2OBJECTIVES 1. Represent curved surfaces in multiview drawings 2. Show intersections and tangencies of curved and planar surfaces3. Represent common types of holes4. Show fillets, rounds, and runouts in a 2D drawing5. Use partial views6. Apply revolution conventions when necessary for clarity7. Draw removed views and projected views8. Show right- and left-hand parts9. Project curved surfaces by points10. Show and label an enlarged detail11. Show conventional breaks
3Common Manufactured Features FilletRoundCounterboreCountersinkSpotfaceBossLugFlangeChamferNeckKeyway/KeyseatKnurlBushing
5VISUALIZING AND DRAWING COMPLEX CYLINDRICAL SHAPES Steps
6CYLINDERS WHEN SLICEDCylinders are often machined to form plane or other types of surfaces.Normal surfaces appear true shape in the view where the line of sight is perpendicular to the surface. In the two other views that normal surface appears on edge. The back half remains unchanged.
7CYLINDERS AND ELLIPSES If a cylinder is cut by an inclined plane, the inclined surface is bounded by an ellipse. This ellipse will appear as a circle in the top view, as a straight line in the front view, and as an ellipse in the side view.When a circular shape is shown inclined in another view and projected into the adjacent view it will appear as an ellipse, even though the shape is a circle.
8INTERSECTIONS AND TANGENCIES Where a curved surface is tangent to a plane surface no line is drawn, but when it intersects a plane surface, a definite edge is formed.When plane surfaces join a contoured surface, a line is shown if they are tangent, but not shown if they intersect.
9Intersections of Cylinders When the intersection is small, its curved shape is not plotted accurately because it adds little to the sketch or drawing for the time it takes. Instead it is shown as astraight line.When the intersection is larger, it can be approximated by drawing an arc with the radius the same as that of the large cylinder.
10FILLETS AND ROUNDSA rounded interior corner is called a fillet. A rounded exterior corner is called a round.Rounds on a CAD Model of a Design for a Three-Hole PunchFillets on a CAD Model.(Courtesy of Douglas Wintin.)(Courtesy of Ross Traeholt.)
11RUNOUTSSmall curves called runouts are used to represent fillets that connect with plane surfaces tangent to cylinders.Runouts from different filleted intersections will appear different owing to the shapes of the horizontal intersectingmembers.
12CONVENTIONAL EDGESThere is a conventional way of showing rounded and filleted edges for the sake of clarity. Added lines depicting rounded and filleted edges.Rounded and filleted intersections eliminate sharp edges and can make it difficult to present the shape clearly.
13NECESSARY VIEWS What are the absolute minimum views required to completely define an object?One-View DrawingTwo-View DrawingThree-View Drawing
14PARTIAL VIEWS You can use a break line to limit the partial view… A view may not need to be complete but needs to show what is necessary to clearly describe the object. This is called a partial view and is used to save sketchingtime and make the drawing less confusing to read.ORYou can use a break line to limit the partial view…
15Showing Enlarged Details When adding a detail, draw a circlearound the features that will be included in the detailPlace the detail view on the sheet as you would a removed view. Label successive details with the word DETAIL followed by a letter, as in DETAILA, DETAIL B,
16Conventional BreaksTo shorten the view of a long object, you can use break lines…Using a break to leave out a portion of the part, but allows the scale for the endsto be increased to show the details clearly.
17ALIGNMENT OF VIEWS Always draw views in the “standard” arrangement... Because CAD makes it easy to move whole views, it istempting to place views where they fit on the screen orplotted sheet and not in the standard arrangement. This is not acceptable.3D CAD software that generates 2D drawing views asprojections of the 3D object usually has a setting to select from third-angle or first-angle projection. Check your software if you are unsure which projection methods are available.
18REMOVED VIEWSA removed view is a complete or partial view removed to another place on the sheet so that it is no longer in direct projection with any other view.Removed View Using View Indicator ArrowRemoved View Using Viewing-Plane Line
19RIGHT-HAND AND LEFT-HAND PARTS Often, parts function in pairs of similar opposite parts, but oppositeparts can rarely be exactly alike.On sketches and drawings a left-hand part is noted as LH, and a right-hand part as RH.
20REVOLUTION CONVENTIONS Regular multiview projections are sometimes awkward, confusing, or actually misleading.Revolutions like these are frequently used in connection with sectioning. Revolved sectional views are called aligned sections.
21Common Hole Features Shown in Orthographic Views