ASME Y14.31 pdf free download

ASME Y14.31 pdf free download Undimensioned Drawings Engineering Drawing and Related Documentation Practices
5.2 Grid Lines When used, grid lines shall be added and validated for accuracy before the drawingis started. The pattern of perpendicular lines shall be equally spaced at a nominal distance apart. Preferred grid line spacing is 5.000 in. (127 mm) or 10.000 in. (254 mm). Drawings with grid lines shall indicate directly or by reference the dimen- sions of the grid with a note such as GRID LINES 10.000 IN. (254 MM) ON CENTER. The pattern of grid lines may be parallel to the drawing borders or rotated at an appropriate angle to suitthe presentationofthe item(see Figs. 5 and 13). When grid lines are rotated, dimensional accuracy points are required independent of the grid for validation and verification. Portions of grid lines may be removed in areas where they interfere with the clarity or presentation of pictorial views. An area of approxi- mately 1 in. (25.4 mm) diameter at the grid intersection points shall be retained.
5.3 Dimensional Accuracy Points Dimensional accuracy points may be constructed as shown in Fig. 14. Dimensional accuracy points are fre- quently identified by terms such as, trammel points, grid check points, and material validation points. The type and size of dimensional accuracy points shall be consistent throughout the drawing and shall be placed in a rectangular pattern surrounding the item.A minimum set of four dimensional accuracy points shall be placed within the drawing border. Dimensional accu- racy points shall be validated for accuracy. The horizontal and vertical dimensions between dimensional accuracy points shall be controlled directly or by refer- ence. When controlled directly, extend arrows horizontally and vertically with dimensions indicating the distance to the adjacent dimensional accuracy points in the pattern (see Fig. 15). When the drawing exceeds the capabilities of the validation and verification process, a minimum set of six dimensional accuracy points shall be provided (see Fig. 16). The center dimensional accuracy point shall be constructed as shown in Fig. 14. The dimensionalaccuracypointsshallbeequallyspacedhor- izontally and equally spaced vertically.
5.4 Registration Marks Registration marks are used in place of a grid system on drawings depicting artwork type items. A minimum of three registration marks shall be placed in a right triangular pattern surrounding the artwork pattern (see Figs. 6 and 17).
6 SHEET ARRANGEMENT When the size of an item requires splitting into multi- ple views, the break of the view shall take place near a designated common reference. Each view shall be extended past the designated common references and end in a break line to indicate that the designated com- mon reference is not the end of the item. Designated common references may coincide with grid lines and shall be identified with a note such as COMMON REFERENCE (see Figs. 18 and 19).
6.1 Split Views on Same Sheet When views of the item are split on the same sheet, there shall be a minimum image overlap of 3 in. (76 mm) from the designated common reference (see Fig. 18).
6.2 Split Views on Multiple Sheets When views of the item are split over multiple sheets, the views shall have a minimum image overlap of 3 in. (76 mm) from the designated common reference. Sheets may be positioned one above the other or side-by-side when designated common references are used. When two or more sheets are joined in this manner, a sheet arrangementdiagram shallbe provided on the firstsheet to indicate the relative positions of the sheets and as an aid in selecting the sheet on which desired information is located (see Fig. 19).
7 TOLERANCES
7.1 Graphical Tolerances All features of the item shown in the graphical repre- sentation shall be drawn to a tolerance of ±0.010 in. (0.25 mm) of the actual size and location.
7.2 Item Tolerances
7.2.1 For contour definition drawings, templates, and comparator drawings, the lines defining an undi- mensioned item shall be considered as being the true profile. Tolerances shall be applied to measurements taken from the center of each line. 7.2.2 For wire harness drawings, the lines defining the center line of the wire harness shall be considered the true location and length. Plus or minus tolerances shallbespecifiedonthe drawingindicatingthe tolerance for the length of the wire harness. 7.2.3 For printed circuit boards, the lines defining the conductors shall be considered the true location. Tolerances are based on the components grid pattern per IPC-2221.