lecture 8a isometric and orthographic 2012

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GE121

Drawing and Sketching: Isometric and Orthographic

Projections

Lecture 8A

1GE 121 Engineering Design--2012

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Engineering Drawings vs. Sketching Engineering Drawings

Used as output of the design process to communicate the final design for production

Precise lines and arcs, detailed, and almost always to scale

Engineering SketchingUsed at conceptual stage of designFreehand, general shapes and sizes, often

just ballpark dimensions, not to a precise scale, but rather simply relative proportions

Shading is not used in engineering sketchesWe will be primarily sketching


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Orthographic Projections: Unfolding the ‘Glass Box’


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Orthographic Layout of ViewsStandard: Top, Front & Right Side


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Sketching - Oblique Representation


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Sketching - Isometric Representation


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Isometric to Orthographic

Orthographic Views are used extensively in engineering

Often, they must be produced from a 3D object or possibly an existing Isometric drawing or sketch


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Isometric to OrthographicHints for Orthographic Sketching

• Identify the major features and overall dimensions• Use clean, crisp strokes• Do not use straightedges or scales when sketching• Start by drawing bounding boxes and a miter line, using

construction lines• Align the views• Use light construction lines to locate vertices and edges• Only measure dimensions along primary axes• Map inclined and oblique faces between all three views• Follow the precedence of lines• Double check to make sure there are no missing hidden

or center lines• Darken all visible, hidden and center lines


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Iso to Ortho (cont.)

Block in the 3 views using overall width, height and depth

Front View first, then project height and width using construction lines

Make sure depth is the same on Top and Right Views


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Lightly block in major features in each view

Place circles in views where they look round

Begin darkening major features


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Construction lines can be used to project location or size of one feature to another view

A miter line can be used to project Depth dimensions


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Finish adding all final lines

Be sure to add all hidden and center lines

Darken all final lines


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Completed Sketch with construction lines erased.


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Orthographic to IsometricOrthographic

drawings are common in engineering. Visualizing or creating the Isometric View is a critical engineering skill


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Orthographic to Isometric (cont.)• Hints for Isometric Sketching

• Identify major features and overall dimensions• Use clean, crisp strokes• Do not use straightedges or scales when

sketching• Start by drawing the axes at the front bottom

corner• Then sketch a bounding box, using construction

lines• Only measure dimensions along the primary

axes• Do not directly transfer angles from a multiview

to a pictorial


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Orthographic to Isometric (cont.)• Hints for Isometric Sketching (cont.)

• Use light construction lines to locate vertices and edges

• Sketch faces roughly in this order:1. Normal faces on the perimeter of the

bounding box2. Normal faces in the interior of the bounding

box3. Inclined faces4. Oblique faces

• Darken all object lines


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Ortho to Iso (cont.)

Set up Isometric Axes using 1 vertical line and 2 lines at 30 degrees from horizontal

Estimate the overall width height and depth of the object, and sketch the edges of a block that would completely enclose the object


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Sketch the outline of the front face using lines parallel and equal in length to the two previous height and width edges


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Sketch the outlines of the top and side faces using the same basic procedure as used for the front face

Begin sketching start/end points of major features


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Begin darkening major features as they are developed

Locate start/end points of additional and smaller features


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Locate and sketch start/end points for non-isometric lines such as the angled surface

Sketch and darken the non-isometric features


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Completed Isometric Sketch with construction lines erased


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Activity

Sketch an object(s) indicated by your instructor, first in Isometric View, and then in the 3 Standard Orthographic Views (Front, Top and Right Side)

If you complete early, attempt the same with a different shape

(There are some 3-D objects available in 2C02)


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GE 121 Engineering Design--2012 24

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Reference Images


lecture 8a isometric and orthographic 2012

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