CE En 112 Engineering Drawing with CAD Application Chapter 2: Sketching and Text (Lecture A)

Lecture Outline (Chap. 2) Technical sketching (2.1) Sketching technique (2.2) Proportions and construction lines (2.3) Introduction to projections (2.4) Multiview sketching technique (2.5) – next Monday Multiview sketches (2.6) – next Monday Lettering (2.8) Next class

Note that multiviews will be covered next Monday in detail. Objectives Define technical sketching (p.17 of Ch.2) Understand how sketching integrates into the design process (p.18 of Ch.2) Identify and define two types of sketches (pictorial & multiview – p.18 & 19 of Ch.2, p.32 of Ch.1) Create a design sketch using pencil Identify and use sketching tools (p.19 of Ch.2) Use grid paper to create sketches (p.20 of Ch.2) Lay out a sketch using proportions (Section 2.5 of Ch.2) Understand the difference between pictorial and multiview projection (Section 2.4 of Ch.2) Learn about a perspective sketch, an isometric sketch, an oblique sketch, and a multivew sketch (Section 2.6 of Ch.2) Identify the types and precedence of lines (Section 2.5 of Ch.2) Follow good hand-lettering practice (Section 1.16 of Ch.1) Note that multiviews will be covered next Monday in detail.

Technical Sketching (2.1) Technical Sketching is the process of producing a rough, preliminary drawing representing the main features of a product Generally less finished, structured, or restricted, and less time for its creation Tools include pencil, eraser, and paper (grid or blank) Means to create technical drawings Level of detail of freehand technical drawing

Technical Sketching (continued) Rough sketch Multi-view sketch Shaded sketch (Illustration) Pictorial sketch

Technical Sketching (continued) Technical sketches: used extensively in the first (ideation) stage of the design process to explore and solidify design ideas that form in the mind’s eye

Technical Sketching (continued) Transforming your ideas into tangible graphic images serves both as a permanent record of those ideas and as a means of encouraging creative thinking What’s the difference between the two figures below?

Sketching Technique (2.2) Sketching is based on the interactive process of seeing, imaging (forming structure and meaning of visual data), and representing (creating sketches of what our mind sees). The goal of technical sketching is simplification.

Sketching Technique (con’t) What do you see?

Sketching Technique (2.2) Practice Exercise 2.1 (Chapter 2, p. 21, [p.77]) Our perception is not limited to what we can see. Images often appear spontaneously in response to a memory recall. In this exercise, read the words and see if visual images are created in your mind’s eye. Your bedroom where you grew up as a child, or the street you lived on. A close relative, a famous actor, or a close friend from high school. A basketball sitting at center court on your high school gym floor. Your response to these written prompts is an example of your visual memory. You are thinking visually, which is a very powerful way of thinking when designing.

Sketching Technique (con’t) Contour sketching Sketching the outline of an object – most fundamental element to creating sketches Negative space sketching Sketch in which you concentrate on the spaces between the objects, not on the object itself Upside-down sketching Turn an object upside-down before sketching so that you can concentrate on the shape and form of the object

Sketching Technique (con’t) Straight lines Sketching lines are often drawn by a sequence of two or three passes with the pencil Techniques used to sketch straight lines: Orient the paper to a comfortable position. Do not fix the paper to the surface Mark the endpoints of the lines to be sketched Determine the most comfortable method of creating lines, such as drawing from left to right, or drawing either away from or toward your body Relax your hand and the rest of your body Use the edge of the paper as a guide for making straight lines Draw long lines by sketching a series of connected short lines If necessary, draw on grid paper or on tracing paper that is overlain on grid paper

Sketching Technique (con’t) Curved lines Use multiple guide points

Proportions & Construction Lines (2.3) The ratio between two dimensions of an object Represented by a series of preliminary (construction) lines, drawn light and fast, which may or may not represent the locations of the final lines in the sketch The relative proportions of the primary dimensions of an object is more important than their actual physical sizes *Note: If a drawing doesn’t look or feel right, it probably isn’t

Proportions & Construction Lines (con’t) Example of relative proportions: Standard proportions for the United States flag

Proportions & Construction Lines (con’t) Creating a proportioned sketch: Step 1: Gage the proportion of the overall size of the object. Lightly draw construction lines to create a bounding box Step 2: Inside bounding box, draw major features of object Step 3: Continue to draw bounding boxes until all features are represented Step 4: Begin sketching the final line work (dark) Comic book writers may distort proportions.

Introduction to Projections (2.4) Projections: developed to represent 3-D images on 2-D media Four basic types of projections: Multiview Axonometric Oblique Perspective B, C, and D are pictorial because they represent the object as a 3-D form More to come in future lectures…

Multiview Sketching Technique (2 Multiview Sketching Technique (2.5) – (Slide 18 through 24 to be covered next Monday.) Precedence of lines (when these lines overlap…) Visible line > Hidden line and cutting line> Center line Conventional practices for circles and arcs Short center segment, 3mm; long segment, 20-40 mm; space, 1 to 1.5 mm. May repeat these when a long center line is needed

Multiview Sketching Technique (con’t) Hidden line conventions must be followed in multiview sketching Review these conventions and we will discuss them further in later lectures

Multiview Sketches (2.6) One-view, two-view, three-view sketches depending on the complexity of the object. Refer to the text for the steps in determining which to use – we will also discuss more in later lectures…

Multiview Sketches (con’t) Three image planes

Multiview Sketches (con’t) Visualization Techniques: Object – Image plane – The eye of the reviewer relationship Horizontal, vertical, and depth

Multiview Sketches (con’t) We will cover this topic later. Three types of faces: 1. Normal 2. Inclined

Multiview Sketches (con’t) We will cover this topic later. 2. Inclined Inclined vs. Oblique faces: Can you tell the difference? 3. Oblique

Lettering (2.8) Lettering standards Use ⅛” or 3 mm for most text height Use ¼” or 6 mm for the height of fractions Space between lines of text  Take the text height and divide it by 3 Hand lettering Use guide lines (thin, light construction lines) Maintain uniform spacing between lines Font and point Font means “style” (like Gothic and Courier); point means the size of letters Good/poor lettering Legibility is very important Remember neatness counts! Why text in the drawing? 1. To communicate non-graphic info; 2. As a substitute for graphic information (e.g., title block, revision block, bill of materials, general notes, dimensions, etc.)

Lettering (con’t) Lettering dimensions: Examples of lettering:

Next Monday Class Read Chapter 2, starting Section 2.4 in page 29 [p. 85]. Open up the lecture link to see the sections that will be covered next Monday.