Post on 19-Aug-2020
EDT 300/ENGR 306 1
SketchingSketching
Chapter 2Chapter 2
Sacramento City CollegeEDT 300/ENGR 306
2
Objectives Objectives
Describe the importance of freehandsketching for communicating technical ideas.
Letter clear, neat, freehand notes and directions on a technical drawing or sketch.
Communicate technical ideas through freehand sketching.
3
Objectives Objectives
Develop design ideas through multi-view or pictorial sketches.
4
Sketching and LetteringSketching and Lettering
Vocabularyarcsaxis (axes)compositionconcentric circlesellipsesGothic letteringguidelinesisometric linesisometric sketchletteringlinenonisometric lines
oblique sketchoverlayplanepointproportionradius (radii)tangent arcs texture
5
SketchingSketching
Sketches•
Sketches bring ideas to life.•
Sketches communicate thoughts which cannot be said.
•
Freehand sketching is the simplest form of drawing.
•
Sketching is a quick way to express ideas, •
A sketch can greatly simplify a technical discussion.
6
SketchingSketching
•
Professionals who use sketching•
Designers•
Drafters•
Technicians•
Engineers, and •
Architects
•
Sketching is used to explain complicated ideas or unclear thoughts.
7
The Language of SketchingThe Language of Sketching
Four Basic Visual Symbols Which Can Be Seen.•
A point – a symbol that describes a location in space.
•
A line – A path between two points.
•
A plane – two non parallel lines define a plane which is a flat surface.
•
A texture or surface quality.
8
The Language of SketchingThe Language of Sketching
•
Any idea, no matter how simple or complicated can be sketched using these four visual symbols.
9
Reasons For SketchingReasons For Sketching
We draw sketches 1. To persuade people who make decisions about a project that an idea is good.
2. To develop a proposed solution to a problem so that a client can respond to it.
10
Reasons For SketchingReasons For Sketching
We draw sketches3. To clarify a complicated detail of a drawing that has more than one view by enlarging it or by creating a simple pictorial (picture-like) sketch.
4. To give design ideas to drafters to that they can do the detail drawings.
11
Reasons For SketchingReasons For Sketching
We draw sketches 5. To develop a series of ideas for refining a new product or machine part.
6. To develop and analyze the best methods and materials for making a product.
12
Reasons For SketchingReasons For Sketching
We draw sketches7. To record permanently a design improvement on a project that already exists.
The change may result from a need to repair a part that breaks over and over again.
13
Reasons For Sketching (contReasons For Sketching (cont’’d)d)
We draw sketches8. To show that there are many ways to look at or solve a problem.
9. To spend less time in drawing.
It is much quicker to make a sketch, which takes only a pencil and an sheet of paper, than to create a mechanical drawing.
EDT 300/ENGR 306 14
Types of SketchesTypes of Sketches
15
Types of SketchesTypes of Sketches
Any image drawn on paper freehand may be called a sketch.
Most drafters use several types of sketches.
The type of sketch used depends upon the purpose and the lifespan required for the sketch.
16
Rough SketchesRough Sketches
Rough SketchesQuick and dirtyAre usually drawn quickly with jagged lines.
Primary purpose is to express thoughts quickly
Refer to Figure 2-21.
17
Rough SketchesRough Sketches
GuidelinesInstruments or straightedges are not usedto prepare a rough sketch.
Instruments tend to restrict the creative expressions developed with god pencil techniques.
Avoid mechanical hard-line look.
Concentrate on using good proportions.
18
Refined SketchesRefined Sketches
Refined SketchesAre drawn more carefully than rough sketches.
Show good proportion and excellent balance.
19
Refined SketchesRefined Sketches
Refined SketchesYou may use a straightedge to control long lines on a refined sketch.
However, never allow the line to look mechanically drawn.
Sketched lines should have some irregular character.
20
Presentation SketchesPresentation Sketches
Presentation SketchesPresentation sketches are pictorial sketches that have been greatly refined.
Are used to convince a client or management to accept and approve the ideas presented.
21
Presentation SketchesPresentation Sketches
Presentation SketchesPictorial sketches have a three-dimensional view that can be understood easily by non-technical people.
Generally drawn so that they look glamorous, artistic or eye-appealing.
22
Temporary and Permanent SketchesTemporary and Permanent Sketches
Sketches may be temporary or permanent.
Some are done just to solve an immediate problem.
Others are kept longer.
23
The OverlayThe Overlay
A good way to refine a sketch is to use overlay paper.
Overlay is a piece of translucent tracing paper that is placed on top of a sketch or drawing.
Because you can see through the paper, you can quickly trace the best parts of the sketch or drawing underneath.
24
The OverlayThe Overlay
Overlay is used in three important ways:
1. Reshaping a design (Fig 2-22).
2. Used to refine the drawing itself without really changing its shape entirely.
3. Can be used to add various options to a basic drawing.
25
26
27
Views Needed For A SketchViews Needed For A Sketch
There are two types of drawings that you can sketch easily:
1. Pictorial drawing.
2. Multi-view Projection or Orthographic Projection.
28
Views Needed For A SketchViews Needed For A Sketch
Pictorial drawing -The width, height, and depth of an object are shown in one view.
29
30
Views Needed For A SketchViews Needed For A Sketch
Multi-view Projection or Orthographic Projection
An object is usually shown in more than one view.You do this by drawing sides of the object and relating them to each other.
31
32
OneOne--View SketchesView Sketches
If an object can be described in two dimensions, a one-view drawing is generally sufficient.
These objects generally have a depth or thickness that is uniform.
The drafter may just give the third dimension as a numerical value, instead of showing the third view.
33
34
35
TwoTwo--View SketchesView Sketches
Many objects can be described in twoviews.
Select the views carefully which describe the object well.
36
37
38
39
MultiMulti--View SketchesView Sketches
A pictorial drawing shows how the object looks in three-dimensional form.
However, a pictorial drawing may not show all the information desired.
Some of the lines and details may not be visible.
40
MultiMulti--view Sketchesview Sketches
41
The Glass BoxThe Glass Box
Use the "Glass box" to determine how many views are required to describe an object.
By "opening up" the glass box into one plane, you can see how it would be drawn on paper.
42
43
44
Materials For SketchingMaterials For Sketching
Sketching has two major advantagesover formal drawings.
Only a few materials are required to create a sketch.
Pencil, PaperYou can create a sketch anywhere. No drafting table required.
You are ready to sketch with a pencil, an eraser, and a pad of paper.
45
PaperPaper
Plain paper can be used for sketching.
If you need to refine the sketch, use tracing paper
46
PaperPaper
You may also use graph paper to control proportions while sketching.
Alternative: Place graph paper underneath plain paper.
47
PaperPaper
Generally 8-1/2 by 11 is the best sizefor making small sketches quickly.
48
PaperPaper
You can hold the paper on stiff cardboard, or a clipboard while working on it.
Place graph paper under the tracing paper to help guide line spacing.
49
Pencils and ErasersPencils and Erasers
Most drafters like to use soft lead pencils (Grades F, H, or HB).
Use an eraser that is good for soft leads,
Plastic eraser or kneaded-rubber eraser.
50
Pencils and ErasersPencils and Erasers
Four types of pencil points are used for sketching:
Sharp.Near-sharp.Near-dull.Dull.
51
Pencil SharpnessPencil Sharpness
52
Line Types UsedLine Types Used
Many line types are used in sketchingVisible.Hidden.Cutting Plane.Center Line.Construction Line.Extension Line.
Refer to Figure 2-33.
53
54
Drawing LinesDrawing Lines
Lines drawn freehand have a “natural look”.
The slight changes in direction show freedom of movement.
55
Drawing LinesDrawing Lines
To draw an object line:Hold the pencil far enough from the point that you can move your fingers easily and yet can put enough pressure on the point to make dense, black lines when necessary.
56
Drawing LinesDrawing Lines
To draw a construction line.Use very little pressure on the point.
They should be light enough that they need not be erased.
57
Drawing Straight LinesDrawing Straight Lines
Methods of Sketching Straight lines
1. Draw one continuous line.
58
Drawing Straight LinesDrawing Straight Lines
59
Drawing Straight LinesDrawing Straight Lines
2. Draw short dashes where the line should start and end.
Then, place the pencil point on the starting dash.
Keeping your eye on the end dash, draw toward it.
60
Drawing Straight LinesDrawing Straight Lines
61
Drawing Straight LinesDrawing Straight Lines
3. Draw a series of strokes that touch each other or are separated by very small spaces.
62
Drawing Straight LinesDrawing Straight Lines
63
Drawing Straight LinesDrawing Straight Lines
4. Draw a series of overlapping strokes.
64
Drawing Straight LinesDrawing Straight Lines
65
Drawing Straight LinesDrawing Straight Lines
Practice sketching straight lines beforeyou try to draw objects.
Draw vertical lines from the top down.
Draw horizontal lines from left to right if you are right handed (opposite if you are left handed).
66
Slanted Lines and Specific AnglesSlanted Lines and Specific Angles
Sketch slanted, or inclined lines from left to right.
It might be easiest to turn the paperand draw an inclined line the same way as a horizontal line.
67
Slanted Lines and Specific AnglesSlanted Lines and Specific Angles
68
Slanted Lines and Specific AnglesSlanted Lines and Specific Angles
When trying to sketch a specific angle, first draw a vertical line and a horizontal line to form a right angle.
Divide the right angle in half to form two 45 degree angles.Or divide in thirds to make 30 degree angles.
69
Slanted Lines and Specific AnglesSlanted Lines and Specific Angles
70
Drawing CirclesDrawing Circles
Sketch a circle
1. Estimate the length of the radius and mark it off.
Use the marks as guides, draw a square in which you can sketch the circle.
71
Drawing CirclesDrawing Circles
72
Drawing CirclesDrawing Circles
2. Draw very light centerlines and draw bisecting lines through the center at convenient angles.
Estimate the length of the radius and mark off this distance on all the lines.The bottom of the curve is generally easier to form, so draw it first.Then turn the paper so that the rest of the circle is on the bottom.Finish drawing the circle.
73
Drawing CirclesDrawing Circles
74
Drawing CirclesDrawing Circles
75
Drawing CirclesDrawing Circles
76
Drawing CirclesDrawing Circles
77
Drawing CirclesDrawing Circles
78
Drawing Circles/ArcsDrawing Circles/Arcs
79
Drawing CirclesDrawing Circles
3. Use your hand as a compassUse your little finger as a pivot at the center of the circle.Use your thumb and forefinger to hold the pencil rigidly at the radius you want.Turn the paper carefully under your hand.
80
81
Drawing CirclesDrawing Circles
4. Use two crossed pencilsHold them rigidly with the two points as far apart as the length of the desired radius.Put one pencil point at the center.Hold it there firmly and turn the paper, drawing the circle with the other point.
82
EDT 300/ENGR 306 83
ProportionsProportions
84
Proportions for SketchingProportions for Sketching
Sketches are not made to scale.
BUT, a good sketch should always maintain the correct proportion.
85
Estimating ProportionsEstimating Proportions
To sketch well, you must learn to eyeball (estimate by eye) an object's proportions.
86
Estimating ProportionsEstimating Proportions
To estimate an objects proportions:1. Look at an objects largest overall dimension, usually width, and estimate the size
2. Next determine the proportion of the height to the width
87
Technique In Developing ProportionsTechnique In Developing Proportions
Through practice you can train your eyeto work in two directions so that you can both divide and extend linesaccurately.
You should learn how to divide a line in half by estimating.
You can divide the halves to get fourths.
88
Technique In Developing ProportionsTechnique In Developing Proportions
Using a similar technique, you can expand lines one at a time
Start by drawing a line of one unit, then increase it by one equal unit so that it is twice as long as the first.Practice techniques both horizontally and vertically.
89
90
91
Making a Proportional SketchMaking a Proportional Sketch
Proportional Sketch Seven Step Process1. Observe the object
92
Making a Proportional SketchMaking a Proportional Sketch
Proportional Sketch Seven Step Process2. Select the views needed
93
Making a Proportional SketchMaking a Proportional Sketch
Proportional Sketch Seven Step Process3. Estimate proportions carefully.
Mark off major distances for width, height and depth in all three views.
94
Making a Proportional SketchMaking a Proportional Sketch
Proportional Sketch Seven Step Process4. Block in the enclosing rectangles
95
Making a Proportional SketchMaking a Proportional Sketch
Proportional Sketch Seven Step Process5. Locate the details in each of the views
96
Making a Proportional SketchMaking a Proportional Sketch
Proportional Sketch Seven Step Process6. Finish the sketch by darkening the object lines.
97
Making a Proportional SketchMaking a Proportional Sketch
Proportional Sketch Seven Step Process7. Add dimensions and notes as needed.
98
99
100
101