Ch.3 Sketching, Text, and Visualization What’s technical sketching? (3.1) Sketching techniques (3.2) Use construction lines wisely to maintain proper proportions (3.3) Intro to projections (3.4) Multi-view sketching technique (3.5) Multi-view sketches (3.6) Lettering and Text on drawings (3.8) Visualization for design (3.9) Visualization techniques for engineering drawings (3.12)

Technical sketching (3.1) The process of producing a rough, preliminary drawing representing the main features of a product or structure. Generally less finished, less structures or restricted, and less time for its creation. Use either grid paper or blank paper. Means to create technical drawings Level of detail of freehand technical drawing

Visualization for design (3 Visualization for design (3.9): Transforming your ideas into tangible graphic images serves both as a permanent record of those ideas and as a means of encouraging further creative thinking. What’s the difference between the two figures below.

Freehand sketches – the level of detail Multi-view sketch Rough sketch Shaded sketch Pictorial sketch

Sketching technique (3.2) Straight lines Sketching lines are often drawn by a sequence of two or three passes with the pencil. See p.148 for hints. (and Practice!) Curved lines Use multiple guide points. See p.149-150 for hints. Ellipses A scrap of paper can be used to create an ellipse, using the trammel method. See p.149-150.

Lettering (3.7) and text on drawings (3.8) Lettering standards Use 1/8” or 3 mm for most text height Use ¼” pr 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). See p.173. Maintain uniform spacing between lines. Font and point Font means “style” (like Gothic and Courier); point means the size of letters Good/poor lettering Examine Fig. 3.54 carefully! Remember neatness counts! Why text in the drawing? 1. To communicate non-graphic info; 2. As a substitute for graphic info. E.g. Title block, Revision block, Bill of materials, General notes, Dimensions

Lettering examples

Proportions and Construction Lines The relative proportions of the primary dimensions of an object is more important than their actual physical sizes. A proportion is the ratio between any two dimensions of an object.  Go through the exercises in p.151-153, step by step to get used to the concept.

Intro to projections: Learn how to create pictorials and multi-view sketches (& know the differences among them)

Multi-view sketches (3.6) One-view, two-view, 3-view sketches. Depends on the complexity of the object. See p. 170-171 for the steps

Three image planes

Visualization techniques for engineering drawings Object – Image plane – The eye of the reviewer relationship Horizontal, vertical, and depth

Multi-view sketching techniques (3.5): Basics 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

3 types of faces: Normal face, Inclined face, and Oblique face Normal faces Inclined

Inclined vs. Oblique faces: Can you tell the difference? Inclined face Oblique face