to indicate a short break. |
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| Phantom or Datum Line |
Medium series of one long dash and two short dashes evenly spaced ending with long dash. Used to indicate alternate position of parts, repeated detail or to indicate a datum plane. |
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| Stitch Line |
Medium line of short dashes evenly spaced and labeled. Used to indicate stitching or sewing. |
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| Cutting or Viewing Plan - Viewing Plane Optional | Thick solid lines with arrowhead to indicate direction in which section or plane is viewed or taken. | ||
| Cutting Plane for Complex or Offset Views |
Thick short dashed. Used to show offset with arrowheads to show direction viewed. |