ASME Y14.2-2008 pdf – Line Conventions and Lettering.
2.11 Break Line
Break lines are used when complete views are not required. The two forms of break lines are
(a) freehand line [see Fig. 1 (line 12) and Fig. 2]
(b) long lines joined by zigzags [see Fig. I (line 13) and Fig. 11, illustration (a)]
2.12 Phantom Line
Phantom lines are used to indicate
(a) alternate positions of moving parts (see Fig. 2)
(b) reference parts [see Fig. ii, illustration (a)]
(c) repeated detail [see Fig. 11, illustrations (b) and (c)]
(d) filleted and rounded corners [see Fig. 11, illustration (d)]
(e) a reference plane between adjacent orthographic views
Phantom lines consist of long lines separated by pairs of short dashes. Phantom lines should start and end with long lines which may vary in length depending on the size of the drawing [see Fig. I (line 14)].
2.13 Stitch Line
Stitch lines are used for indicating a sewing or stitching process [see Fig. 1 (lines 15 and 16)1. The two forms of stitch lines are as follows:
(a) short dashes and spaces of equal lengths
(b) dots approximately 0.3 mm diameter, and 3 mm apart
2.14 Chain Line
Chain lines are used to indicate a surface or surface zone receiving additional treatment or consideration within limits specified on the drawing (see Fig. 2). They may also be used to indicate the location of a projected tolerance zone as defined in ASME Y14.5M. Chain lines consist of alternating lines and short dashes [see Fig. 1 (line 17)].
Arrowheads are used to terminate dimension, leader, and cutting and viewing plane lines (see paras. 2.9.1, 2.9.3, and 2.10). Arrowhead length and width should be a ratio of approximately 3:1. The width of the arrowhead should be proportionate to the thickness of the lines used. A single style of arrowhead shall be used throughout the drawing (see Fig. 12).
For clarity within this Standard, lettering means both letters and numerals. Paragraphs 4.1 through 4.6 identify the type and style of lettering for use on drawings.
4.1 Lettering Type
Lettering should be single stroke gothic, opaque, and well spaced characters as shown in Figs. 13 and 14. When additions or revisions are made to a drawing, the original style of lettering shall be maintained.
4.2 Letter Style
Either inclined or vertical lettering is permissible. Only one style of lettering shall be used throughout a drawing. The preferred slope for the inclined characters is approximately 68 deg from the horizontal (see Fig. 13).
4.3 Letters — Upper and Lower Case
Upper case letters shall be used for all lettering on drawings unless lower case letters are required (see Figs. 13 and 14).
4.4 Letter Height
The minimum letter heights for various size drawings are shown in Tables 1 and 1-1.
4.5 Letter Spacing
Letters in words should be spaced so the background areas between the letters are approximately equal, and words are clearly separated. The space between two numerals having a decimal point between them is to be a minimum of two-thirds the height of the lettering. The vertical space between lines of lettering shall be no more than the height of the lettering, or no less than half the height of the lettering.
4.6 Legibility
The lettering heights, spacing, and proportions in Figs. 13 and 14, and also Table 1, normally provide acceptable reproduction. When applying lettering manually, or by typewriter, or CAD equipment which utilizes heights, spacing, or proportions other than those recommended, the lettering is acceptable when the minimum legibility and reproduction requirements of the accepted industry or military reproduction specifications are met. Therefore, the basic requirement for lettering on a drawing is to produce fully legible copies.