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Section 1 Introduction to Drafting

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2 Section 1 Introduction to Drafting
Chapter 2 Traditional Drafting Equipment and Drawing Techniques Section 1 Introduction to Drafting

3 Objectives Identify and describe how to use basic drafting tools.
List and explain the types of lines in the Alphabet of Lines. Describe how to make drawings to scale. Use drafting tools and basic drawing techniques to make drawings. © Goodheart-Willcox Co., Inc.

4 Instrument Drafting Refers to manual (traditional) drafting.
Same principles used in CAD. Involves mechanical drafting equipment. (Koh-I-Noor Rapidograph, Inc.) © Goodheart-Willcox Co., Inc.

5 Drafting Equipment Compass Dividers Lead holder Box of leads
Technical pen Drawing board or table T-square Triangles (30°-60° and 45°) Scales Protractor Irregular curve Ellipse templates Erasers Drawing media Drafting tape Drawing pencils Pencil pointer © Goodheart-Willcox Co., Inc.

6 Drawing Boards Typically made from pine or basswood.
Available in standard sizes. Model may include parallel straightedge. © Goodheart-Willcox Co., Inc.

7 T-Square Made from wood, metal, or plastic.
Positioned against one end of drawing board. Used to draw horizontal lines. Provides edge for triangles. © Goodheart-Willcox Co., Inc.

8 Triangles Used to draw vertical and inclined lines.
Made of transparent plastic. © Goodheart-Willcox Co., Inc.

9 Drafting Machine Combines functions of several tools. T-square
Straightedge Triangles Protractor Scales (Vemco Corporation) © Goodheart-Willcox Co., Inc.

10 Drafting Media Vary by strength, translucency, and cost.
Opaque drawing sheets Tracing paper Vellum Polyester film © Goodheart-Willcox Co., Inc.

11 Vellum Strong, durable, and transparent.
Available in white or blue tint. Provides erasability without ghosting. More commonly used than tracing paper despite cost. © Goodheart-Willcox Co., Inc.

12 Drawing Sheet Sizes © Goodheart-Willcox Co., Inc.

13 Drawing Pencils Available in a variety of types.
Standard wooden pencils Rectangular leads Mechanical lead holders Thin leads © Goodheart-Willcox Co., Inc.

14 Drawing Pencils (Cont.)
Leads graded by hardness. Softer grades produce more opacity but may smudge drawing. Harder grades best for drawing sharp lines. © Goodheart-Willcox Co., Inc.

15 Sharpening the Pencil Use knife or drafter’s pencil sharpener.
Remove wood to expose 3/8" of lead. Pointing shapes the point desired. Conical points made for general work. Wedge points made for long, straight lines. © Goodheart-Willcox Co., Inc.

16 Alphabet of Lines Lines drawn thick or thin.
Thick lines drawn twice as thick as thin lines. Each line conveys specific meaning. © Goodheart-Willcox Co., Inc.

17 Alphabet of Lines (Cont.)
(American Society of Mechanical Engineers) © Goodheart-Willcox Co., Inc.

18 Alphabet of Lines (Cont.)
(American Society of Mechanical Engineers) © Goodheart-Willcox Co., Inc.

19 Line Conventions ASME standards observed.
(American Society of Mechanical Engineers) © Goodheart-Willcox Co., Inc.

20 Object Lines Also known as visible lines.
Used to represent visible features. Drawn thick. Should contrast noticeably with other lines. © Goodheart-Willcox Co., Inc.

21 Hidden Lines Used to represent features concealed to the observer.
Drawn thin. Made up of short, evenly spaced dashes. Should be omitted whenever clarity dictates. © Goodheart-Willcox Co., Inc.

22 Hidden Line Conventions
A—No gap shown between first dash and edge. B—Gap shown when first dash continues object line. C—Gap shown at nonintersecting line crossings. © Goodheart-Willcox Co., Inc.

23 Hidden Line Conventions (Cont.)
D—Dashes joined at corners. E—Arcs have dashes starting at tangent points. © Goodheart-Willcox Co., Inc.

24 Section Lines Used to show features sectioned by cutting plane.
Drawn thin. Typically drawn at 45°. Angle varied for sectioning multiple objects. Spacing kept uniform. © Goodheart-Willcox Co., Inc.

25 Section Lines (Cont.) May be used to indicate material of part.
General section lining also used for cast iron. © Goodheart-Willcox Co., Inc.

26 Centerlines Used to show center axes of objects.
Made up of alternating long and short dashes. Drawn thin. Should extend slightly past object lines. © Goodheart-Willcox Co., Inc.

27 Dimension Lines Used to indicate extents of dimensions.
Terminated by arrowheads and extension lines. Drawn thin. Leaders identify notes and annotated items. © Goodheart-Willcox Co., Inc.

28 Cutting-Plane Lines Used to represent cutting plane edge.
Composed of alternating long and short dashes. May consist of series of equal dashes. Drawn thick. Ends terminated by arrowheads to indicate viewing direction. © Goodheart-Willcox Co., Inc.

29 Break Lines Used to identify partial section views.
Drawn thick and freehand for short breaks. Drawn thin and dashed for long breaks. © Goodheart-Willcox Co., Inc.

30 Phantom Lines Used to identify object positions and details.
Made up of alternating long and short dashes. Drawn thin. © Goodheart-Willcox Co., Inc.

31 Datum Dimensions Used to identify datums. Drawn thin.
Employ same conventions for other dimensioning lines. © Goodheart-Willcox Co., Inc.

32 Construction Lines Used for drawing layout.
Made light enough to not reproduce on prints. Drawn thin. © Goodheart-Willcox Co., Inc.

33 Border Lines Used to “frame” drawing. Heaviest of all lines.
Not part of ASME standard. © Goodheart-Willcox Co., Inc.

34 Erasing Procedure The following steps apply when using soft vinyl eraser. Holding paper, rub lightly over error. For heavy erasing, use triangle for backing. Protect nearby lines with erasing shield. Make erasures before drawing final lines. Remove dust with brush or cloth. Inspect both sides of sheet for stray dirt. © Goodheart-Willcox Co., Inc.

35 Electric Erasers Used for extensive drawing revisions.
Equipped with soft rubber or vinyl erasers. Light pressure applied when erasing. © Goodheart-Willcox Co., Inc.

36 Neatness in Drafting Follow simple guidelines to keep drawings clean.
Keep hands and instruments clean. Use layout lines and “heavy-in” final lines. Brush away dust frequently while drawing. Lift tools from sheet when moving. © Goodheart-Willcox Co., Inc.

37 Neatness in Drafting (Cont.)
Keep drawing area clean and orderly. When lettering, protect completed areas with overlays. Keep drawings covered or in drawer when not working. Store finished drawings in portfolio. © Goodheart-Willcox Co., Inc.

38 Scale Used to lay off measurements. Made flat or triangular.
Triangular scales have multiple faces with different scales. © Goodheart-Willcox Co., Inc.

39 Types of Scales Classified as open-divided scales and full-divided scales. Architect’s scale Civil engineer’s scale Mechanical engineer’s scale Combination scale Metric scale © Goodheart-Willcox Co., Inc.

40 Architect’s Scale Used for architectural and structural drafting.
Divided into feet and inches. Triangular instruments include 11 different scales. © Goodheart-Willcox Co., Inc.

41 Civil Engineer’s Scale
Also called decimal scale. Used in civil engineering and manufacturing. Divided into units representing decimal parts of inch. Divisions may represent any measuring unit. © Goodheart-Willcox Co., Inc.

42 Mechanical Engineer’s Scale
Used for drawing machine parts. Used for measuring in inches or fractional inches. Also called “size” scales. © Goodheart-Willcox Co., Inc.

43 Common Drafting Scales
© Goodheart-Willcox Co., Inc.

44 Metric Scales Referred to as “size” scales.
Commonly referenced on drawings as ratios. Scale divisions based on number 10. © Goodheart-Willcox Co., Inc.

45 Drawing to Scale Objects drawn at reduced scale, enlarged scale, or at full size. © Goodheart-Willcox Co., Inc.

46 Reading the Architect’s Scale
Begin by reading main units in open-divided section. Read subdivided units in full-divided section. © Goodheart-Willcox Co., Inc.

47 Reading the Mechanical Engineer’s Scale
Begin by reading main units in open-divided section. Read subdivided units in full-divided section. © Goodheart-Willcox Co., Inc.

48 Reading the Civil Engineer’s Scale
Begin by reading number of whole units. Read subdivided units. © Goodheart-Willcox Co., Inc.

49 Reading the Metric Scale
Begin by reading number of whole units. Read subdivided units. © Goodheart-Willcox Co., Inc.

50 Laying Off Measurements
Position scale face up and eye from above. Mark distances with short dashes. Never make direct readings with dividers or compass. © Goodheart-Willcox Co., Inc.

51 Sheet Format Typical sheet margins vary from 1/4 to 1/2.
Margins greater for sheets to be rolled. Drawing information included in title block. © Goodheart-Willcox Co., Inc.

52 Drawing Horizontal Lines
Draw along upper half of straightedge. Move pencil toward your drawing hand. Incline pencil and rotate to keep conical point. Work from top of sheet to bottom. © Goodheart-Willcox Co., Inc.

53 Drawing Vertical Lines
Hold triangle above straightedge. Draw upward. Incline pencil and rotate to keep point conical. Begin on side of sheet away from your drawing hand. © Goodheart-Willcox Co., Inc.

54 Drawing Inclined Lines
Place triangle above straightedge. Use correct triangle for given line. © Goodheart-Willcox Co., Inc.

55 Drawing Inclined Lines (Cont.)
Combine triangles for different drawing angles. Use protractor for angles not shown. © Goodheart-Willcox Co., Inc.

56 Drawing Parallel Inclined Lines
Align straightedge and triangle with given line. Two triangles can be used for lines at close distances. © Goodheart-Willcox Co., Inc.

57 Drawing a Perpendicular to an Inclined Line
Position triangle’s hypotenuse along straightedge. Adjust to align triangle with given line. Move triangle to desired location for perpendicular. © Goodheart-Willcox Co., Inc.

58 Drawing a Perpendicular to an Inclined Line (Cont.)
For longer lines, align triangle’s hypotenuse with given line. Revolve triangle so that hypotenuse is perpendicular to line. Move triangle to desired location for perpendicular. © Goodheart-Willcox Co., Inc.

59 Using a Protractor Insert Fig 2-45 © Goodheart-Willcox Co., Inc.

60 Compass Used for drawing circles and arcs. Bow compass
Friction-joint compass Beam compass © Goodheart-Willcox Co., Inc.

61 Bow Compass Small and large instruments available.
Includes adjusting screw. © Goodheart-Willcox Co., Inc.

62 Sharpening the Compass Lead
Insert Fig 2-52 © Goodheart-Willcox Co., Inc.

63 Drawing Arcs and Circles
Measure radius on scrap paper. Adjust compass setting. Draw lightly, then “heavy-in.” © Goodheart-Willcox Co., Inc.

64 Drafting Templates Used for drawing common symbols and shapes.
Made in standard unit sizes. Available for use with lettering equipment. © Goodheart-Willcox Co., Inc.

65 Using a Circle Template
Lay out centerlines. Align centerlines with template. Draw selected circle. © Goodheart-Willcox Co., Inc.

66 Dividers Used for transferring distances. Used to divide lines.
Set similar to compass. © Goodheart-Willcox Co., Inc.

67 Using Dividers © Goodheart-Willcox Co., Inc.

68 Using Dividers (Cont.) © Goodheart-Willcox Co., Inc.

69 Proportional Dividers
Used for dividing objects into equal parts. Used for laying off proportional measurements. Adjusted to set ratios between opposite legs. (Alvin & Co.) © Goodheart-Willcox Co., Inc.

70 Irregular Curve Also called French curve.
Used for drawing smooth curves. Made up of successive curves. © Goodheart-Willcox Co., Inc.

71 Drawing Irregular Curves
Insert Fig 2-63(2) © Goodheart-Willcox Co., Inc.

72 Drawing Irregular Curves (Cont.)
© Goodheart-Willcox Co., Inc.

73 Proper Instrument Techniques
Use light construction lines for all layout work. Erase unneeded lines prior to “heavying-in.” “Heavy-in” lines to proper weight. Keep drawing surface free of loose graphite. © Goodheart-Willcox Co., Inc.

74 Drawing Order for Finished Lines
Arcs and circles. Horizontal lines from top to bottom. Vertical lines from your non-drawing hand to your drawing hand. Inclined lines from top to bottom, starting from your non-drawing hand. © Goodheart-Willcox Co., Inc.

75 Inking Drawings Rarely done for working drawings.
Common for technical publications. Provides sharper line definition. Technical pen used rather than ruling pens. © Goodheart-Willcox Co., Inc.

76 Inking Procedure Lay out construction lines in pencil.
Ink arcs by joining each tangent point. Ink circles and ellipses. Complete irregular curves. Complete lines in order of line weight. Ink notes, dimensions, and title block. © Goodheart-Willcox Co., Inc.

77 Review Questions 1. Which instrument is used to draw inclined lines?
A. Compass B. Dividers C. Triangle D. Irregular curve C. Triangle © Goodheart-Willcox Co., Inc.

78 Review Questions 2. A _____ provides an edge against which other instruments are placed to draw vertical and inclined lines. A. T-square B. drawing board C. French curve D. Protractor A. T-square © Goodheart-Willcox Co., Inc.

79 Review Questions 3. Which of the following types of drafting media provides the most durability? A. Paper B. Tracing paper C. Vellum D. Polyester film D. Polyester film © Goodheart-Willcox Co., Inc.

80 Review Questions 4. _____ lines are used to represent features that are concealed from the observer. A. Hidden B. Object C. Extension D. Section A. Hidden © Goodheart-Willcox Co., Inc.

81 Review Questions 5. _____ lines are used to represent materials such as cast iron. A. Hidden B. Object C. Extension D. Section D. Section © Goodheart-Willcox Co., Inc.

82 Review Questions 6. _____ lines are thin lines used to show alternate positions and repeated details. Phantom © Goodheart-Willcox Co., Inc.

83 Review Questions 7. The _____ scale is most commonly used for drawing machine parts where dimensions are in decimal or fractional inches. mechanical engineer’s © Goodheart-Willcox Co., Inc.

84 Review Questions 8. Parallel lines can be drawn using a(n) _____ and a triangle. T-square © Goodheart-Willcox Co., Inc.

85 Review Questions 9. _____ are used to transfer distances and to divide lines into equal parts. Dividers © Goodheart-Willcox Co., Inc.

86 Review Questions 10.Which instrument is used to measure and mark off angles? A. Scale B. Protractor C. Dividers D. Irregular curve B. Protractor © Goodheart-Willcox Co., Inc.

87 Review Questions 11.Which of the following guidelines applies when making drawings? A. Lay out construction lines with thick lines. B. Use your non-drawing hand to remove erasure dust. C. Darken lines from the bottom of the sheet to the top. D. Incline the pencil in the direction lines are drawn. © Goodheart-Willcox Co., Inc.

88 Review Questions 12. _____ are “heavied-in” first when completing work. A. Horizontal lines B. Vertical lines C. Inclined lines D. Arcs and circles © Goodheart-Willcox Co., Inc.

89 Glossary Alphabet of Lines Architect’s scale
A standardized collection of the different types of lines used in drafting, providing conventions that describe how lines are drawn. Architect’s scale Scale most commonly used in making drawings for the building and structural industry. © Goodheart-Willcox Co., Inc.

90 Glossary Beam compass Border lines
Instrument used for drawing very large circles and arcs. Border lines Heavy lines used as a “frame” for the drawing. They are not part of the ASME standard. © Goodheart-Willcox Co., Inc.

91 Glossary Bow compass Break lines
Compass with a steel ring head and an adjusting screw. Break lines Lines used to indicate a section break in a partial view. Short breaks are indicated by a series of short, thick lines drawn freehand. Long breaks are indicated by lines with long, thin dashes. © Goodheart-Willcox Co., Inc.

92 Glossary Centerlines Civil engineer’s scale
Thin lines consisting of alternating long and short dashes, used to show centers of objects and paths of motion. Civil engineer’s scale A full-divided scale used in civil engineering where large reductions are required for drawings such as maps and charts. It is also widely used in manufacturing. © Goodheart-Willcox Co., Inc.

93 Glossary Combination scale Compass
A triangular scale combining selected scales from the architect’s scale, civil engineer’s scale, and mechanical engineer’s scale. Compass A manual drafting instrument used to draw circles and arcs. © Goodheart-Willcox Co., Inc.

94 Glossary Construction lines Cutting plane
Very light, gray lines used to lay out all work. Cutting plane An invisible plane passing through an object. © Goodheart-Willcox Co., Inc.

95 Glossary Cutting-plane lines Datum
Thick, dashed lines indicating the location of the edge view of a cutting plane for use with a section view. Datum A point, line, or surface assumed to be exact size and shape, and in an exact location for establishing the location of other features. © Goodheart-Willcox Co., Inc.

96 Glossary Dimension lines Dividers
Thin lines terminated by arrowheads, used to indicate the extent and direction of dimensions. Dividers A manual drafting instrument used to transfer distances and to divide lines into equal parts. © Goodheart-Willcox Co., Inc.

97 Glossary Drafting machine Drafting media
A manual instrument that combines the functions of the T-square, straightedge, triangles, protractor, and scales into one tool. Drafting media Materials used in the preparation of drawings or tracings. © Goodheart-Willcox Co., Inc.

98 Glossary Drafting templates Erasing shield
Manual drafting tools useful for drawing commonly used characters and symbols. Erasing shield Used to cover and protect details around an area being erased. © Goodheart-Willcox Co., Inc.

99 Glossary Extension lines French curve
Thin lines used to indicate the termination of a dimension. French curve A manual drafting instrument used for drawing smooth curves through plotted points. Also known as an irregular curve. © Goodheart-Willcox Co., Inc.

100 Glossary Friction-joint compass Full-divided scale
Compass that provides easy adjustment for drawing larger arcs or circles. Full-divided scale Scale that has all units along the entire scale subdivided. © Goodheart-Willcox Co., Inc.

101 Glossary Ghosting Hidden lines
A smudged area on a copy of a drawing caused by damage from erasing or mishandling. Hidden lines Lines that indicate edges, surfaces, and corners of an object that are concealed from the view of the observer. © Goodheart-Willcox Co., Inc.

102 Glossary Instrument drafting Irregular curve
The process of making technical drawings using instruments, templates, scales, and other mechanical equipment. Irregular curve A manual drafting instrument used for drawing smooth curves through plotted points. Also known as a French curve. © Goodheart-Willcox Co., Inc.

103 Glossary Leaders Mechanical engineer’s scale
Lines drawn to notes or identification symbols used on the drawing. Mechanical engineer’s scale Scale that is useful in drawing machine parts where the dimensions are in inches or fractional parts of an inch. © Goodheart-Willcox Co., Inc.

104 Glossary Metric scale Object lines
Scale used for work on metric drawings or dual-dimensioned drawings. Object lines Thick lines used to outline the visible edges or contours of an object that can be seen by an observer. Also known as visible lines. © Goodheart-Willcox Co., Inc.

105 Glossary Open-divided scale
Scale that has the main units numbered along the entire length of each scale. Only the first main unit is subdivided into fractional or decimal segments of the major unit. © Goodheart-Willcox Co., Inc.

106 Glossary Phantom lines Pointing
Lines consisting of alternating thin, long dashes and short dashes, used to show alternate positions, repeated details, or paths of motion. Pointing Finishing the point of a wooden pencil on a piece of scrap paper or by using a lead pointer, such as a sandpaper pad. © Goodheart-Willcox Co., Inc.

107 Glossary Polyester film Proportional dividers
Durable drafting media that provides dimensional stability, strong resistance to tearing, easy erasing, and high transparency. Proportional dividers Dividers used to divide linear and circular measurements into equal parts and to lay off measurements in a given proportion. © Goodheart-Willcox Co., Inc.

108 Glossary Protractor Scale
Manual drafting instrument used to measure and to mark off angles. Scale A measuring device with graduations for laying off distances. A scale is used to draw objects to full, reduced, or enlarged size. © Goodheart-Willcox Co., Inc.

109 Glossary Section lines Technical pen
Thin lines used to represent surfaces exposed by a section plane. Different line conventions are used for representing specific materials. Technical pen Inking instrument available in a series of point sizes. © Goodheart-Willcox Co., Inc.

110 Glossary Title block Tracing paper
Included on a drawing to provide pertinent information about the drawing and supplementary data. It is usually located in the lower-right corner. Tracing paper Translucent drawing paper. © Goodheart-Willcox Co., Inc.

111 Glossary Triangles T-square
Manual drafting instruments made of transparent plastic and used to draw vertical and inclined lines. T-square A manual drafting instrument that slides along one edge of the drafting board and is used to draw horizontal lines. It also provides an edge against which triangles are placed to draw vertical and inclined lines. © Goodheart-Willcox Co., Inc.

112 Glossary Vellum Drafting media made of 100% rag content and impregnated with a synthetic resin to provide high transparency. © Goodheart-Willcox Co., Inc.

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