1 Introduction to Projections Four Basic Types Orthographic Projections Axonometric...

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Transcript of 1 Introduction to Projections Four Basic Types Orthographic Projections Axonometric...
1
Introduction to ProjectionsFour Basic Types
Orthographic
ProjectionsAxonometric
Oblique
Perspective
Pictorials
Note: An Isometric is special case of an Axonometric
2
Introduction to Isometric Projection
• The term Isometric literally means equal measure• All planes are equally or proportionately shortened and tilted• All the major axes (X, Y, Z) are 120 degrees apart
CUBE
3
Making an Isometric Sketch
• Defining Axis
30o 30o
60o60o
Isometric Axis
4
DepthWidth
Height
Isometric Axis Convention
Making an Isometric Sketch
• Axis Convention
Front view
Choose the longest dimension to be the width (or the depth) for optical
stability
5
WidthDepth
Height
Isometric Axis Convention
Making an Isometric Sketch
• Axis Convention
Front view
Choose the longest dimension to be the width or
the depth for optical stability
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Usage of the Grid Paper
Correct orientation Incorrect orientation
Note the alignment of the axes
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The Transformation BetweenThe Isometric Grid & Rectilinear Grid
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Object for Practice
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Blocking in the ObjectBegin with Front Face
Front Face
Height
Width
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Blocking in the ObjectAdd Side Face
Height
Depth
Side Face
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Blocking in the ObjectAdd Top Face
Top Face
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Adding DetailCut Outs – Part 1
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Adding DetailCut Outs – Part 2
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Adding DetailCut Outs – Part 3
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Darken Final LinesPart 4
Note: All visible edges will be darkened
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Sketching a Circle1. Draw a square whose
sides are the diameter of the circle.
2. At the center of each side define the point of tangency for the circle.
3. Draw the diagonals of
the square. 4. Orient the paper so you
can draw equal arcs to construct the circle
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Isometric ellipses
• In an isometric drawing, the object is viewed at an angle, which makes circles appear as ellipses.
• Holes
• Cylinders
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Ellipses Can be in Any of Three Planes
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Sketching an Isometric of a Hollow Pipe
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Step 1  Creating the Base Box
Diameter
Diameter
Length
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Step 2 – Ellipse on Front Face(Reference Technical Graphics, Section 4.2.7)
Lines to Tangent Points
 Lines to tangent points Corner to corner to get center
Tangent Points
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Step 3 – Ellipse on Front Face
Tangent Points
Sketch in Arcs
23
Step 3 – Ellipse on Back Face and Profile
Draw Tangent Lines for ProfileComplete Visible Part of Back Ellipse
Repeat for ellipse on rear face
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Step 4 – Ellipse for Hole on Front Face
Create Box for Hole
Sketch Ellipse
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Isometric of Hollow Pipe
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• Title Information is required. Avoid labels on the sketch.
• Title block on bottom with your name
• Leave the construction lines – MUCH lighter and thinner than the finished lines
• Include centerlines on isometrics
Tips for Drawing Assignments
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• Do not try to shade drawing – this is not a pencil sketching class.
• Use grid paper. Try to sketch along grid lines. Practice sketching straight lines and curves on a grid sheet.
Tips for Drawing Assignments
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Tips for Pictorial Views• In pictorial views, hidden lines are not
shown unless absolutely required for clarity• Nonvisible bottom of a blind hole• Important feature of object not in direct view
• In pictorial views, holes or notches without bottom/end visible should be assumed to go completely through the object.
• Centerlines are to be shown on all isometric pictorials.