Unit 4 Lines and Symbols Flashcards
Alphabet of Lines
The accepted drafting practice of using specific line thickness and style to represent various drawing features.
arrowheads
Marking devices placed at the ends of a dimension line to define the distance between points (extension lines) on the drawing.
border lines
Lines located near the edge of the sheet of drawing paper, serving as the drawing border.
break lines
Lines used to indicate that only a portion of an object is shown.
centerlines
Thin lines composed of alternating long and short dashes, used to indicate centers of objects.
dimension lines
Thin lines used to indicate dimensions, extending the length of a distance being measured.
extension lines
Thin lines used in dimensioning, drawn perpendicular to the dimension line to specify the features between which the dimension applies.
hidden lines
Lines composed of a series of short dashes evenly spaced and consistent in length, used to define edges and surfaces that are not visible in a particular view.
leader
A thin line that has an arrow at one end and a text note or symbol at the other end. The arrow points to the feature or detail to which the note refers.
object lines
Lines that represent the main outline of the features of the object. Object lines are heavy, continuous lines showing all edges and surfaces.
section cutting lines
Lines identifying sectional views. A section cutting line marks the part of the drawing being “cut” to create a sectional view. Arrows on the end of a section cutting line indicate the direction from which the section is being viewed.
section lines
Thin lines, usually drawn at a 45c angle, used in a sectional view to represent a building material.
