theory of projection Presentation (1&2).pptx

This document, contains the introduction and brief explanation of the theory of projection. and this is for All Engineering students who are currently persuing this undergraduate level

1. Mattu University Collage of Engineering and Technology Department of Mechanical Engineering 2018/2025 A.Y Prepared by Lami B . Course: Engineering Drawing (MEng 2061)

2. Engineering Drawing (MEng 2061) Introduction Projection Multi-View Drawing Pictorial Drawing Auxiliary Views Sectional Views Course contents: by Lami B 2

3. Introduction: is a graphic representation of an object, or a part of it, and is the result of creative thought by an engineer or technician . Is One of the most widely used forms of graphic communication A graphical representation of an idea, concept or an entity which actually or potentially exists in life. Drawing by Lami B 3 Drawings Photographs Slides Transparencies and sketches FGC

4. DRAWING Artistic Drawing Regardless of their complexity, artistic drawings are used to express the feelings, beliefs, philosophies, and ideas of the artist . does not contains dimensions, notes and specifications. Technical (Engineering) Drawing s A technical drawing is a means of clearly and concisely communicating all of the information necessary to transform an idea or a concept in to reality contains dimensions, notes and specifications. by Lami B 4

5. Cont.… by Lami B 5 Artistic Drawings Technical (Engineering) Drawings Jenson,Cecil Howard, Engineering drawing and design,1925,4 th ed., Macmillan/McGram-Hill

6. Engineering drawing is a two dimensional representation of three dimensional objects It is the graphic language from which a trained person can visualize objects. is called the universal language of engineers. In general, it provides necessary information about the shape , size , surface quality , material , manufacturing process , etc., of the object. by Lami B 6

7. Role of Engineering Drawing: by Lami B 7 The ability to read drawing is the most important requirement of all technical people in any profession. As compared to verbal or written description, this method is brief and more clear. The subject in general is designed to impart the following skills. Ability to read and prepare engineering drawings. Ability to make free - hand sketching of objects. Power to imagine, analyses and communicate, and Capacity to understand other subjects.

8. Some of the applications are: by Lami B 8 Machine drawing for mechanical engineers Building drawing for civil engineers Circuit diagrams for electrical and electronics engineers, Computer graphics for one and all.

9. by Lami B 9 Ships Manufacturing of Automobiles Construction Aerospace Industries

10. Drawing Instruments: by Lami B 10 Drawing board Mini draughter Instrument box Set squares ( )   5. Protractor 6. Set of scales 7. French curves 8. Drawing sheets 11. Compass 12. Pencil Sharpener 15. Eraser 16. Sketch book 9. Pencils 10. Template 13. Roller scale 14. Large size divider Some of the drawing instruments are listed below

11. Drawing Sheet: by Lami B 11

12. Drawing Sheet Layout (Is 10711 : 2001) by Lami B 12 The layout of a drawing sheet used on the shop floor

13. Cont.… by Lami B 13 The layout of a drawing sheet used for class work

14. Title Block by Lami B 14 1 . Title of the drawing. 2. Drawing number. 3. Scale. 4. Symbol denoting the method of projection. 5. Name of the firm, and 6. Initials of staff who have designed, checked and approved The title block should lie within the drawing space at the bottom right hand corner of the sheet The title block can have a maximum length of 170 mm providing the following information.

15. by Lami B 15 Title block sample Note: All dimensions are in mm

16. Reading Assignment by Lami B 16 Line Lettering Dimensioning Scale Principles of Dimension Execution of Dimensions Methods of Indicating Dimensions Arrangement of Dimensions

17. THEORY OF PROJECTION by Lami B 17 The projection theory is used to graphically represent 3-D objects on 2-D media (paper, computer screen). The projection theory is based on two variables: Line of sight Plane of projection (image plane or picture plane) Line of sight (LOS) is an imaginary ray of light between an observer’s eye and an object.

18. by Lami B 18 There are 2 types of LOS : parallel and converge

19. by Lami B 19 Plane of projection is an imaginary flat plane on which the image is created. Type equation here.  

20. by Lami B 20

21. by Lami B 21 perspective projection: The projection lines (visual rays) converge to a point. The image is larger or smaller than the real object. Perspective projection  is not suitable for working drawing because a  perspective view  does not give exact size and shape

22. by Lami B 22 Pictorial Projection: The Projection in which the length, breadth (width) and height of an object is shown in one view is known as pictorial projection

23. by Lami B 23 Orthographic  projection: The projecting lines are parallel to each other and perpendicular to the plane of projection The resulting projection views are the same size and shape as the front surface of object This is the most applicable type of projection technique

24. by Lami B 24 Orthographic Projections is a technical drawing in which different views of an object are projected on different reference planes observing perpendicular to respective reference plane. Different Reference planes are: Horizontal Plane (HP) Vertical Plane (VP) Side or Profile Plane (PP) Different views are: Front View (FV) – Projected on VP Top View (TV) – Projected on HP Side View (SV) – Projected on PP

25. by Lami B 25 The most common means of understanding of orthographic projection is The Glass Box method .

26. by Lami B 26 Opening the Box

27. First and Third Angle Projections FIRST ANGLE PROJECTION The object is assumed to be situated in the first quadrant. The object lies in between the observer and the plane of projection View from above (top view) is drawn below of front view View from left (left side view) is drawn on the right of front view View from right (right side view) is drawn on left of front view. THIRD ANGLE PROJECTION The object is assumed to be situated in the third quadrant The plane of projection lies in between the observer and the object View from above (top view) is drawn above of front view View from left (left side view) is drawn on the left of front view View from right (right side view) is drawn on right of front view by Lami B 27

28. by Lami B 28

29. by Lami B 29 Orthographic views

30. by Lami B 30 Orthographic views

31. by Lami B 31 Views arrangement

32. by Lami B 32 Projection symbols