Line Interpretation and Basic Views

hidden line

A dashed line that represents an edge that cannot be seen in the current view

multiview drawing

A drawing that contains multiple views of an object; these are orthographic drawings and present the object in two or more views. See orthographic drawing

object line

A heavy, solid line used to define the shape and size of a part or feature

center line

A line that defines the center (axis of symmetry) of a symmetrical part or feature; it is made using alternating long and short dashes. Often used to locate the center of circles or arcs or show the symmetrical alignment of a pattern of features

extension line

A line that extends perpendicular from the dimension line to the part drawing, relating the dimension line to the appropriate part feature

dimension line

A line that indicates the measurements of the object. It is drawn as a straight line with an arrowhead at each end and the measurement, or dimension, in the center

break line

A line used to indicate that a section of a part has been left out of the drawing. There are two types of these lines, short and long

isometric views

A type of drawing that depicts 3D objects in two dimensions in such a way that equal dimensions will measure the same along each of the three coordinate axes (that is, there is no foreshortening). The x- and y- axes are each 30° from the horizontal; the z-axis is vertical

orthographic drawing

An illustration that represents a three-dimensional object through the use of multiple two-dimensional drawings (such as front, side and top views)

section lines

Closely spaced diagonal lines indicating the surface of the material that the cutting plane cuts

chain line

Heavy, alternating long and short dashes that indicate a surface area requiring additional treatment

phantom lines

Thin lines, drawn as a long dash alternating with two short dashes, used to indicate things not seen in the current view (e.g., adjacent parts, alternate positions for moving parts, etc.)

leader line

Used to connect a note, a radial dimension or a dimension that will not fit in a detail area with the appropriate part of the drawing. It typically runs at an angle from the note to the drawing, with a horizontal portion at the note end of the line and an arrowhead at the other end pointing to the feature being described

cutting plane line

When a sectional view is shown to illustrate the interior of a part, this line shows where the imaginary cut is made to produce that view. Consists of two short dashes alternating with a long dash; it has arrowheads at both ends, perpendicular to the line and pointing toward the portion of the part that will be seen in the cutaway view