Machinery's Handbook, 31st Edition
2026 Metric Screw Threads M Profile Table 11. ANSI Standard Pitch-Diameter Tolerances of External Metric Threads, Td 2 ISO 965/1 ANSI/ASME B1.13M-2005 (R2015) Basic Major Diameter, d Pitch P Tolerance Grade Over Up to and incl. 3 4 a 5 6 a 7 8 9 180 355 3 0.125 0.160 0.200 0.250 0.315 0.400 0.500 4 0.140 0.180 0.224 0.280 0.355 0.450 0.560 6 0.160 0.200 0.250 0.315 0.400 0.500 0.630 8 0.180 0.224 0.280 0.355 0.450 0.560 0.710 a Tabulated in this Standard for M threads. All dimensions are in millimeters. Tolerance Grade Comparisons.— The approximate ratios of the tolerance grades shown in Table 8, Table 9, Table 10, and Table 11 in terms of Grade 6 are as follows: Minor Diameter Tolerance of Internal Thread: Grade 6 is TD 1 ( Table 8 ): Grade 4 is 0.63 TD 1 (6); Grade 5 is 0.8 TD 1 (6); Grade 7 is 1.25 TD 1 (6); and Grade 8 is 1.6 TD 1 (6). Pitch Diameter Tolerance of Internal Thread: Td 2 ( Table 10 ): Grade 4 is 0.85 Td 2 (6); Grade 5 is 1.06 Td 2 (6); Grade 6 is 1.32 Td 2 (6); Grade 7 is 1.7 Td 2 (6); and Grade 8 is 2.12 Td 2 (6). It should be noted that these ratios are in terms of the Grade 6 pitch diameter toler ance for the external thread. Major Diameter Tolerance of External Thread: Td (6) ( Table 9 ): Grade 4 is 0.63 Td (6); and Grade 8 is 1.6 Td (6). Pitch Diameter Tolerance of External Thread: Td 2 ( Table 11 ): Grade 3 is 0.5 Td 2 (6); Grade 4 is 0.63 Td 2 (6); Grade 5 is 0.8 Td 2 (6); Grade 7 is 1.25 Td 2 (6); Grade 8 is 1.6 Td 2 (6); and Grade 9 is 2 Td 2 (6). Standard M Profile Screw Threads, Limits of Size.— The limiting M profile for internal threads is shown in Fig. 6 with associated dimensions for standard sizes in Table 12. The limiting M profiles for external threads are shown in Fig. 7 with associated dimensions for standard sizes in Table 13. If the required values are not listed in these tables, they may be calculated using the data in Table 3, Table 6, Table 7, Table 8, Table 9, Table 10, and Table 11 together with the preceding formulas. If the required data are not included in any of the tables listed above, reference should be made to Sections 6 and 9.3 of ANSI/ASME B1.13M, which gives design formulas. Table 11. (Continued) ANSI Standard Pitch-Diameter Tolerances of External Metric Threads, Td 2 ISO 965/1 ANSI/ASME B1.13M-2005 (R2015)
H 24
H 8
H 2
0.5 T D 2
0.5 T D 1
H 4
D Basic Major Dia.
D Max. Major Dia.*
Basic Profile
H 4
D 2 Max. Pitch Dia.
D 1 Max. Minor Dia.
D 1 Basic Minor Dia.
D 2 Basic Pitch Dia.
Fig. 6. Internal Thread—Limiting M Profile. Tolerance Position H (See footnote a to Table 12)
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