Orthographic Writing Properties

Suggestions : Orient the object1. The object should be placed in its natural position.NO !2. The orthographic views should represent the true size and true shape of an object (as much as possible).GOODPrimaryauxiliary view

Contents

OrthographicwritingContentsBasicdimensioning

ContentsView selection procedures1. Orient the object to the best position relative to a glass box. 2. Select the front view.3. Select adjacent views.Suggestions : Select the front view1. The longest dimension of an object should be presented as a width (in a front view).

InappropriateFirst choiceGoodSecond choiceUse more space

Inappropriate2. The adjacent views project from the selected front view should be appeared in a natural position.Suggestions : Select the front view3. It has the fewest number of hidden lines.

GoodInappropriate

Suggestions : Select the front viewSuggestions : Select an adjacent viewInappropriate

Inappropriate1. Choose the 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.

NecessaryNecessaryHoles information is placed on a separated view.Suggestions : Select an adjacent viewAll information is placedon a single view.3. Choose the views that are suitable to a drawing sheet.GoodSuggestions : Select an adjacent viewPoorNot enough spacefor dimensioning.GoodChoose another adjacent view.Change orientation of theselected views.SummaryView selection has 3 stepsIn practice, drafter should consider all recommendationssimultaneously before start to draw.Orientthe objectSelectfront viewSelectadjacent view

Additional examples on a view selectionContentsNotesGenerally, three views orthographic drawingis selected to describes an objects information.In some specific case, a necessary view may be less or more than three views.Later chapterObject that requires only one-viewFlat (thin) part having a uniform thickness such as a gasket, sheet metal etc.Adjacent views provide only aparts thickness !1 ThickCylindrical-shaped part.ExampleRepeat !Infer from CLObject that requires only one-viewExampleExampleFlat (thin) part having a uniform thickness such as a gasket, sheet metal etc.Cylindrical-shaped part.Identical adjacent view exists.Repeat !Object that requires only two-viewThe 3rd view has no significant contours of the object.(provides no additional information)ExampleObject that requires only two-viewIdentical view exists.Example 1The 3rd view has no significant contours of the object.(provides no additional information)Object that requires only two-viewIdentical view exists.Example 2The 3rd view has no significant contours of the object.(provides no additional information)Class activity : View selection

213465Select a necessary view ?

Class activity : View selectionSelect a necessary view ?213465

Class activity : View selection213465Select a necessary view ?Projection systems1. First angle system2. Third angle system

FirstquadrantThirdquadrant- European countries- ISO standard- Canada, USA, Japan, ThailandTransparentplanesOpaqueplanes

1st angle system(Opaque planes)3rd angle system(transparent planes/glass box)Orthographic viewsFoldinglineFoldinglineFoldinglineFoldingline1st angle system3rd angle systemOrthographic views1st angle system3rd angle system

Front ViewFront ViewRight Side ViewRight Side ViewTop ViewTop ViewViews arrangementProjection symbols1st angle system3rd angle systemd1.7d2.2d1. Extension lines2. Dimension lines3. Leader lines4. Dimension numbers5. Local notesDimensioning components10274310 Drill, 2 HolesR1617NecessityAuxiliary view is needed when it is desirable to show the true size and shape of a surface that is not parallel toanyone of the principal planes of projection.

True size can not be observedfrom these principal views.Use of auxiliary viewIn practice, an auxiliary view is usually a partial viewshowing only the desired information.Example

ddddComplete viewPartial viewTypes of an auxiliary viewPrimary auxiliary views may be classified into 3 typesby their relative to the principal views.1. Adjacent to front view2. Adjacent to top view3. Adjacent to side viewWidth & Height&True lengthof edge viewWidth&DepthHeight&DepthAuxiliary view adjacent to front viewGlass box and revolutionView arrangementTrue sizeof an inclined plane

Example 1Do you remember?Depth dimension of the auxiliary viewcan be read from top view or side view.Auxiliaryplane

Hidden lines of the holesare omitted for clarity.StartReferencelineACDBPreferdistanceABCDExample 2Width&HeightHeight&DepthAuxiliary view adjacent to top viewGlass box and revolutionWidth & Depth&True lengthof edge viewTrue sizeof an inclined planeView arrangementWidth&HeightAuxiliary view adjacent to side viewGlass box and revolutionWidth&DepthTrue sizeof an inclined planeView arrangementHeight & Depth&True lengthof edge viewExample

ReferencelineStartPreferdistanceABCABC