First-Year Engineering Program

Engineering H191Engineering Fundamentals and Laboratory I

Week 02 Day 03

Isometric Pictorials

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Objectives

• Projections: The Four Basic Types (Review)• Creating Isometric sketches• Sketching Ellipses

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Projections: Four Basic Types

Orthographic Projections

Axonometric

Oblique Perspective

Pictorials

Note: Isometric is a special case of Axonometric

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Introduction to Isometric Projection

• Isometric means equal measure• All planes are equally or proportionately shortened and tilted• All the major axes (X, Y, Z) are 120 degrees apart

CUBE

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Making an Isometric Sketch

• Defining Axis

30o 30o

60o60o

Isometric Axis

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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

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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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Going From Isometric to Rectilinear

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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 Object: Add Side Face

Height

Depth

Side Face

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Blocking in the Object: Add Top Face

Top Face

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Adding Detail Cut Outs – Part 1

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Adding Detail Cut Outs – Part 2

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Adding Detail Cut Outs – Part 3

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Darken Final Lines - Part 4

Note: All visible edges will be darkened

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Draw the Isometric

• Use Isometric Grid Paper• Block is 6 x 3 x 3

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Isometric View

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Draw the Isometric

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Draw The Isometric

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Sketching a Circle

• Draw a square whose sides are the diameter of the circle.

• At the center of each side define the point of tangency for the circle.

• Draw the diagonals of the square.

• 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

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

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Step 3 – Ellipse on Back Face and Profile

Draw Tangent Lines for Profile

Complete 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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Summary

• Technical drawings are an effective communication media

• Projections of various types can be used

• Isometric projections and creating isometric sketches has been introduced

• Assignments will emphasize simple isometric sketches

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Review Questions

1. _______ sketches present the object in a single view, with all three dimensions represented

2. _______ sketches present the object in a series of projections, each one showing only two of the objects’ three dimensions

3. Which among the following is NOT an isometric axes (Hint: Use the Isometric Grid paper for reference)?

a) b) d)c)120°

120°120°

60° 60°

240°

60°90°

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• Follow Sketching and Text conventions from the reading assignment

• Refer to reading assignment to clarify questions

• Title Information is required. Avoid labels on the sketch.

• 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– Non-visible 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.

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In Class Assignment

• TG 2.23, 2.30, 2.36, & 2.40 in course packet

– Use Isometric Sketch Paper (ISP)

– Dwg 8

• Example from Inventor Ch 3

– Dwg 9