2TOPICS Definition Purposes Types of conventions - Alternate position of side view - Incompleted view - Aligned view - Enlarged view - Non-existing intersection line - Cylinder intersection
3DEFINITIONConvention is a commonly accepted practices which disregard some strict rules of orthographic projection.More readablemultiviewrepresentationObjectMultiviewrepresentationProjection’ srulesConventionpracticesDisregardsome rules
4EXAMPLE : Already met convention practice Front viewUsing a dash line for representing the hidden edge.CONVENTIONPRACTICE
5PURPOSES To improve the clarity of a drawing. To facilitate the dimensioning.To reduce the drafting effort.To save or efficiently use a drawing space.
6TYPES OF CONVENTION PRACTICE 1. Alternate position of side view2. Incompleted view2.1 Incompleted side view2.2 Partial view2.3 Half view2.4 Local view
7TYPES OF CONVENTION PRACTICE 3. Aligned view4. Enlarged view5. Non-existing intersection line6. Intersection : Hole on a cylinder
9ALTERNATE POSITION OF SIDE VIEW PurposesTo save drawing space.To improve the clarity of a drawing.Conventional practiceWhenever the height of an object is small and thedepth is relatively large, places the side view besidethe top view.
13DEFINITION Incompleted side views are side views that are eliminated a feature that can not clearlyseen from a selected viewing direction.
14Difficult to read and to dimension. Example : Strictly orthographic projection.Left-side viewPrincipal viewRight-side viewDetails are interfered by thoseon the opposite view.Difficult to read and to dimension.
15Example : Incompleted side views left-side viewIncompletedright-side viewPrincipal viewBetter describe an object andfacilitate dimensioning.
16Example : Incompleted side views representation Principal view
18DEFINITION Partial view is a view that represents portions of the part that have a features need to clarify.Half view is a partial view that is illustrated only half of the part.Local view is a view that shows only features need to clarify.
20Center line acts as a line of symmetry. Example : Half viewLeft halfRight halfCenter line acts as a line of symmetry.No continuous line !Symmetry symbolThin line (4H)
21In this course, we omit the break line. Example : Half view : alternative representationHalf view can be made by drawing the viewsslightly beyond the line of symmetry.No symmetry symbol.It is allow for writinga break line.Thin line (4H)In this course, we omit the break line.
36DEFINITION Conventional practice Enlarged view is a view partly selected fromfull view and is drawn with a larger scale.Conventional practiceAt full view, the selected portion is framed by continuous thin line and having a name.For an enlarged view, it must be specified both name and scale used.
37Example : Enlarged view Full viewEnlarged vieworAA (3:1)A (3:1)ReferencepositionScale
39DEFINITION Conventional practice Non-existing line of intersection is the line ofintersecting surfaces that are eliminated by filletsand rounds.Conventional practiceWhen true projection mislead the representationof an object, it is necessary to show the additionallines that are projected from the actual intersectionof the surfaces as if the fillets and rounds werenot present.
40Example : Non-existing line of intersection Object does not hasrounds and filletsEdges of the surfacesare shown as lines inthe top view.
41Example : Non-existing line of intersection Object hasrounds and filletsThe view looks like a platewith a hole !!Convention practice required !Construct a non-existing line of intersection.No edge !(No intersection between surfaces)