Chapter 7: Multiviews

1. Chapter 7: Multiviews Orthographic Projection is any projection of the feature of an object onto an imaginary plane. The line of sight is perpendicular to the plane of projection. Multiview Projection establishes views of an object upon 2 or more planes of projection by using orthographic projection techniques.

2. The result of a multiview projection is a multiview drawing. • Surfaces of the object are shown in true size & shape. • Used in mechanical drafting to dimension detail drawings. Multiview Drawings

3. Views: top, front, right, & left side, rear & bottom • Views are aligned. • The front view is the primary view. • There is always one dimension in common between adjacent views. • Third angle projection is the multiview setup used by the U.S.A. (First angle projection is used in Europe). Multiview View Setup

4. View Alignment

5. Represents the most natural position of use • Provides the best shape description & most characteristic contours • Has the longest dimension • Has the fewest hidden features • Is the most stable & natural position Front View Selection

6. Top, front & right side views usually can show all the features. • Objects can be described with only two views or just one view. • The importance of a view is to clearly show the contour of a surface. • Avoid hidden features. Basic question to always ask when selecting a view: “Can the part be easily manufactured without confusion from the drawing?” Other View Selection Considerations

7. Partial Views: Used when space is limited Used with symmetrical objects Partial views are sometimes confusing View Enlargements Used when part of a view is too detailed or too small to place dimensions on it The word VIEW is placed under the enlarged view Partial Views & View Enlargement

8. When the line of sight is perpendicular to a circular feature, the feature appears round. • When a circle is projected onto an inclined surface, its view is elliptical in shape. • A view of a hole is projected as a circle and its hidden view is shown through the part. Projection of Circles

9. When a curved surface from an inclined plane must be drawn in multiview, a series of points on the curve establishes the contour on the view. • Then the points are connected with an irregular curve. Arcs on Inclined Planes

10. Fillets are the rounded inside corners of a cast or forged part. • Ease of machining and extra material for stress relief • Allow patterns to release more easily from casting or forging • Size of the fillets depends on precision of casting method • Rounds are rounded outside corners • Used to relieve sharp exterior edges • Used for the same reasons as fillets in casting & forging Fillets and Rounds

11. Rounded Corners in Multiviews An outside or inside slightly rounded corner of an object is represented in a multiview as a single contour line.

12. Runout of features that intersect cylindrical shapes is projected from the point of tangency of the intersecting feature. • Rectangular-shaped features have a fillet at the runout. • Curved (elliptical/round) features contour toward the centerline of the runout. • Runouts also exist when a web intersects another feature. RunoutsThe intersection of features with circular objects are projected in multiview to the extent where one shape runs into the other.

13. Object lines take precedence over hidden lines and centerlines. • Hidden lines take precedence over centerlines. • Section cutting plane lines take precedence over centerlines. Line Precedence Sometimes one line will fall on top of another line in a multiview drawing - the drafter will choose the line that is precedent.

14. Third Angle ProjectionCommonly used in the U.S.A.

15. First Angle ProjectionCommonly used in Europe

16. Demonstrate the Following Procedures for Multiview Drawings Sketching the Layout Drawing the Layout