9 Multiview Drawings

Permission granted to reproduce for educational use only. © Goodheart-Willcox Co., Inc. Understand the principles of orthographic projection. Use orthographic projection to develop multiview drawings. Identify and explain projection planes and how they relate to multiview drawings. Determine the views necessary to completely describe an object in a multiview drawing.

Permission granted to reproduce for educational use only. © Goodheart-Willcox Co., Inc. Identify various types of features existing within objects. Identify and explain positive and negative mass as it relates to an object. Explain the difference between primary and secondary views of objects and features. Center a multiview drawing on the drawing sheet.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Multiview Drawings Same drafting principles are used whether making a mechanical drawing or CAD drawingmechanical drawing Principal views used to project necessary viewsPrincipal views

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Visualizing Objects Visualize 3D object in glass box –Think of six box surfaces as standard projection planes

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Orthographic Projection Primary tool used to project views in drafting Used to develop views for engineering working drawingsengineering working drawings

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Orthographic Projection Methods Third-angle projection –Used in United States First-angle projection –Used in most European countries All views are centered about and originate from front view

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Principal Planes

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Third-Angle Projection

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. First-Angle Projection

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Object Features Must be identified by drafter Solid portions of object represent positive mass Material removed represents negative mass –Some operations create features without removing material

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Primary and Secondary Views Features are represented in all views Primary view shows feature in true shape and sizePrimary view Secondary view typically shows the feature with hidden lines

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Primary and Secondary Views (Cont.)

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. True Faces and Foreshortening True face drawn when surface is parallel to projection planeTrue face –May be drawn full size or to scale Foreshortening occurs when surface is not parallel to projection plane –Applies for inclined surfaces –Surface drawn smaller than true size and shape

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Edges, Intersections, and Limiting Edges

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Selecting Views to Be Drawn Only draw views necessary to completely describe object Two to three views are usually sufficient Eliminate views showing identical shape description

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Selecting Views to Be Drawn (Cont.) Designate the view that shows the most visible features as the front view Determine the number of views needed based on content of front view Draw views showing the fewest features as hidden lines Place views in proper orthographic order

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Hidden Line Usage

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Projecting Views Each view shows minimum of two dimensions –Front view shows width and height –Top view shows width and depth –Side view shows height and depth Two adjacent views have one dimension in common

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Blocking In Used to create views Measure each distance once Double-check measurement for accuracy Project distance to adjacent view Do not “double-measure” distances Draw all projections as construction lines Darken lines to correct weights later

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Projecting Points Width measurements –Project between front and top views Height measurements –Project between front and side views Depth measurements –Project between top and side views –Use 45° projection angle or compass

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Transferring Depth Measurements

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Centering a Drawing with Construction Lines 1.Determine overall size of object and orientation. 2.Determine size of drawing area. 3.Allow 1″ between views. 4.Locate front view. Width of front view + depth of right view + 1″ = “X” Subtract “X” from overall drawing area width Divide difference by 2 Result is distance measured from left border for starting point of drawing

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Centering a Drawing with Construction Lines (Cont.) 5.Measure in from left border line using the calculated distance and draw a vertical construction line through this point. 6.From this line, measure over distance equal to width of front view and draw a vertical construction line. 7.Follow same procedure to center views vertically, using height of front view and depth of top view.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Centering a Drawing with Construction Lines (Cont.) 8.Measure up from lower border line using the calculated distance and draw a horizontal construction line through this point. 9.From this line, measure up height of front view and mark a point. Mark a point for spacing that separates views. Mark one more point for depth of top view. Draw construction lines through these points.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Centering a Drawing with Construction Lines (Cont.) 10.Project depth from top view to side view. 11.Draw in side view using construction lines. 12.Darken views to correct line styles and weights and erase remaining construction lines.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Centering a Drawing with a Centering Rectangle 1. Determine overall size of object and orientation. 2. Draw border and title block. 3. Locate center of drawing area with diagonals. 4. Lay out vertical and horizontal measurement lines. 5. Determine size of centering rectangle. 6. Center width of centering rectangle.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Centering a Drawing with a Centering Rectangle (Cont.) 7. Center height of centering rectangle. 8. Erase all construction lines except the lines for the centering rectangle. 9. Lay out the width, distance between views, and depth. 10. Lay out the overall height. 11. Lay out a 45  projection angle. 12. Draw a construction line to project the depth into the top view.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Centering a Drawing with a Centering Rectangle (Cont.) 13. Lay out features once and project. 14. Darken lines using correct weights.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Multiview Drawings in CAD CAD commands and projection methods similar to those in manual drafting are used for 2D views Points are projected using construction lines, coordinate entry, and drawing aids Some programs provide ability to create multiview drawings from 3D models –Common practice is to orient orthographic views of 3D drawing with pictorial view

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Multiview drawings use more than one two- dimensional view in order to accurately describe the _____ and _____ of the object being produced. shape, size

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Orthographic _____ is the process used to develop one-dimensional views of two- dimensional objects. projection

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. True or False? Third-angle projection is the projection technique typically used in the United States. True

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Name the three principal planes. Frontal plane, horizontal plane, and profile plane

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. The top view of an object is projected to the _____ plane. horizontal

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. The side view of an object is projected to the _____ plane. profile

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Object features are identified as _____ mass of the object. negative

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. When selecting the views necessary to completely describe an object, draw views that show the fewest _____ lines. hidden

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Explain the difference between primary and secondary views of features. The feature appears in its true shape and size in the primary view, and is usually represented with object lines. The secondary views usually represent the feature with hidden lines.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. What are two methods used to center drawings? Centering the drawing with construction lines and centering the drawing with a centering rectangle.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Engineering working drawings –Drawings used to manufacture or construct objects. First-angle projection –A method of orthographic projection in which views of an object are projected to the sides of an imaginary glass box and away from the viewer. Mechanical drawing –A drawing made with the aid of instruments.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Multiview drawing –A drawing that requires more than one two- dimensional view in order to provide an accurate shape and size description of the object being produced. Orthographic projection –A method of showing a three ‑ dimensional object in two dimensions by displaying various views. Primary view –In a multiview drawing, a view in which an object feature appears in its true shape and size.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Principal planes –In orthographic projection, the frontal, profile, and horizontal planes used to project views of an object. Principal views –The six basic views (front, top, right side, left side, rear, and bottom) used to develop three-dimensional objects in orthographic projection.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Third-angle projection –A method of orthographic projection in which views of an object are projected to the sides of an imaginary glass box and toward the viewer. True face –In orthographic projection, an object surface drawn in its true shape and size within a view.