This document defines and describes different types of lines used in technical drawings. It discusses visible and hidden object lines, dimension lines, extension lines, center lines, leader lines, cutting plane lines, reference lines, repeated/ditto lines, break lines, and hatching lines. For each line type, it provides details on the line weight, style, and purpose. The document serves as a reference for the proper application of various line types in technical drawings.

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ALPHABET OF LINES
- s
DIFFERENT TYPES OF LINES
 It is a thick full line. It is used to represent all visible
edges of an object.
VISIBLE / OBJECT LINE
- s
DIFFERENT TYPES OF LINES
 It is a medium short dash lines approximately 1/8
inches in length and spaced 1/32 inches between the
lines.
 It is used to represent hidden or unseen edges of an
object.
INVISIBLE / HIDDEN LINE
- s
DIFFERENT TYPES OF LINES
 It is a thin, fine, dark, and solid line with arrowheads on
both ends.
 It indicate the direction and the length of an object
DIMENSION LINE
10 m
- s
DIFFERENT TYPES OF LINES
 It is also called projection or witness line.
 It is a thin, dark and solid line that extends from a point
on the drawing to which a dimension refers.
 A gap of about 1/16 inches should be left where the
extension would join the object line.
EXTENSION LINE

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- s
DIFFERENT TYPES OF LINES
 It is a thin line with long and
short dashes drawn alternately
which is used to indicate the
axis of symmetry.
 The short dashes should be
about 1/16 inches and the
centerlines should start at the
end with the long dashes.
CENTER LINE
- s
DIFFERENT TYPES OF LINES
 It is a thin-straight line from a dimension value or
explanatory note on the feature of the drawing.
LEADER LINE
10mm
diameter bolt
- s
DIFFERENT TYPES OF LINES
 It is a thick line consists of alternate long and short
dashes.
 It is used to show the path of plane of a cut object.
CUTTING PLANE LINE
- s
DIFFERENT TYPES OF LINES
 It is a thin-curved irregular line with arrowhead similar
to a leader line.
 It is used to give an explanatory note about the
dimension of an object.
REFERENCE LINE
- s
DIFFERENT TYPES OF LINES
 It is a medium weight line consists of two dashes drawn
repeatedly.
 The dashes are 1/8 inches long and 1/32 inches gap
between them and 3/15 inches gap between the dashes.
Repeated / ditto line
- s
DIFFERENT TYPES OF LINES
 It is classified in to two.
(a) Long Break Lines
- to show that an object has been cut.
(b) Short Break Lines
- to show that part of an object is not large.
BREAK LINES

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- s
DIFFERENT TYPES OF LINES
 It is a thin line drawn 45 degrees with 1/16 inches
between the lines.
 It is used to indicate that part of the object has been
removed.
HATCHING LINE