2D Drawing Representation Chapter 5

Objectives Represent curved surfaces in multiview drawings Show intersections and tangencies of curved and planar surfaces Represent common types of holes Show fillets, rounds, and runout in a 2D drawing

Objectives (cont.) Use partial views Apply revolution conventions when necessary for clarity Draw removed views and projected views Show right and left hand parts

Objectives (cont.) Project curved surfaces by points Show and label an enlarged detail Show conventional breaks

Common Manufactured Features Certain features are part of many engineering designs Learning their names and shapes helps you visualize and communicate about them

Common Manufactured Features Fillet – a rounded interior blend between surfaces Round – a rounded exterior blend between surfaces Counterbore – a cylindrical recess around a hole, usually to receive a bolt head or nut

Common Manufactured Features Countersink – a conical-shaped recess around a hole, often used to receive a tapered screw head Spotface – a shallow recess like a counterbore used to provide a good bearing surface for a fastener Boss – a short raised protrusion above the surface of a part

Common Manufactured Features Lug – a flat or rounded tab protruding from a surface usually to provide a method for attachment Flange – a flattened collar or rim around a cylindrical part to allow for attachment Chamfer – an angled surface used on cylinders to make them easier to handle

Common Manufactured Features Neck – a small groove cut around the diameter of a cylinder, often where it changes diameter Keyway/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 won’t turn on it

Common Manufactured Features Knurl – a pattern form on a surface to provide for better gripping or more surface area for attachment Bushing – a hollow cylinder that is often used as a protective sleeve or guide or as a bearing

Common Manufactured Features

Conventional Representations Standard orthographic projections don’t always show complex shapes as clearly and simply as you may wish Simplified conventional representations that deviate from true orthographic projection may be used to enhance economy and clarity in a drawing

Intersections and Tangencies A plane surface can intersect or be tangent to a contoured surface When a plane intersects a contoured surface, a line is drawn to represent that edge When a plane surface is tangent to a contoured surface, no line or a thin phantom line is drawn

Intersections and Tangencies

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

Removed Views

Intersections and Tangencies Where a curved surface is tangent to a plane surface, no line is drawn When a curved surface intersects a plane surface, an edge is formed

Intersections and Tangencies

Intersections of Cylinders

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

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

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

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

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

Alignment of Views Always 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 Views A 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 view Removed views show features of an object more clearly Be sure to label removed views and provide a scale if necessary

Removed Views

Right-hand & Left-hand Parts Often parts function in pairs of similar opposite parts The two parts are mirror images and are not interchangeable Ordinarily, you draw only one of two opposite parts and label them appropriately

Right-hand & Left-hand Parts

Revolution Conventions Regular multiview projections are sometimes awkward, confusing, or misleading To 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