1 Technical Communications. 2 Objectives Understanding graphics as a communication tool Technical sketching Projections –Orthographic –Pictorial Sketching.

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Technical Communications

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Objectives

• Understanding graphics as a communication tool• Technical sketching• Projections

– Orthographic– Pictorial

• Sketching hints• Lettering

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How Would You Describe This?

• In teams of two, describe using only words• How effective is this approach?

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• Freehand sketches

• Instrument drawings

• Computer drawings and models

Three Basic Types of Technical Drawings

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Introduction to Projections

• Present 3-D objects with 2-D media• Two Basic Categories

Orthographic Pictorial

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Projections: Four Basic Types

Orthographic Projections

Axonometric

Oblique Perspective

Pictorials

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Orthographic Projections

• Collection of 2D drawings• Accurately represent object

• Technical Graphics

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Orthographic Projection

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Defining the SixPrincipal Views

orOrthographic Views

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Which Views to Present?

• General Guidelines

– Pick a Front View that is most descriptive of object

– Normally the longest dimension is chosen as the width (or depth)

– Most common combination of views is to use: Front, Top, and Side View

– Views other than the Principal Views are called Auxiliary Views

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Conventional Orthographic Views

Height

Depth

Width

Front View

Top View

Right Side View

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• Hidden Lines – represent features that cannot be seen in the current view

• Centerlines – represent symmetry and mark the center of circles, the axes of cylinders, and the axes of symmetrical parts, such as bolts

Hidden and Center Lines in Orthographic Projections

• Object Lines – represent visible features for an object

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For Example:

1. Visible

2. Hidden3. Center

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• Front View• Right Side

View• Top View

Creating the Orthographic Projection Sketch

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Step 1 – Lightly Block Three Views

Use very light lines for drawing in

the construction

lines

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Step 2 – Lightly Block Major Features

Use very light lines for

drawing in the construction

lines

• Holes• Arcs• Cutouts

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Step 3 – Refine and Locate Features in All Views

Use very light lines for drawing in

the construction

lines

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Step 4 – Add Final Lines

Use very light lines for drawing in

the construction

lines

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Completed Sketch

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Add Another View

• Sketch the left side view of the object• Compare your view with the others at your table

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Add Another View

• Does yours look something like this?

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Lettering Notes

• Lettering Guidelines – Technical Graphics: Chapter 1

• Lettering Styles– Shape of Letters– Order of drawing lines

• Character Uniformity• Spacing

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Lettering – Vertical Gothic Font

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Sketching Tips: General

• Relax and draw in a direction comfortable to you• Mark end points of the lines to be sketched and

draw between them• Draw long lines as a series of short ones• Use grid paper when available• Follow sketching and text conventions

• Do NOT use a straight edge to draw lines!

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Sketching Tips: Construction Lines

• Use construction lines• Begin by drawing bounding boxes with

construction lines• Make construction lines much lighter and thinner

than finished lines• Identify the major features and overall

dimensions• Leave construction lines on the sketch

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Sketching Tips: Miscellaneous

• Do not shade the drawing – this is not pencil sketching

• Title information is required• Keep views aligned (very important)• Include centerlines on isometrics• Avoid labels on the sketch• Draw neat circles – change page orientation if

needed

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Creating Production Drawings

Goals• Understand production drawings, including detail

drawings and assembly drawings

Reference• Technical Graphics

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Mechanical Production Drawings

• Production drawings (sometimes called Working drawings) are the complete set of drawings specifying the manufacture and assembly of a product.

• Generally consists of multiple drawings, on multiple sheets. A title block appears on each sheet.

• May contain written instructions called specifications.

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Set of Production Drawings

A set of Production Drawings has three main parts:

1. Detail drawings of each non-standard part, usually one part per "sheet".

2. An assembly drawing (or subassembly drawings) showing all parts in a single drawing.

3. A bill of materials (BOM). This is essentially a parts list.

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Reading Production Drawings

• Our first goal is to learn how to read a set of production or working drawings.

• Example: simple fingernail clipper

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Example 1 – Assembly Drawing

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Full Section View

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Detailed Part Drawing: Rivet

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Detailed Part Drawing: Bottom Clipper

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Assembly Drawing

37AU 2006

Example 2 – Butterfly Valve

Isometric

Half-sectionedisometric

Exploded

Individual Part Drawings