Engineering Drawing from First Principles Using AutoCAD

Engineering Drawing from First Principles Using AutoCAD
Dennis Maguire
CEng, MIMechE, MemASME, REng. Des, MIED
City and Guilds International Chief Examiner in Engineering Drawing
Chapter!
First steps
By the end of this chapter, I hope you will be able to understand the following commands
and perform these activities:
• Open the drawing software program. Click and browse through each of the options on
the menu bar in turn and note that many sophisticated and advanced features are
available.
• Reposition the movable toolbox.
• Note standard drawing sizes.
• Appreciate Portrait and Landscape orientation of the drawing.
• Select and position an A4 size drawing sheet.
• Set Snap and Grid values.
• Draw lines between given coordinates.
• Operate the ZOOM command.
• Become familiar with the ORTHO button facility.
• Experiment with ERASE and BREAI( commands.
• Use the REDRAW command to clean up the screen.
• Draw circles and arcs.
• Use the RUNNING OBJECT SNAP OPTION to draw tangents and position tangency
points.
• Gain experience with the FILLET feature.
• Convert lines and arcs to polylines for finished outlines.
• Experiment with the TEXT command. Set text types and sizes.
• Note the minimum height of drawing characters and text abbreviations.
• Experiment with the MOVE, COpy and ROTATE commands and learn how to reposition
detail.
• Experiment with the ARRAY command.
• Choose screen preferences.
• Select coloured layers for different parts of a drawing.
• Note recommended thicknesses for various types of linework.
• Check available printers. Save your drawings with suitable file names and add drawing numbers
Chapter 2
Geometrical
applications
This chapter introduces you to:
• Dimensioned tangency examples.
• Tangency points and intersecting arcs.
• Polar and Rectangular arrays.
• Ellipse construction and properties.
• Scale factors.
• Wire parts.
• Symmetrical layouts.
• Double lines and arcs.
• Wire springs.
• Setting out exact rotation angles using the Gear Wheel example.
• Gear Wheel terminology.
• UNDO, REDO, BREAI(, EXTEND and TRIM features.
• Loci.
• Archimedian Spiral.
• Cylindrical and conical helix.
Chapter 2
–
Geometrical
applications
This chapter introduces you to:
• Dimensioned tangency examples.
• Tangency points and intersecting arcs.
• Polar and Rectangular arrays.
• Ellipse construction and properties.
• Scale factors.
• Wire parts.
• Symmetrical layouts.
• Double lines and arcs.
• Wire springs.
• Setting out exact rotation angles using the Gear Wheel example.
• Gear Wheel terminology.
• UNDO, REDO, BREAI(, EXTEND and TRIM features.
• Loci.
• Archimedian Spiral.
• Cylindrical and conical helix.
Chapter ~
Pictorial projections
This chapter introduces the following topics:
• Isometric principles and planes.
• Oblique, Cavalier and Cabinet projections.
• Planometric projections.
• COpy and ROTATE features applied to animation.
Chapter ~
Text and dimensions
This chapter introduces you to:
• Text types and editing options.
• Special characters.
• Overscoring and underscoring.
• Dimensioning principles.
• Functional and Auxiliary dimensions.
• Toleranced dimensions.
• The selection of limits and fits from ISO tables with shaft and hole combinations.
• Combining characters to produce limits and fits for use on drawings.
Chapter 6
Three-dimensional projection exercises
Chapter 7
Pattern development
By the end of this chapter you will be able to draw patterns for various hollow objects and
make useful models to check dimensions, shape, appearance and the position of joins.
These practical exercises assist in the overall comprehension of three-dimensional forms.
Applications of this type of work are found in thin sheet metal and plastics fabrications.
Development exercises include:
• Parts of rectangular and triangular prisms.
• Cylinders with branches.
• Cones and intersections.
• Hexagonal pyramid developments.
• True length applications
Chapter 8
Fastenings
This chapter introduces commonly used fastenings which are necessary for assembly
drawings. It is possible with CAD to store frequently used details in your own data bank,
then recall and reposition items, as required.
At the end of the chapter you will be able to draw accurately:
• Nuts, bolts, studs and washers from standard dimensions.
• Understand the terminology and conventions relating to nuts and bolts.
• Draw fastenings on sectional views and assemblies.
• Draw isometric views of nuts and bolts.
Chapter 9
Blocks and technical
diagrams
Layouts and diagrams are generally individually prepared special purpose drawings
presented in a neat and simple style. If the diagram shows a flow of events then details
are arranged so that the sequence, if possible, takes place from left to right or from top to
bottom. Notes, dimensions and other references are positioned to avoid ambiguity.
Remember that the user may not proficient in that particular branch of technology.
At the end of this chapter you will be able to make a block containing information which
can be used in your current drawing or stored for later use elsewhere. Examples of typical
diagrams are given for:
• Pipework and heating layouts.
• Electrical schematic line diagrams.
• Electrical wiring diagram for construction purposes.
• Floor layout diagram for a social event.
• Model Hi-Fi Midi sequencer connections
Chapter ~
Technical drawings for
industry
Examples are given here of typical technical drawings and may be copied to demonstrate competence as a CAD draughtsman. The drawings are chosen to provide experience of applications of engineering standards, conventions, principles and practice and
include:
• Drawing sheet layouts with title blocks, parts lists and borders.
• Webs and fillets applied to castings.
• First and third angle alternative solutions.
• Assembly drawing from given details.
• Transferring information from one drawing to another.
• Sectional views
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