Chapter 05

2D Drawing RepresentationChapter 5

*Technical Drawing 13th EditionGiesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart 2009 Pearson Education, Upper Saddle River, NJ 07458.All Rights Reserved.

ObjectivesRepresent curved surfaces in multiview drawingsShow intersections and tangencies of curved and planar surfacesRepresent common types of holesShow fillets, rounds, and runout in a 2D drawing


Objectives (cont.)Use partial viewsApply revolution conventions when necessary for clarityDraw removed views and projected viewsShow right and left hand parts


Objectives (cont.)Project curved surfaces by pointsShow and label an enlarged detailShow conventional breaks


Common Manufactured FeaturesCertain features are part of many engineering designsLearning their names and shapes helps you visualize and communicate about them


Common Manufactured FeaturesFillet a rounded interior blend between surfacesRound a rounded exterior blend between surfacesCounterbore a cylindrical recess around a hole, usually to receive a bolt head or nut


Common Manufactured FeaturesCountersink a conical-shaped recess around a hole, often used to receive a tapered screw headSpotface a shallow recess like a counterbore used to provide a good bearing surface for a fastenerBoss a short raised protrusion above the surface of a part


Common Manufactured FeaturesLug a flat or rounded tab protruding from a surface usually to provide a method for attachmentFlange a flattened collar or rim around a cylindrical part to allow for attachmentChamfer an angled surface used on cylinders to make them easier to handle


Common Manufactured FeaturesNeck a small groove cut around the diameter of a cylinder, often where it changes diameterKeyway/Keyseat a shaped depression cut along the axis of a cylinder or hub to receive a key, used to attach parts to a cylinder so they wont turn on it


Common Manufactured FeaturesKnurl a pattern form on a surface to provide for better gripping or more surface area for attachmentBushing a hollow cylinder that is often used as a protective sleeve or guide or as a bearing


Common Manufactured Features


Conventional RepresentationsStandard orthographic projections dont always show complex shapes as clearly and simply as you may wishSimplified conventional representations that deviate from true orthographic projection may be used to enhance economy and clarity in a drawing


Intersections and TangenciesA plane surface can intersect or be tangent to a contoured surfaceWhen a plane intersects a contoured surface, a line is drawn to represent that edgeWhen a plane surface is tangent to a contoured surface, no line or a thin phantom line is drawn


Intersections and Tangencies


Removed ViewsIt is not always possible to show all of the drawing views in alignment on a sheetWhen this is the case, a removed view can be used and is indicated by:A viewing indicator arrow showing direction of sight orA viewing plane line


Removed Views


Intersections and TangenciesWhere a curved surface is tangent to a plane surface, no line is drawnWhen a curved surface intersects a plane surface, an edge is formed


Intersections and Tangencies


Intersections of Cylinders


RunoutsSmall curves called runouts are used to represent fillets that connect with plane surfaces tangent to cylinders


Conventional EdgesBecause the true projection may be misleading, there is a conventional way of showing rounded and filleted edges for the sake of clarity


Partial ViewsA view may not need to be complete in order to clearly describe an objectIf the view is symmetrical, you can draw a half-view on one side of the centerline


Showing Enlarged DetailsEnlarged views may be added that show details at a larger scale


Conventional BreaksTo shorten the view of a long object, you can use break lines


Alignment of ViewsAlways draw views in a standard arrangement to be sure that the drawings are not misinterpreted The front view should show the shape of the object clearly


Removed ViewsA removed view is a complete or partial view removed to another place on the sheet so it is no longer in direct projection with any other viewRemoved views show features of an object more clearlyBe sure to label removed views and provide a scale if necessary


Removed Views


Right-hand & Left-hand PartsOften parts function in pairs of similar opposite partsThe two parts are mirror images and are not interchangeableOrdinarily, you draw only one of two opposite parts and label them appropriately


Right-hand & Left-hand Parts


Revolution ConventionsRegular multiview projections are sometimes awkward, confusing, or misleadingTo prevent confusion, features may be revolved to line up vertically and project true length to make symmetry clear


Revolution Conventions


Common Hole Features


Common Features

Chapter 05

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