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Object of this course is to learn the Auto CAD. Types of Lines and their usage. Drawing Instruments and usage, Sheet Planning and Dimensioning, Orthographic projection, First and Third Angle, Sectional Drawing, Isometric Drawing, Assembly Drawing and Standard part drawing. This file contains: Lines, Leterring, Types, Pencil, Grades, Strokes, Artistic, Cursive, Symmetrical, Width, Height
Typology: Slides
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Chapter 2
Lines are like the alphabet of a drawing language. Each line in a drawing is used in a specific sense.
Types of Lines The basic types of lines are shown in Table 2.1. Their applications are illustrated in Fig.2.1.
Pencil Grades An H grade pencil is advised for THICK and MEDIUM lines. THIN lines may be drawn by a 2H grade pencil.
Line Strokes
Line strokes refer to the directions of drawing straight and curved lines, Fig. 2.2. Horizontal lines are drawn from left to right, vertical and inclined lines are drawn from top to bottom. Curved lines (e.g., arcs of circles) are also drawn from left to right or top to bottom. Right (or upper) half of a circle is drawn clockwise while left (or lower) half is drawn anticlockwise.
Lettering is an art of writing text on a drawing by using alphabets, numerals and symbols. Two types of lettering are commonly used — (1) single stroke, and (2) double stroke. Single stroke or double stroke letters may be vertical or inclined, Fig. 2.3. The line width of a double stroke letter is greater than that of a single stroke letter.
Height and Width of Letters
BIS (SP 46: 2003) has recommended the heights of letters as: 1.8 mm, 2. mm, 3.5 mm, 5 mm, 7 mm, 10 mm, 14 mm and 20 mm. Large-sized letters are used for main titles and headings, medium-sized letters for subtitles and important notes and small-sized letters for dimensions and general notes. The height of letters bears direct relationship with the size of drawing, i.e., large-sized letters for larger drawings and small-sized letters for smaller drawings. The height-to-width ratio varies from letter to letter. Most of the letters follow the ratio 7 : 5 or 7 : 6.
Lettering Practice
To start with, lettering may be done with instruments, i.e., lettering set- squares (Fig. 1.17) or specially designed lettering triangles. Rounded corners and curved letters (e.g., S, 8, etc.) should be drawn freehand. After sufficient practice, lettering may be completely done freehand. The instruments may be used for reference.
Pencil Grade An H grade pencil is the best choice for single stroke lettering. An HB grade pencil may be used for freehand lettering.
Hand Strokes Practice of line strokes as mentioned in Section 2.2.5 is extremely essential to ensure the speed in freehand lettering.
Use of Grid/Guide Lines Initially, the grid as shown in Fig. 2.6 may be used for lettering practice. It ensures the proportion of each letter. Guide lines provide an alternative to a grid. Three horizontal guide lines for capital letters and four horizontal guidelines for lowercase letters, Fig. 2.7, may be used initially. After sufficient practice, two horizontal guide lines (for capital letters and lowercase letters), should be used.
Spacing The adjacent letters in a word are so placed that the background areas between them are seen approximately equal.
