ASME Y14.2-2014 pdf download

ASME Y14.2-2014 pdf download.Line Conventions and Lettering.
4 LINE CONVENTIONS Line conventions describe the size, construction, and application of the various lines used in making drawings. Paragraphs 4.1 through 4.14 identify the type and style of lines for use on drawings. 4.1 Line Widths Two widths of lines should be used on drawings (see Fig. 3-1). The ratio of line widths should be two-to-one (2:1). Recommended line widths are 0.3 mm minimum for thin lines and 0.6 mm minimum for thick lines. All lines of the same type shall be uniform throughout the drawing. 4.2 Line Spacing Spacing between parallel lines may be exaggerated to a maximum of 3 mm, so there is no fill-in when the drawing is reproduced. 4.3 Visible Lines Visible lines are continuous and shall be used for representing visible edges or contours of objects (see Figs. 3-1 and 4-1). 4.4 Projection Lines When used, projection lines indicate the line of sight between two successive orthographic views. See ASME Y14.3. 4.5 Hidden Lines When used, hidden lines represent hidden edges and contours. They consist of short evenly spaced dashes and are used to show the hidden features of an object. See Figs. 3-1 and 4-1. The length of the dashes may vary slightly in relation to the scale of the view. Hidden lines should begin and end with a dash in contact with the visible or hidden line from which they start or end, except when such a dash would form a continuation of a visible line or when a CAD system has limitations that cannot comply with these requirements. Dashes should join at corners, and arcs should start with dashes at tangent points. See Fig. 4-2. When features located behind transparent materials are depicted, they shall be treated as concealed features and shown with hidden lines. Hidden lines should be omitted when their use is not required for the clarity of the drawing. 4.6 Section Lines When used, section lines show surfaces cut by a cutting plane. They are drawn as a pattern of straight, equally spaced, parallel lines used to indicate the cut surfaces of an object in section views. See Figs. 3-1 and 4-1. 4.6.1 General Principles. Cut surfaces of sectional views may be identified by using section lines. Section lines are optional and may be used when necessary to distinguish individual components of an assembly or to distinguish different surface levels of a full or partial section through a part. See ASME Y14.3. Lettering should not be placed in section areas. However when it is unavoidable, the section lines shall be omitted in the area for the lettering. When several adjacent parts are shown in a section view, the parts may be sectioned as shown in Fig. 4-3. For section views of thin materials, see ASME Y14.3. 4.6.2 Direction and Spacing. Section lines should be drawn at a 45-deg angle within the view. See Fig. 4-3, illustration (a). On adjacent parts, the section lines should be drawn in the opposite direction. See Fig. 4-3, illustration (b). For additional adjacent parts, any suitable angle may be used to make each part stand out separately and clearly. See Fig. 4-3, illustration (c). A suitable angle should be chosen to avoid section lines that are parallel or perpendicular to visible lines. See Fig. 4-4. Section lines shall not meet at common boundaries. Section lines shall be uniformly spaced a minimum of 1.5 mm, and spaced as generously as possible and yet preserve the unity and contrast of the sectioned areas. See Fig. 4-5. Outline section lines are drawn adjacent to the boundaries only of the sectioned area, and may be used for large areas when section lines are required, provided clarity is not sacrificed. See Fig. 4-6. 4.7 Center Lines When used, center lines represent axes, center points, or center planes of symmetrical parts and features, bolt circles, and paths of motion. See Figs. 4-1 and 4-2.