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1 Isometric ellipses In an isometric drawing, the object is viewed at an angle, which makes circles appear as ellipses. Holes Cylinders

Sketching Iso and Ellispses

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Isometric ellipsesIn an isometric drawing, the object is viewed at an angle, which makes circles appear as ellipses.

Holes

Cylinders

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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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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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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 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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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 Questions1. _______ sketches present the object in a single

view, with all three dimensions represented2. _______ 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.

• 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 ViewsIn pictorial views, hidden lines are not shown unless absolutely required for clarity, such as; Non-visible bottom of a blind hole Important feature of object not in direct

viewIn 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

Use Isometric Sketch Paper (ISP)