page_title: Technical lettering
section_title: Dimensions of letters
hierarchical_section_title: Technical lettering / Dimensions of letters
caption_attribution_description: English: Dimensioning of Letters
context_page_description: Technical lettering is the process of forming letters, numerals, and other characters in technical drawing. It is used to describe, or provide detailed specifications for, an object. With the goals of legibility and uniformity, styles are standardized and lettering ability has little relationship to normal writing ability. Engineering drawings use a Gothic sans-serif script, formed by a series of short strokes. Lower case letters are rare in most drawings of machines.
context_section_description: The Nominal Size of lettering is defined by the height (h) of the outline contour of the upper-case (capital).
  Central Line is the imaginary line in the middle of each line or line element which is a constitutive part of a graphic character set.
  If we consider d as the width of the line element and h as the height of the line element, then the two standard ratios for d/h are: 1/14 and 1/10, which are feasible because they result in a minimum number of line thicknesses.
  Location of Central Lines –  The nominal size (h) and the spacing between characters (a) shall be taken as the basis for defining the central line.
  Range of Nominal Sizes – The nominal size is typically one of the sequence 2.5 mm, 3.5 mm, 5 mm, 7 mm, 10 mm, 14 mm, 20 mm.  Successive members of this sequence are approximately in a ratio of the square root of 2, as in the ISO 216 series of paper sizes.
  Lettering Angle – The lettering may be vertical (upright) or inclined (sloped) to the right at 75° from the horizontal. Compare oblique type.
  The spacing between two characters may be reduced by half, if this gives a better visual effect.
  Various letters are divided into number of parts so that dimensions will be accurate. 
  The size of letter is described by its height. According to the height of letters, they are classified as Lettering A or Lettering B.
caption: Dimensioning of Letters
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