How We Represent Objects Through Drawing Working Document Linguistic review

Technical Drawing – Part of the Design Process  Before something can be produced, it needs to be imagined by someone.  A drawing is a graphic representation of the real thing or idea to be produced.

The Design Process (Giesecke et al. Technical Drawing, 12 th edition. 2000) 1. Problem Identification 2. Concepts and Ideas 3. Compromise solutions 4. Models and/or Prototypes 5. Working drawings for production

Technical Drawings vs. Sketching  Technical Drawing  Used to express technical ideas with precision  Technical Sketching (Diagram)  A freehand expression of graphic language  Tool to quickly express technical ideas.

[MATHEMATICS] the operation by which we make all points on a given surface correspond to a point on another surface; The action of projecting an image on a screen. Projections To project:

PROJECTIONS PARALLEL PROJECTIONS ORTHOGRAPHIC PROJECTIONS CONICAL PROJECTIONS OBLIQUE PROJECTIONS ISOMETRICMULTI-VIEW

The Description of Forms Behind every drawing of an object is space relationship involving four imaginary things: an object; a plane of projection; an observer (the station point); projectors – lines of sight.

Some Types of Projections ISOMETRIC PROJECTIONS CONICAL PROJECTIONS OBLIQUE PROJECTIONS MULTI-VIEW PARALLEL PROJECTIONS ORTHOGRAPHIC PROJECTIONS Let’s look here first

Conical projections  In this type of drawing, the observer is relatively close to the projection plane.  The lines of vision thus form a cone directed towards the observer’s eye.

 In conical projections, the edges which are closer to an observer, are larger compared to the edges which are farther  When drawing conical projections, use at least 2 vanishing points

Types of projections ISOMETRIC PROJECTIONS CONICAL PROJECTIONS OBLIQUE PROJECTIONS MULTI-VIEW PARALLEL PROJECTIONS ORTHOGRAPHIC PROJECTIONS Let’s look here next

Parallel projections In this type of drawing, the observer is infinitely far away. The lines of vision then appear to be parallel.

Types of projections ISOMETRIC PROJECTIONS CONICAL PROJECTIONS OBLIQUE PROJECTIONS MULTI-VIEW PARALLEL PROJECTIONS ORTHOGRAPHIC PROJECTIONS Let’s look here next

Orthographic parallel projections The visual rays are perpendicular to the projection plane, so the projection is said to be orthographic (orthogonal)

Types of projections ISOMETRIC PROJECTIONS CONICAL PROJECTIONS OBLIQUE PROJECTIONS MULTI-VIEW PARALLEL PROJECTIONS ORTHOGRAPHIC PROJECTIONS Let’s look here next

Multi-view orthographic projections

TOP VIEW FRONT VIEW RIGHT SIDE VIEW Here is the usual representation of views in multi-view orthographic projections. This type of drawing is used in technology because it allows description without deforming the faces of objects.

 Top view  Front view, and  Right Side view are three commonly used views in multiview projection

Multi-view orthographic projections Multi-view orthographic projections are a part of parallel projections. In this type of drawing, the observer is considered to be at an infinite distance. The projecting lines are parallel to one another. These projections are also orthographic since both the observer and the object are perpendicular to the projection plane.

Multi-view orthographic projections Another distinguishing element in multi-view projections is that one of the faces of the object to be drawn is placed parallel to the projection plane. That is why, in most cases, one must draw several views of the object to portray it completely. The observer can only see one side at a time.

Multi-view orthographic projections In technical drawing, the views are flat figures (two dimensions) that we see from directly in front of each object. Width Height

Multi-view orthographic projections In the type of projections used in North America, we imagine the object being drawn in the center of a transparent box. The different views of the object are projected onto the sides of this box.

Multi-view orthographic projections One of these views is designated as the front view of the object. We usually choose the face that best portrays the object. The choice of the front view determines the placement of the other views.

Multi-view orthographic projections The projection box and its six views are spread in such a way as to place all the views on the same plane. The other views pivot around the front view. BOTTOM VIEW LEFT SIDE VIEW REAR VIEW FRONT VIEW RIGHT SIDE VIEW TOP VIEW

Multi-view orthographic projections Among the six possible views, we will choose to portray those necessary to the description of the shape of the object. FRONT VIEW RIGHT SIDE VIEW TOP VIEW VUE DE GAUCHE VUE ARRIÈRE BOTTOM VIEW Three views are usually enough to portray an object. Many simple objects may only require one or two views.

Types of projections AXONOMETRIC PROJECTIONS CONICAL PROJECTIONS OBLIQUE PROJECTIONS MULTI-VIEW PARALLEL PROJECTIONS ORTHOGRAPHIC PROJECTIONS Let’s look here next

ISOMETRIC Drawings  In Isometric projection : 1) all three dimensions can be seen in one view 2) the intersecting edges of the object are on the axes that are spread at 120. This way the angles between all intersecting edges are either 120°or 60°.

Isometric projections A cube shown with this type of projection pivots 45º to show three faces on the projection plane instead of a single face. It is then tilted frontward or backward, allowing three faces to be observed.

Types of projections ISOMETRIC PROJECTIONS CONICAL PROJECTIONS OBLIQUE PROJECTIONS MULTI-VIEW PARALLEL PROJECTIONS ORTHOGRAPHIC PROJECTIONS Let’s look here next

Oblique parallel projections  The observer is still at infinite distance, the projecting lines remain parallel to one another, but the object is placed so that the lines of vision are oblique (not perpendicular) to the projection plane.

 OBLIQUE projections are unnatural projections, because the angles and lengths of edges are wrong. It is impossible to actually see objects in this way

 Any drawing that shows all three dimensions (sides) of an object in the same view, is called A PERSPECTIVE DRAWING List all projections that represent a perspective drawing!

(Giesecke et al. Technical Drawing, 12th edition. 2000)

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 Pédagogique 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.

Multi-view orthographic projections TOP VIEW FRONT VIEW RIGHT SIDE VIEW Here is the usual representation of views in multi-view orthographic projections. This type of drawing is used in technology because it allows description without deforming the faces of objects.

Activities with blocks  A series of learning activities were created to give students (and teachers) a better understanding of the four views and placement of objects as well as use of the lines.  We need to review one more thing – line convention before we do these!

CONVENTIONAL LINES Working document Linguistic Review

CONVENTIONAL LINES SUMMARY Portrays surfaces and edges that are hidden from view Indicates the placement of an imaginary cut. Hidden feature line A B C D E F G H NAME PURPOSE THICKNESS J LINE Object line or visible outline Cutting plane line Break line Leader Portrays visible forms. Indicate the surface imagined to have been cut. Used to shorten the view of a part. Indicates the part of a drawing to which a note refers Is used to indicate the dimension. Dimension line Fine Medium Thick Very thick Center line Portrays the center of a round or circular object. Fine Is used to indicate the dimension. Extension line Fine Section lines 100 % 50 % 25 %

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 object above is drawn in isometric projection. It is portrayed on the left by three views. We will use this object to illustrate the principal lines found in technical drawing on the slides which follow. 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 sized, 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 circular or cylindrical shaped objects. The line is half the width of the one used for hidden features. It is a fine line. THE CENTER LINE

CONVENTIONAL LINES D DIMENSION LINE

CONVENTIONAL LINES DIMENSION LINE The dimension line is a fine line ending with an arrow. The purpose of these lines is to provide 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 comment 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

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 TOP VIEW

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

CONVENTIONAL LINES ° 20 Ø 8 FACING Ø14 x 3 DEEP Section 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 Portrays surfaces and edges that are hidden from view Indicates the placement of an imaginary cut. Hidden feature line A B C D E F G H NAME PURPOSE THICKNESS J LINE Object line or visible outline Cutting plane line Break line Leader Portrays visible forms. Indicate the surface imagined to have been cut. Used to shorten the view of a part. Indicates the part of a drawing to which a note refers Is used to indicate the dimension. Dimension line Fine Medium Thick Very thick Center line Portrays the center of a round or circular object. Fine Is used to indicate the dimension. Extension line Fine Section lines 100 % 50 % 25 %