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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
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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
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
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
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
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
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
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