Technical drawing uses standardized visual conventions and symbols to unambiguously communicate engineering and design concepts. It is considered essential for industry. The international standard ISO 128 codifies common principles, such as types of lines and projection views. Technical drawing aims for objective, single interpretations compared to the subjective nature of artistic drawing. Draftspeople create technical drawings according to standardized guidelines for dimensions, projections, and different line types that indicate visible, hidden, cut, and other features of a design.

2. INTERPRET DRAWING AND
PLANS

3. Technical drawing

4. Technical drawing

5. What is TECHNICAL
DRAWING?

6. Technical drawing is essential for
communicating ideas in industry
and engineering.

7. Why is it
ESSENTIAL?

8. Essential, because
 To make the drawings easier to understand,
people use familiar symbols, perspectives, units
of measurement, notation systems, visual styles,
and page layout.

9.  Together, such conventions constitute a visual language and help
to ensure that the drawing is unambiguous and relatively easy to
understand.
 Many of the symbols and principles of technical drawing are
codified in an international standard called ISO 128.
 ISO 128 - is an international standard issued by International
Organization for Standard [ISO 128].
• General principles of presentation in technical drawings.
• It describes basic conventions for ; lines, views, cuts and section,
and different types of engineering drawings like;
• Mechanical engineering
• Architecture
• Civil engineering
• and shipbuilding
- It’s applicable to both manual computer-based-drawing

10. The ISO 128

11.  The need for precise communication in the preparation of
a functional document distinguishes technical drawing
from the expressive drawing of the visual arts.
 Artistic drawings are subjectively interpreted; their
meanings are multiply determined.
 Technical drawings are understood to have one intended
meaning.
 A drafter, draftsperson, or draftsman is a person who makes
a drawing (technical or expressive).
 A professional drafter who makes technical drawings is
sometimes called a drafting technician.

12. Definition of Terms
 Axis- line about which a body turns or rotates .
 Design - drawing showing the plan, elevations, sections, and other features.
 Detail drawing - separate drawing showing a small part of a machine or
structure.
 Dimension - definite measure shown on a drawing in detail.
 Isometric Drawing - drawing which resembles a respective drawing.
 Orthographic Projection - arrangement in a drawing of the three principal
views of an object.

13. Definition of Terms
Perspective Drawing - the representation of an object on a plan surface,
pertaining to materials, styles and finish presented as to have the same
appearances as when seen from a particular viewpoint.
Projections - the cutting out of any part or any member of a structure.
Reduced - made smaller than the actual size as in the size of object.
Scaled Drawing - drawing plan made according to a scale, smaller than the
actual work.
Sketch - freehand drawing of an object.
Specification - written instruction to the worker containing all the
information.

14. Alphabet of Lines
- In sketching orthographic drawing, certain
conventional lines are used for a definite purpose .
These lines are commonly called Alphabet of Lines.

15. Alphabet of Lines
1. Visible line
2. Hidden Line
3. Section Line
4. Center Line
5. Dimension line
6. Extension line
7. Leader line
8. Cutting Plane or viewing plane lines
9. Break lines (short break, long break and
cylindrical break)
10. Phantom line

16. Alphabet of Lines

17. Alphabet of Lines
1. Visible line

18. Alphabet of Lines
2 . Hidden line

19. Alphabet of Lines
3. Section line

20. Alphabet of Lines
4. Center line

21. Alphabet of Lines
5. Dimension line

22. Alphabet of Lines
6. Extension line

23. Alphabet of Lines
7. Leader line

24. Alphabet of Lines
8. Cutting plane or viewing plane line

25. Alphabet of Lines
9. Break lines ( short break, long break and cylindrical
break)

26. Alphabet of Lines
10. Phantom line

27. Thank you!!!