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Dept of M echanical Engineering and Mechanics, Drexel University

Sectional Orthographic Views

MEM 201

Fundamentals of Computer Aided Design

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Dept of M echanical Engineering and Mechanics, Drexel University

Todays Learning Objectives

Need for Sectional View

Contents of Sectional view

Identifying different kinds of sectional views.

Sectional View Guidelines and good practices.

Cross Hatching in AutoCAD.

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Dept of M echanical Engineering and Mechanics, Drexel University

Sectional Views

These are views that show internal features such

as cuts, holes, step cuts as orthographic views.

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Dept of M echanical Engineering and Mechanics, Drexel University

Sectional Views

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Dept of M echanical Engineering and Mechanics, Drexel University

Purpose of Sectional Drawings

Depict assembly of parts.

Show internal detail.

Replace complex orthographic views.

Describe materials in an assembly.

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Dept of M echanical Engineering and Mechanics, Drexel University

Contents of a Sectional View

Sectional views have: Cutting plane shown as edge view: cutting plane line. Cutting plane arrow representing the direction of line of sight. Section lines (hatch) shows where areas of solid material are

present.

AA

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Dept of M echanical Engineering and Mechanics, Drexel University

Different Kinds of Sectional Views

Full Section

Half Section Offset Section Aligned Section

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Dept of M echanical Engineering and Mechanics, Drexel University

Full Sectional View

Cutting plane cuts fully through object. No Hidden Lines are shown.

Visible Lines behind the cutting plane must be shown.

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Dept of M echanical Engineering and Mechanics, Drexel University

Half Sectional View

Cutting plane passes halfway through object. Used for symmetric parts. Omit hidden lines.

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Dept of M echanical Engineering and Mechanics, Drexel University

Offset Sectional View

Cutting plane line not straight but offset to passthrough important features.

Dont show cut formed by offset.

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Dept of M echanical Engineering and Mechanics, Drexel University

Aligned Sectional View

Align sections cut at an angle (for circular shapes).

Features may be projected onto plane for clarity.

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Dept of M echanical Engineering and Mechanics, Drexel University

Good Sectional View Drawing Practices

Different parts at different angles or patterns Hatch spacing of about 1/16-1/8

Cutting plane line .020 wide (bold) Section or hatch lines -- thin .007 Visible lines -- width .015

Do not show Hidden lines. Direction 45

not parallel or perpendicular to boundary Name them on the side.

Section A-A

AA

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Dept of M echanical Engineering and Mechanics, Drexel University

Position of Sectional Drawings

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Dept of M echanical Engineering and Mechanics, Drexel University

Sectioning of Holes

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Dept of M echanical Engineering and Mechanics, Drexel University

Cross Hatching in AutoCAD

AutoCAD can apply a given pattern to fill an area. The area must be a closed area. To fill the area use the BHATCH command.

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Dept of M echanical Engineering and Mechanics, Drexel University

In AutoCAD.

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Dept of M echanical Engineering and Mechanics, Drexel University

Standard Material Patterns

The ANSI patterns

represent the more standardengineering materials.

ANSI31 is the genericmaterial which can be usedin no material is specified.

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Dept of M echanical Engineering and Mechanics, Drexel University

Predefined Pattern Library

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Dept of M echanical Engineering and Mechanics, Drexel University

Questions

?

Note: A 20min quiz of Orthographic Views, SectionalViews will follow next week.