ALPHABET OF LINES
OBJECTIVES
•Interpret plans, diagrams, and working drawings.
•Apply appropriate technical and graphic communication in the
technological systems.
•Identify Line Types for the Alphabet of Lines
•Construct lines properly on drawings.
•Hierarchy of lines
ALPHABET OF LINES
• The lines used in drafting are referred to as the Alphabet of lines.
• Lines are classified by line thickness and drawn thin or thick.
• Line types and conventions for mechanical drawings are
covered in ANSI Standard Y14.2M.
Lines are made in definite standard forms: (all have specific
meaning) Thickness of a line (thick or thin)
•Thick lines are typically drawn with a 0.7 mm or 0.9 mm
mechanical pencil.
•Thin lines are typically drawn with a 0.3 mm or 0.5 mm
mechanical pencil.
Solid
Broken
Dashed
LINE USED IN ARCHITECTURAL DRAWING
ALPHABET OF LINES
PROPERTY LINES
BORDER LINES
OBJECT LINES
CUTTING OR PLANE LINES
SHORT OR BREAK LINES
HIDDEN LINES
CENTER LINES
SECTION LINES
ALPHABET OF LINES
EXTENSION LINES 2.0 M
DIMENSION LINES
LONG BREAK LINES
GUIDELINES
CONSTRUCTION LINES
LEADERS
LINE TYPE APPLICATION
Visible lines / Object Lines:
Visible lines (object lines) are continuous lines
used to represent the visible edges and contours
(features) of an object.
Since visible lines are the most important lines,
they must stand out from all other secondary lines on the
drawing.
VISIBLE LINES
Hidden Lines:
Hidden lines are short-narrow dashed lines. They
represent the hidden features of an object.
Hidden lines should always begin and end with a dash,
except when a dash would form a continuation of a
visible line.
HIDDEN LINES
VISIBLE LINES
Dimension Lines:
Dimension lines are used to show the extent and the direction of dimensions. If
possible, dimension lines are aligned and grouped for uniform appearance.
All dimension lines terminate with an arrowhead on mechanical engineering
drawings; a slash, or a dot in architecture.
The preferred ending is the arrowhead.
Note: In Solid Works, inserted dimensions in the drawing are displayed in gray.
Imported dimensions from the part are displayed in black.
VISIBLE LINES
HIDDEN LINES
DIMENSION LINES
Extension Lines:
Extension lines are used to indicate the termination of a dimension.
An extension line must not touch the feature from which it extends, but should
start approximately (2 - 3 mm) from the feature being dimensioned and
extended the same amount beyond the arrow side of the last dimension line.
When extension lines cross other extension lines, dimension lines, leader lines, or
object lines, they are usually not broken. When extension lines cross dimension
lines close to an arrowhead, breaking the extension line is recommended for
clarity. black.
VISIBLE LINES EXTENSION LINES
DIMENSION LINES
EXTENSION LINES
A leader line is a continuous straight line that extends at an angle from a note, a
dimension, or other reference to a feature.
An arrowhead touches the feature at that end of the leader.
At the note end, a horizontal bar (6 mm) long terminates the leader
approximately (3 mm) away from mid- height of the note's lettering, either at the
beginning or end of the first line.par
Leaders should not be bent to underline the note or dimension. Unless
unavoidable, leaders should not be bent in any way except to form the
horizontal terminating bar at the note end of the leader.bl
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Leaders usually do not cross.
Leaders or extension lines may cross an outline of a part or extension lines if
necessary, but they usually remain continuous and unbroken at the point of
intersection. When a leader is directed to a circle or a circular arc, its direction
should be radial. LEADER LINES
ck.
Break Lines:
Break lines are applied to represent an imaginary cut in an object, so the interior
of the object can be viewed or fitted to the sheet. Line weight is thick (0.5 – 0.6
mm) the part are displayed in black.
BREAK LINES
Center Lines:
Center lines are thin, long and short dashes, alternately and evenly spaced, with
long dashes placed at each end of the line.
Center lines are used to represent the axes of symmetrical parts of features, bolt
circles, paths of motion, and pitch circles.
Every circle, and some arcs, should have two centerlines that intersect at their
center of the short dashes.
VISIBLE LINES
CENTER LINES
CENTER LINES
Cutting Plane Lines:
Cutting Plane lines show where an imaginary cut has been made through an
object in order to view and understand the interior features.
Line type is phantom.
Arrows are located at the ends of the cutting plane line and the direction
indicates the line of sight into the object.
SECTION LINES
CUTTING PLANE
LINES
Section Lines:
Section lines are thin, uniformly spaced lines that indicate the exposed cut
surfaces of an object in a sectional view. Spacing should be approximately (3
mm) and at an angle of 45°. The section pattern is determined by the material
being "cut" or sectioned. Section lines are commonly referred to as "cross-
hatching."
SECTION LINES
Section Lines:
The section pattern is determined by the material being "cut" or sectioned.
Section lines are commonly referred to as "cross-hatching."
