Table 12. American National Standard Centralizing Acme Single-Start Screw Threads— Tolerances and Allowances for Major and Minor Diameters ANSI/ASME B1.5-1997 (R2014)
Allowance From Basic Major and Minor Diameters (All Classes)
Tolerance on Major Diameter Plus on Internal, Minus on External Threads
Internal Thread
Class 2C
Class 3C
Class 4C
Tolerance on Minor Diam, b , c All Internal Threads, (Plus 0.05 P )
Major Diam, e (Plus . D 00010
External Thread,
Internal Thread,
External Thread,
Internal Thread,
External and Internal Threads, . D 00035
Minor Diam, d All External
Thds a per Inch
Minor Diam, d (Plus 0.1 P )
. D 00015
. D 00035
. D 00010
. D 00020
Size (Nom.)
Threads (Minus)
16 14 12 12 10
0.010 0.010 0.010 0.010 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020
0.0005 0.0006 0.0006 0.0007 0.0007 0.0008 0.0009 0.0009 0.0010 0.0011 0.0011 0.0012 0.0012 0.0013 0.0014 0.0015 0.0016 0.0017 0.0017 0.0019 0.0020 0.0021 0.0022
0.0062 0.0071 0.0083 0.0083 0.0100 0.0125 0.0167 0.0167 0.0200 0.0200 0.0200 0.0250 0.0250 0.0250 0.0250 0.0333 0.0333 0.0333 0.0500 0.0500 0.0500 0.0500 0.0500
0.0050 0.0050 0.0050 0.0050 0.0050 0.0062 0.0083 0.0083 0.0100 0.0100 0.0100 0.0125 0.0125 0.0125 0.0125 0.0167 0.0167 0.0167 0.0250 0.0250 0.0250 0.0250 0.0250
0.0017 0.0020 0.0021 0.0023 0.0025 0.0028 0.0030 0.0033 0.0035 0.0037 0.0039 0.0041 0.0043 0.0046 0.0049 0.0052 0.0055 0.0058 0.0061 0.0065 0.0070 0.0074 0.0078
0.0007 0.0008 0.0009 0.0010 0.0011 0.0012 0.0013 0.0014 0.0015 0.0016 0.0017 0.0018 0.0018 0.0020 0.0021 0.0022 0.0024 0.0025 0.0026 0.0028 0.0030 0.0032 0.0034
0.0017 0.0020 0.0021 0.0023 0.0025 0.0028 0.0030 0.0033 0.0035 0.0037 0.0039 0.0041 0.0043 0.0046 0.0049 0.0052 0.0055 0.0058 0.0061 0.0065 0.0070 0.0074 0.0078
0.0005 0.0006 0.0006 0.0007 0.0007 0.0008 0.0009 0.0009 0.0010 0.0011 0.0011 0.0012 0.0012 0.0013 0.0014 0.0015 0.0016 0.0017 0.0017 0.0019 0.0020 0.0021 0.0022
0.0010 0.0011 0.0012 0.0013 0.0014 0.0016 0.0017 0.0019 0.0020 0.0021 0.0022 0.0023 0.0024 0.0026 0.0028 0.0030 0.0032 0.0033 0.0035 0.0037 0.0040 0.0042
1 ∕ 4
5 ∕ 16
3 ∕ 8
7 ∕ 16
1 ∕ 2 5 ∕ 8 3 ∕ 4 7 ∕ 8 1
8 6 6 5 5 5 4 4 4 4 3 3 3 2 2 2 2 2
1 1 ∕ 8 1 1 ∕ 4 1 3 ∕ 8 1 1 ∕ 2 1 3 ∕ 4 2 1 ∕ 4 2 1 ∕ 2 2 2 3 ∕ 4 3 1 ∕ 2 3 4 4 1 ∕ 2
5 0.0045 a All other dimensions are given in inches. Intermediate pitches take the values of the next coarser pitch listed. Values for intermediate diameters should be calculated from the formulas in column headings, but ordinarily may be interpolated. b To avoid a complicated formula and still provide an adequate tolerance, the pitch factor is used as a basis, with the minimum tolerance set at 0.005 in. c Tolerance on minor diameter of all external threads is 1.5 × pitch diameter tolerance. d The minimum clearance at the minor diameter between the internal and external thread is the sum of the values in columns 3 and 5. e The minimum clearance at the major diameter between the internal and external thread is equal to column 4.
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