conventional lines working document linguistic review 29-09-07
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CONVENTIONAL LINES
Working documentLinguistic Review 29-09-07
CONVENTIONAL LINES
In a technical drawing, each type of line has its own significance. Each is distinguished from the other by a particular thickness or shape.
The thrust equipped with two lathed holes drawn above in isometric projection, is also portrayed on the right by three views. This drawing will serve to illustrate, in the following pages, the principal lines found in technical drawing.
8 -
LAMAGE
14 X 3 PROF.
45°
13
20
50
40
20
24
45
80
FACING
DEEP
CONVENTIONAL LINES
A
OBJECT LINE OR VISIBLE OUTLINE
CONVENTIONAL LINES
The object line or visible outline is made of a continuous line that portrays the visible forms of the object.
It is a thick line, its thickness chosen to clearly show the shape.
OBJECT LINE OR VISIBLE
OUTLINE
CONVENTIONAL LINES
BB
HIDDEN FEATURE LINE
CONVENTIONAL LINES
B
The hidden feature line is made of a dashed line that portrays surfaces and edges that are hidden from view.
The line is medium, half the width of the one chosen for the visible outline.
HIDDEN FEATURE LINE
CONVENTIONAL LINES
C
C
THE CENTER LINE
CONVENTIONAL LINES
The center line is made from phantom lines. It is used to designate the axes of round or symmetrically shaped objects.
The line is fine, the width half that of the one used for hidden features.
THE CENTER LINE
CONVENTIONAL LINES
D
DIMENSION LINE
CONVENTIONAL LINES
DIMENSION LINEDIMENSION LINE
The dimension line is a fine line ending with an arrow.
Its purpose is to enter and specify the placement of the dimensions.
CONVENTIONAL LINES
45
80
40 20
40°
The dimension is a value used to indicate size in a technical drawing.
This value is given in millimetres.
DIMENSION
CONVENTIONAL LINES
E
45
80
50
1340
2420
40°
20
EXTENSION LINE
CONVENTIONAL LINES
45
80
50
1340
2420
40°
20
Extension lines are fine lines that indicate the placement of the dimensions.
EXTENSION LINE
CONVENTIONAL LINES
F
Ø 8FACINGØ14 x 3 DEEP
1340
2420
40°
20
45
50
80
THE LEADER
CONVENTIONAL LINES
45
80
50
Ø 8FACINGØ14 x 3 DEEP
1340
2420
40°
20
The leader is used to indicate the part of the drawing to which a note refers.
THE LEADER
CONVENTIONAL LINES
G
1340
2420
40°
20
Ø 8FACINGØ14 x 3 DEEP
80
45
50
CUTTING PLANE LINE
CONVENTIONAL LINES
1340
2420
40°
Ø 8FACINGØ14 x 3 DEEP
The cutting plane line is very thick; this line is used to designate where an imaginary cut took place.
INFORMATION ON CUTSINFORMATION ON CUTS
80
45
50
CUTTING PLANE LINE
CONVENTIONAL LINES
1340
2420
40°
20
H
Ø 8FACINGØ14 x 3 DEEP
50
45
80
SECTION LINES
CONVENTIONAL LINES
45
1340
2420
40°
20
Ø 8FACINGØ14 x 3 DEEP
Sections lines are fine lines used to indicate the surface imagined to have been cut.
50
80
SECTION LINES
CONVENTIONAL LINES
50
1340
2420
40°
20
HØ 8FACINGØ14 x 3 DEEP
45
80
H
THE SHORT BREAK LINE
CONVENTIONAL LINES
45
80
50
1340
2420
40°
20
Ø 8FACINGØ14 x 3 DEEP
The short break line is a thick, irregular line used to indicate a partial cut. This line is drawn freehand.
THE SHORT BREAK LINE
The long break line is a fine line used to shorten the view of a long part that can not be shown full length.
THE LONG BREAK LINE
CONVENTIONAL LINES
SUMMARY
Portrays surfaces and edges that are hidden from view
Indicates the placement of an imaginary cut.
Hidden feature line
A
B
C
D
E
F
G
H
NAME PURPOSE THICKNESS
J
LINE
Object line or visible outline
Cutting plane line
Break line
Leader
Portrays visible forms.
Indicate the surface imagined to have been cut.
Used to shorten the view of a part.
Indicates the part of a drawing to which a note refers
Is used to indicate the dimension. Dimension line Fine
Medium
Thick
Very thick
Center line Portrays the center of a symmetrical
object. Fine
Fine
Fine
Fine
Is used to indicate the dimension. Extension line Fine
Section lines
100 %
50 %
25 %
The cutting plane line show where the object is cut. The arrows indicate the point of view of the observer.
The section view allows one to see inside the object. It makes the object simpler to understand by eliminating hidden feature lines.
We presume that the part between the cutting plane line and the observer has been removed.
The section is drawn in a view adjacent to the cutting plane line.
Section lines emphasise which part has been cut in the section view.
SUMMARYSUMMARY
Bibliography
GIESECKE, Frederick E., MITCHELL, Alva, SPENCER, Henry Cecil, HILL, Ivan Leroy, GYGDON, John Thomas et NGUYEN, Dinh N. « Dessin technique », Montréal, Éditions du Renouveau Pédagogiques inc., 1982, 769 p.
JENSEN, C.H. « Dessin industriel », Montréal, McGraw-Hill, 1972, 752 p.
STIRLING, Norman. « Éléments de dessin industriel », Montréal, HRW, 1979, 372 p.