Lettering is an essential element in both traditional drawing and CAD drawing. Graphic communication is often not enough to completely describe an object. Lettered text is often necessary to provide detailed specifications about the drawn object. And there are a number of formal rules that apply to the placement of lettering.
Commercial Gothic, also called sans-serif Gothic, is the lettering style of most interest to engineers. It is plain and legible. While admittedly not as beautiful as many other styles, sans-serif letters are comparatively easy to make. They may be drawn in outline and then filled in.
C.W. Reinhardt, formerly chief draftsman for Engineering News, developed alphabets of capital and lowercase inclined and “vertical letters, based on the old Gothic letters. For each letter, he worked out a systematic series of strokes.
Reinhardt’s development of single-stroke letters was the first step toward standardization of technical lettering. In 1935, the American National Standards Institute (ANSI) suggested letter forms that are now generally considered as standard.
Lettering is freehand drawing and not writing. Therefore, the six fundamental strokes and their direction for freehand drawing are basic to lettering. The horizontal lines are drawn to the right and all vertical, inclined, and curved strokes are drawn downward.
Either vertical or inclined letters may be used, but only one style should appear on any one drawing. Vertical letters are perhaps slightly more legible than inclined letters, but they are more difficult to execute. Both vertical and inclined letters are standard, and the engineer or drafter may be called on to use either.
Background areas between letters and words should appear approximately equal, and words should be clearly separated by a space equal to the height of the lettering. Only when special emphasis is necessary should the lettering be underlined. Also, it is not...