Page 27 - Engineering drawing from first principles using AutoCAD

20 Engineering drawing [rom first principles

industry and commerce have developed established practices and standards and your
local Reference Library is an ideal source of information. The following notes are
included here for background reading and information.

BS and ISO Drawing Standards cater for all drawings no matter how they are prepared.
The Standards do not differentiate between drawings produced by electronic means, ink
tracings or pencil drawings.
CAD linework is black and dense and what you see on the screen is exactly what the
printer or plotter will reproduce. There are no problems with line density and variable

Table 1.1

Line Description Application
A Continuous thick A1 Visible outlines
A2 Visible edges
8 Continuous thin 81 Imaginary lines of intersection
82 Dimension lines
83 Projection lines
84 Leader lines
85 Hatching
86 Outlines of revolved sections
87 Short centre lines
C Continuous thin 1C1 Limits of partial or interrupted views and
~ irregular sections, if the limit is not an axis
D Continuous thin 2D1 Limits of partial or interrupted views and
~ straight with zigzags sections, if the limit is not an axis

E Dashed thick E1 Hidden outlines
------- E2 Hidden edges
F Dashed thin" F1 Hidden outlines
------- F2 Hidden edges

G Chain thin G1 Centre lines
G2 Lines of symmetry
------- G3 Trajectories and loci
G4 Pitch lines and pitch circles
H 1---- Chain thin, thick at H1 Cutting planes
ends and changes of
I
direction
I
I
_-----.J
J Chain thick J1 Indication of lines or surfaces to which a
-------- special requirement applies (drawn adjacent
to surface)
K Chain thin double K1 Outlines and edges of adjacent parts
dashed K2 Outlines and edges of alternative and extreme
-------- positions of movable parts
K3 Centroidal lines
K4 Initial outlines prior to forming
4K5 Parts situated in front of a cutting plane
K6 8end lines on developed blanks or patterns

Notes
1 The lengths of the long dashes shown for lines G, H, J and K are not necessarily typical due to the confines
of the space available.
2 This type of line is suited for production of drawings by machines.
3 The thin Ftype line is more common in the UK, but on anyone drawing or set of drawings only one type of
dashed line should be used.
4 Included in ISO 128-1982 and used mainly in the building industry.