1. CONVENTIONAL LINES Working document Linguistic Review 29-09-07

2. 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

3. CONVENTIONAL LINES A OBJECT LINE OR VISIBLE OUTLINE

4. 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

5. CONVENTIONAL LINES B B HIDDEN FEATURE LINE

6. 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

7. CONVENTIONAL LINES C C THE CENTER LINE

8. 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

9. CONVENTIONAL LINES D DIMENSION LINE

10. 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.

11. 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

12. CONVENTIONAL LINES E 45 80 50 13 40 24 20 40° 20 EXTENSION LINE

13. CONVENTIONAL LINES 45 80 50 13 40 24 20 40° 20 Extension lines are fine lines that indicate the placement of the dimensions. EXTENSION LINE

14. CONVENTIONAL LINES F Ø 8 FACING Ø14 x 3 DEEP 13 40 24 20 40° 20 45 50 80 THE LEADER

15. CONVENTIONAL LINES 45 80 50 Ø 8 FACING Ø14 x 3 DEEP 13 40 24 20 40° 20 The leader is used to indicate the part of the drawing to which a note refers. THE LEADER

16. CONVENTIONAL LINES G 13 40 24 20 40° 20 Ø 8 FACING Ø14 x 3 DEEP 80 45 50 CUTTING PLANE LINE

17. CONVENTIONAL LINES 13 40 24 20 40° 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 80 45 50 CUTTING PLANE LINE

18. CONVENTIONAL LINES 13 40 24 20 40° 20 H Ø 8 FACING Ø14 x 3 DEEP 50 45 80 SECTION LINES

19. CONVENTIONAL LINES 45 13 40 24 20 40° 20 Ø 8 FACING Ø14 x 3 DEEP Sections lines are fine lines used to indicate the surface imagined to have been cut. 50 80 SECTION LINES

20. CONVENTIONAL LINES 50 13 40 24 20 40° 20 H Ø 8 FACING Ø14 x 3 DEEP 45 80 H THE SHORT BREAK LINE

21. CONVENTIONAL LINES 45 80 50 13 40 24 20 40° 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

22. 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

23. CONVENTIONAL LINES SUMMARY

24. 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

25. 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.