418 Machine Drawing
dharm
d:\N-Design\Des21-1.pm5
80
Horizontal
60 20
Continuing
60
Vertical
85
50
Base line dimension
Diameter
Leader dimension
f 30
45°
Angular
75
Aligned dimension Radius
R45
f 50
Fig. 21.19
2. Angular — is used to dimension angles. Here, one has to select two non-parallel
lines to introduce the angular dimension.
3. Diameter — this can be invoked for dimensioning arcs and circles.
4. Radius — it is almost identical to diameter dimensioning, except that only a
radius line is drawn. This line has only one arrow.
5. Associative — used to make various changes to associative dimension entities.
6. Dimensioning utility commands
— to draw a centre line or centre mark for a circle/arc, this command is
used.
AutoCAD generally uses same type of dimensions and dimension label components as standard
draughting. Figure 21.19 gives examples of types of dimensions possible: linear, angular,
diametric, radial and aligned. A number of variables such as extension lines, text location,
tolerance specifications, arrow styles and sizes, etc., actually control the way in which the
dimensions may appear in the drawings.
21.16.1 Dimensioning Fundamentals
The student is already exposed to some definitions of fundamentals. However, the following are
specific for AutoCAD: (i) Base line dimension-a series of dimension lines, all starting at the
same extension line, that measure successive linear distances. (ii) Continuing dimension—a
series of dimension lines that follow one another along successive linear distances.
21.16.2 Dimensioning Methods
The procedure to be followed for dimensioning in AutoCAD is as follows:
