ALPHABET OF LINES Extension lines are also thin lines, showing the limits
of dimensions.
The Alphabet of Lines in Technical Drawing 4.
Lines in technical drawings are part of a
specialized graphic language that is standardized
throughout industry. Each type of line has a very HIDDEN LINE- Short dash lines use to show non
precise symbolic meaning. Correct usage of this visible surfaces. Usually shows as medium thickness.
"alphabet of lines" is essential whether you use Hidden lines are dashed and thin, and they show the
traditional drafting methods. The "Alphabet of Lines" edges that are not visible from the view, but are still
refers to the different styles of lines used in drafting to part of the object.
show different features about an object that is drawn.
There are eleven main line types - visible, hidden, 5.
center, dimension, extension, leader, section, cutting-
plane, phantom, viewing plane and break. Each line CENTER LINE- Long and short dash lines. Usually
has a definite form and line weight. indicates center of holes, circles and arcs. Line is thin
The technical drawing is a form of design and dark.
communication based on line symbols recognized
and understood worldwide. Hence, technical
drawing is often referred to as a universal language
understood (readable) by anyone regardless of the
language they speak.
Line weight is the thickness of the line. 6.
Construction lines and guide lines are very light,
easily erased lines used to block in the main layout.
Visible lines are the edges or "outlines" of an object. EXTENSION LINE- Thin and dark line use to show the
They are drawn as solid lines with a thick/heavy starting and ending of dimension. Extension
weight. lines continue or extend from the surface of the
All other lines contrast with the visible lines object and establish the size of the dimension. They
by having either a thinner weight and/or a do not touch the object lines and extend slightly past
combination of dashes. the dimension line. Extension lines provide a means
of displaying a measurement.
1. OBJECT OR VISIBLE LINES- Thick dark line use to
show outline of object, visible edges and surfaces.
Object lines stand out on the drawing and clearly
define the outline and features of the object.
2.
CONSTRUCTION LINE- Very light and thin line use to 7.
construct layout work. Construction line
are temporary linework entities that can be used as CUTTING
references when creating and positioning other PLANE LINE- Extra thick lines use to show cutaway
views or plane of projection where a section view is
taken. Arrow indicates the direction of view. Cutting
plane lines mark the point at which the object is to
objects or linework. be cut apart.
3. DIMENSION LINE- Thin and dark lines use to show
the size (span) of an object with a numeric value. Forms of Cutting Plane
Usually terminates with arrowheads or tick markings. There are two forms of cutting plane lines
approved for engineering drawings.
notes or label for size or special information about a
- The first form consists of evenly spaced dashes with feature.
arrowheads indicating the direction of sight.
10. PHANTOM LINE- Long line followed by two short
- The second form consists of alternating long dashes dashes use to show alternate position of a moving
and pairs of short dashes. part.
Cutting Plane Sample:
11. SECTION LINE- Medium lines drawn at 45
degrees use to show interior view of solid areas of
cutting plane line. Represents the part of an object
8. SHORT AND LONG BREAK LINES- Short and long
medium line use to show cutaway view of a long
section.
remaining after a portion is assumed to have been
cut and removed.
Shot Distance and Long Distance Break
9.
LEADER LINE- Medium line with arrowhead to show
