بسم الله الرحمن الرحيم

Projection Theory Projection is a method to represent 3D object into 2D plane(paper…etc.) Object View Therefore we need at least tow or three views (except for especial cases)

The projection theory is based on 3 variables: 3- Plane of projection Therefore View is the image on a projection plane 1- center sight point(station point) 2- Line of sight

Lines of Convergent Projection Parallel Projection Play

The parallel projection lines can be normal (orthogonal) or oblique to the plane of projection. Oblique مائل Orthogonal متعامد Play We consider only a parallel and orthogonal projection, i.e. orthographic projection.

Rotation دوران Tilting امالة View depends on a relative orientation between an object and a plane. Normal عمودى

Projections Convergent Parallel OrthogonalOblique AxonometricMultiview Pictorial drawing Perspective Drawing Multiview drawing

PROJECTION METHOD Perspective Oblique Orthographic Axonometric Multiview Parallel

First angle method Third angle method First quadrant Third quadrant -European countries - ISO standard - Canada, USA - Japan, Thailand Transparent Planes مستويات شفافة Opaque Planes مستويات غير شفافة

First angle system (Opaque planes) Third angle system (transparent planes/glass box)

Folding line Folding line  Third angle system First angle system Cutting Line Cutting Line 

FRONT VIEW LEFT SIDE VIEW TOP VIEW LEFT SIDE VIEW FRONT VIEW TOP VIEW

d 1.7d 2.2d

Depth Width Height Depth Width Height Depth Height

Projections of points, lines and planes

NOTATIONS FOLLOWING NOTATIONS SHOULD BE FOLLOWED WHILE NAMEING DIFFERENT VIEWS IN ORTHOGRAPHIC PROJECTIONS. IT’S FRONT VIEW a’ b’ SAME SYSTEM OF NOTATIONS SHOULD BE FOLLOWED INCASE NUMBERS, LIKE 1, 2, 3 – ARE USED. OBJECT POINT A LINE AB IT’S TOP VIEW a a b IT’S SIDE VIEW a” b”

A a a’ A a A a X Y X Y X Y For Fv For Tv For Fv For Tv For Fv POINT A ABOVE HP & INFRONT OF VP POINT A IN HP & INFRONT OF VP POINT A ABOVE HP & IN VP PROJECTIONS OF A POINT IN FIRST QUADRANT PICTORIAL PRESENTATION PICTORIAL PRESENTATION ORTHOGRAPHIC PRESENTATIONS OF ALL ABOVE CASES. XY a a’ VP HP XY a’ VP HP a XY a VP HP a’ Fv above xy, Tv below xy. Fv above xy, Tv on xy. Fv on xy, Tv below xy.

SIMPLE CASES OF THE LINE 1.A VERTICAL LINE ( PERPENDICULAR TO HP & // TO VP) 2.LINE PARALLEL TO BOTH HP & VP. 3.LINE INCLINED TO HP & PARALLEL TO VP. 4.LINE INCLINED TO VP & PARALLEL TO HP. 5.LINE INCLINED TO BOTH HP & VP. STUDY ILLUSTRATIONS GIVEN ON NEXT PAGE SHOWING CLEARLY THE NATURE OF FV & TV OF LINES LISTED ABOVE AND NOTE RESULTS. PROJECTIONS OF STRAIGHT LINES INFORMATION REGARDING A LINE means IT’S LENGTH, POSITION OF IT’S ENDS WITH HP & VP IT’S INCLINATIONS WITH HP & VP WILL BE GIVEN. AIM:- TO DRAW IT’S PROJECTIONS - MEANS FV & TV.

X Y V.P. X Y b’ a’ b a F.V. T.V. a b a’ b’ B A TV FV A B XY H.P. V.P. a’ b’ a b Fv Tv XY H.P. V.P. a b a’b’ Fv Tv For Fv For Tv For Fv Note: Fv is a vertical line Showing True Length & Tv is a point. Note: Fv & Tv both are // to xy & both show T. L A Line perpendicular to Hp & // to Vp A Line // to Hp & // to Vp Orthographic Pattern (Pictorial Presentation)

A Line inclined to Hp and parallel to Vp (Pictorial presentation) X Y V.P. A B b’ a’ b a   F.V. T.V. A Line inclined to Vp and parallel to Hp (Pictorial presentation) Ø V.P. a b a’ b’ B A Ø F.V. T.V. XY H.P. V.P. F.V. T.V. a b a’ b’  XY H.P. V.P. Ø a b a’b’ Tv Fv Tv inclined to xy Fv parallel to xy Fv inclined to xy Tv parallel to xy. Orthographic Projections

X Y V.P. For Fv a’ b’ a b B A   For Tv F.V. T.V. X Y V.P. a’ b’ a b   F.V. T.V. For Fv For Tv B A X Y   H.P. V.P. a b FV TV a’ b’ A Line inclined to both Hp and Vp (Pictorial presentation) 5. Note These Facts:- Both Fv & Tv are inclined to xy. (No view is parallel to xy) Both Fv & Tv are reduced lengths. (No view shows True Length) Note These Facts:- Both Fv & Tv are inclined to xy. (No view is parallel to xy) Both Fv & Tv are reduced lengths. (No view shows True Length) Orthographic Projections Fv is seen on Vp clearly. To see Tv clearly, HP is rotated 90 0 downwards, Hence it comes below xy. On removal of object i.e. Line AB Fv as a image on Vp. Tv as a image on Hp,

TOP VIEW FRONT VIEW SIDE VIEW

TOP VIEW FRONT VIEW SIDE VIEW

TOP VIEW FRONT VIEW SIDE VIEW

TOP VIEW FRONT VIEW SIDE VIEW

TOP VIEW FRONT VIEW SIDE VIEW

TOP VIEW FRONT VIEW SIDE VIEW

TOP VIEW FRONT VIEWSIDE VIEW

FRONT VIEW SIDE VIEW TOP VIEW

FRONT VIEW TOP VIEW SIDE VIEW

FRONT VIEW TOP VIEW

Procedure 1. Decide the suitable number of views 2. Layout the decided views on a drawing sheet. 3. Draw details of each selected views. 4. Write dimensions and, if any, notes Top Front Choose a drawing scale (say 1:1) Top Front y y x x x x y y z

The longest dimension of an object should be presented as a width (in an front view). Inappropriate First choice Second choice appropriate It requires More space It requires less space

Inappropriate 2. The adjacent views projected from the selection elevation view should be appeared in a natural position.

3. It has the fewest number of hidden lines. GoodInappropriate

1. Choose the adjacent view that has the fewest number of hidden lines.

2. Choose the minimum number of views that can represent the major features of the object. Necessary NOT GOOD - Hole’s information is placed on a separated view. GOOD -All hole’s information is placed on a single view. FRONT VIEW TOP VIEW RIGHT SIDE VIEW

3. Choose the views that are suitable to a drawing sheet. Good Poor Not enough space for dimensioning. Good Choose another adjacent view. Change orientation of the selected views.

1.Generally, three views of orthographic drawing are enough to describes an object’s information. 2. In some specific cases, a necessary view may be less or more than three views.

1. Flat (thin) part having a uniform thickness such as a gasket, sheet metal etc. Adjacent views provide only a part’s thickness ! 1 Thick Example

Repeat ! Deduce from center line Cylindrical-shaped part.

1. Identical adjacent view exists. Repeat ! 2. The 3 rd view provides no additional information

1. Identical view exists.

2. The 3 rd view provides no additional information

ELEV. VIEW PLANE VIEW SIDE VIEW FOR E.V. FOR S.V. FOR P.V.

FOR E.V. FOR S.V. FOR P.V. ELEV. VIEW PLANE VIEW SIDE VIEW

FOR P.V. FOR E.V. FOR S.V. ELEV. VIEW PLANEVIEW SIDE VIEW

Multiview Projection No line should be drawn where a curved surface is tangent to a plane surface. When a curved surface intersects a plane surface a definite edge is formed. Show are examples of intersections and tangencies.

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