CONVENTIONAL LINES Working document Linguistic Review

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. 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 B B 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 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 ° The dimension is a value used to indicate size in a technical drawing. This value is given in millimetres. DIMENSION

CONVENTIONAL LINES E ° 20 EXTENSION LINE

CONVENTIONAL LINES ° 20 Extension lines are fine lines that indicate the placement of the dimensions. EXTENSION LINE

CONVENTIONAL LINES F Ø 8 FACING Ø14 x 3 DEEP ° THE LEADER

CONVENTIONAL LINES Ø 8 FACING Ø14 x 3 DEEP ° 20 The leader is used to indicate the part of the drawing to which a note refers. THE LEADER

CONVENTIONAL LINES G ° 20 Ø 8 FACING Ø14 x 3 DEEP CUTTING PLANE LINE

CONVENTIONAL LINES ° Ø 8 FACING Ø14 x 3 DEEP The cutting plane line is very thick; this line is used to designate where an imaginary cut took place. INFORMATION ON CUTS CUTTING PLANE LINE

CONVENTIONAL LINES ° 20 H Ø 8 FACING Ø14 x 3 DEEP SECTION LINES

CONVENTIONAL LINES ° 20 Ø 8 FACING Ø14 x 3 DEEP Sections lines are fine lines used to indicate the surface imagined to have been cut SECTION LINES

CONVENTIONAL LINES ° 20 H Ø 8 FACING Ø14 x 3 DEEP H THE SHORT BREAK LINE

CONVENTIONAL LINES ° 20 Ø 8 FACING Ø14 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

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. SUMMARY

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.