Orthographic Projection n n Ortho perpendicular The system

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Orthographic Projection n n Ortho -- perpendicular The system of drawing views of an

Orthographic Projection n n Ortho -- perpendicular The system of drawing views of an object by projecting points perpendicularly onto projection planes. ¨ Projection lines represent line of sight ¨ Line of sight perpendicular to projection plane n Multiviews ¨ two-dimensional views of an object projected upon two or more planes of projection using orthographic projection techniques.

Orthographic projection

Orthographic projection

Multiview drawing of an object

Multiview drawing of an object

Glass Box Model n. Place object in a glass box so the sides of

Glass Box Model n. Place object in a glass box so the sides of the glass box are parallel to major surfaces of the object. n. Faces of the glass box serve as planes of projection n. Cut glass box along edges and unfold to obtain multiviews n Third-Angle projection - used in the US: ¨ Top view directly above the front view ¨ Right-side view to the right of front view

Glass Box Unfolding

Glass Box Unfolding

Orthographic Views n Common projection planes (aka principal projection planes) ¨ frontal F front

Orthographic Views n Common projection planes (aka principal projection planes) ¨ frontal F front view ¨ horizontal H top view ¨ profile P right-side view Cut and open the glass box to get principal orthographic views n Other views: n ¨ bottom, rear, left-side

Dimensions necessary to define object: ¨ Height H -- FV & RV ¨ Width

Dimensions necessary to define object: ¨ Height H -- FV & RV ¨ Width -- TV & FV ¨ Depth -- TV & RV n Alignment of views ¨ align n corresponding dimensions Represent hidden edges by dashed lines

Three space dimensions

Three space dimensions

Alignment of views

Alignment of views

Selecting the Front View Represents the most natural position of use n Provides the

Selecting the Front View Represents the most natural position of use n Provides the best shape description or most characteristic contours n Has longest dimension n Has fewest hidden features n

Good orientation

Good orientation

Object suspended in a glass box, producing the six principal views

Object suspended in a glass box, producing the six principal views

Unfolding the glass box to produce a six-view drawing

Unfolding the glass box to produce a six-view drawing

Most descriptive views

Most descriptive views

Types of Lines n Object lines (visible lines) ¨ solid lines ¨ represent visible

Types of Lines n Object lines (visible lines) ¨ solid lines ¨ represent visible surfaces or edges of the object n Hidden lines ¨ dashed lines ¨ invisible edges of the object n Centerlines ¨ long-short ¨ used n dashes to show centers of circles and arcs Others: extension, dimension, phantom, section, cutting-plane

Hidden features

Hidden features

Tangent partial cylinder

Tangent partial cylinder

Nontangent partial cylinder

Nontangent partial cylinder

Line Precedence n When one type of line falls in line with a different

Line Precedence n When one type of line falls in line with a different line type, draw the line that is most important based on precedence: ¨ Object lines take precedence over hidden lines and centerlines. ¨ Hidden lines take precedence over centerlines. ¨ In sectioning, cutting plane lines take precedence over center lines.

Representing Planes n Normal Plane ¨ parallel to a principal projection plane ¨ can

Representing Planes n Normal Plane ¨ parallel to a principal projection plane ¨ can be seen in only one view as True Size n Inclined Plane ¨ tilted with respect to two principal proj planes ¨ seen in two views; not true size n Oblique Plane ¨ tilted with respect to all principal proj planes ¨ seen in three views; not true size

Fundamental views of surfaces

Fundamental views of surfaces

Rule of configuration of planes

Rule of configuration of planes

Surface labeling

Surface labeling

Numbering the isometric pictorial and the multiviews to help visualize an object

Numbering the isometric pictorial and the multiviews to help visualize an object

Orthographic Views in Auto. CAD n Group entities together into LAYERS. Use the layer

Orthographic Views in Auto. CAD n Group entities together into LAYERS. Use the layer manager to create layers. ¨ Object lines ¨ hidden lines ¨ section lines and hatching ¨ text and dimensions ¨ title border n Create rectangles for front, top, and right-side views ¨ use 3 rd angle projection ¨ appropriate spacing between views

OV with Auto. CAD n n Use horizontal construction lines to locate height dimensions

OV with Auto. CAD n n Use horizontal construction lines to locate height dimensions common between FV and RV. Use vertical construction lines for width dimensions in FV and TV. Use a 45 -degree projection line (miter line) to transfer depth dimensions between TV and RV. Locate and plot projections of normal planes first, then inclined and oblique planes. Use solid lines for all visible object lines.

OV with Auto. CAD n n n Locate all hidden edges; use dashed lines.

OV with Auto. CAD n n n Locate all hidden edges; use dashed lines. Locate centerlines of all circles and arcs. Check visibility of lines following precedence rules. Add dimensions and text. Import title block.