Lettering and Numbering

Lecture-2

Lettering and Numbering

Combination of straight lines and curves demonstrate the overall shape of the object while information about size, position and other properties of the object is expressed using words (combination of alphabets and digits). The appearance of the drawing depends significantly upon the letters and words placed on the drawing. Therefore, words should be inserted into the drawing properly and by following guidelines.

Writing of titles, dimensions, notes and other important particulars on a drawing is called lettering. It is an important part of a drawing. It is used to provide detailed specifications of an object. There could be various styles of writing Latin alphabets.

Lettering is used to provide easy to read and understand information to supplement a drawing in the form of notes and annotations. Lettering is an essential element in both traditional drawing and Computer Aided Design (CAD) drawing.

Main features of Lettering are:

· Legibility – shape & space between letters and words.

· Uniformity – size & line thickness.

Types of Lettering

Single-stroke letters:

These are the most basic forms of letters and are typically utilized in the majority of engineering drawings. The term single-stroke shouldn't be taken to mean that the letter must be created in one stroke without lifting the pencil. It actually means that the thickness of the line of the letter should be such as is obtained in one stroke of the pencil. The horizontal lines of letters should be drawn from left to right and vertical or inclined lines, from top to bottom.

Single-stroke letters are of two types:

(i) vertical and

(ii) inclined.

Inclined letters lean to the right, the slope being 75° with the horizontal.

Vertical Single Stroke

Inclined Single Stroke

Gothic/Double-stroke letters:

When more thickness is given to single stroke letters, it is known as double stroke or gothic letters.

Gothic/Double-stroke letters are of two types:

(i) vertical and

(ii) inclined.

Basics of Single Stroking

Rules for Lettering

The following rules should be observed while lettering:

1. Light guidelines drawn using sharp pencil ensures consistency in the size of the letter characters. If the lettering consists of capitals, draw only the cap line and base line. If the lowercase letters are included as well, draw the waist line and the drop line.

2. The thickness of the line of the letter should be such as is obtained in one stoke of pencil. Exert a firm uniform pressure, but not so heavy as to cut grooves in the sheet.

3. The width-to-height ratio should be around 1:2 for all capital alphabets (except I and W) and 1:3 for all numerals (except 1).

4. Letters should be written in capitals. Lower-case alphabet should be used only when they are accepted in international usage for abbreviations.

5. The horizontal lines of the letter should be drawn from left to right and vertical or inclined lines from top to bottom. Alphabet and numerals should neither touch each other nor the lines.

6. Letters and numerals should neither touch each other nor the lines.

7. Letters should be so spaced that the area between letters appears equal.

8. Words should be spaced one letter apart.

9. Letters should be so written that they appear upright from the bottom edge, except when they are used for dimensioning. For dimensioning, they may appear upright from the bottom edge for the right-hand side or the corner in between.

Drawing Graph for Lettering

Before drawing alphabets or numerals with proportions like 7:5, 5:4, or any other specified ratio, it is essential to first prepare a graph. This graph serves as a guide for maintaining the correct dimensions and uniformity of the lettering or numbering.

1. Start by determining the height of the lettering. Then, draw two parallel horizontal lines to define the upper and lower boundaries for the text.

2. Draw an inclined line at point A and divide it into 7, 5, or the required number of equal vertical squares or rhomboid sections of any suitable size. Then, connect point B₁ to point B.