CE101
Engineering Drawing
Lec1: Introduction and Basics
Part-2: Dimensioning and Scales
Indian Institute of Technology
Guwahati
,Wednesday, October 27, 2 CE101 Lec1: Introduction and Basics 2
021
,Dimensioning
Dimension is a numerical value expressed in appropriate units of
measurement and indicated graphically on technical drawings with
lines, symbols and notes (BIS SP 46: 2003)
Dimensioning is done by a set of extension lines, dimension lines,
leader lines, arrow heads and dimensions
Symbol for diameter
Unit of length
mostly in millimeter
Angles in degrees
Symbols to indicate
specific geometry
Wednesday, October 27, 2 CE101 Lec1: Introduction and Basics 3
021
, Dimension line: Dimension line is a thin continuous line. It is terminated
by arrowheads touching the outlines, extension lines or centre lines
Extension lines: An extension line is also a thin continuous line drawn in
extension of on outline. It extends by about 3 mm beyond the dimension line
Arrowheads: An arrowhead is placed at each end of a dimension line. Its
pointed end touches an outline, an extension line or a center line. The size
of an arrowhead should be proportional to the thickness of the outlines. The
length of the arrowhead should be about three times its maximum width
Leader: A leader or a pointer is a thin continuous line connecting a note or
a dimension figure with the feature to which it applies.
Wednesday, October 27, 2 CE101 Lec1: Introduction and Basics 4
021
Engineering Drawing
Lec1: Introduction and Basics
Part-2: Dimensioning and Scales
Indian Institute of Technology
Guwahati
,Wednesday, October 27, 2 CE101 Lec1: Introduction and Basics 2
021
,Dimensioning
Dimension is a numerical value expressed in appropriate units of
measurement and indicated graphically on technical drawings with
lines, symbols and notes (BIS SP 46: 2003)
Dimensioning is done by a set of extension lines, dimension lines,
leader lines, arrow heads and dimensions
Symbol for diameter
Unit of length
mostly in millimeter
Angles in degrees
Symbols to indicate
specific geometry
Wednesday, October 27, 2 CE101 Lec1: Introduction and Basics 3
021
, Dimension line: Dimension line is a thin continuous line. It is terminated
by arrowheads touching the outlines, extension lines or centre lines
Extension lines: An extension line is also a thin continuous line drawn in
extension of on outline. It extends by about 3 mm beyond the dimension line
Arrowheads: An arrowhead is placed at each end of a dimension line. Its
pointed end touches an outline, an extension line or a center line. The size
of an arrowhead should be proportional to the thickness of the outlines. The
length of the arrowhead should be about three times its maximum width
Leader: A leader or a pointer is a thin continuous line connecting a note or
a dimension figure with the feature to which it applies.
Wednesday, October 27, 2 CE101 Lec1: Introduction and Basics 4
021
