Machinery's Handbook, 31st Edition
2070
Centralizing Acme Screw Threads Table 10. American National Standard Centralizing Acme Single-Start Screw Threads—Pitch Diameter Allowances ANSI/ASME B1.5-1997 (R2014) Nominal Size Range a Allowances on External Threads b Nominal Size Range a Allowances on External Threads b
Centralizing Class 3C, . D 0006
Centralizing Class 3C, . D 0006
To and Including
To and Including
Class 2C, . D 0008
Class 4C, . D 0004
Class 2C, . D 0008
Class 4C, . D 0004
Above
Above
0
0.0024 0.0040 0.0049 0.0057 0.0063 0.0069 0.0075 0.0080 0.0085 0.0089 0.0094
0.0018 0.0030 0.0037 0.0042 0.0047 0.0052 0.0056 0.0060 0.0064 0.0067 0.0070
0.0012 0.0020 0.0024 0.0028 0.0032 0.0035 0.0037 0.0040 0.0042 0.0045 0.0047
0.0098 0.0105 0.0113 0.0120 0.0126 0.0133 0.0140 0.0150 0.0160 0.0170 0.0181
0.0073 0.0079 0.0085 0.0090 0.0095 0.0099 0.0105 0.0112 0.0120 0.0127 0.0136
0.0049 0.0052 0.0057 0.0060 0.0063 0.0066 0.0070 0.0075 0.0080 0.0085 0.0091
1 9 ∕ 16 1 7 ∕ 8 2 1 ∕ 8 2 3 ∕ 8 2 5 ∕ 8 2 7 ∕ 8 3 1 ∕ 4 3 3 ∕ 4 4 1 ∕ 4 4 3 ∕ 4 5 1 ∕ 2
1 7 ∕ 16 1 9 ∕ 16 1 7 ∕ 8 2 1 ∕ 8 2 3 ∕ 8 2 5 ∕ 8 2 7 ∕ 8 3 1 ∕ 4 3 3 ∕ 4 4 1 ∕ 4 4 3 ∕ 4
3 ∕ 16 5 ∕ 16 7 ∕ 16 9 ∕ 16
3 ∕ 16 5 ∕ 16 7 ∕ 16 9 ∕ 16
11 ∕ 16 13 ∕ 16 15 ∕ 16
11 ∕ 16 13 ∕ 16 15 ∕ 16 1 1 ∕ 16 1 3 ∕ 16 1 5 ∕ 16
1 1 ∕ 16 1 3 ∕ 16 1 5 ∕ 16 1 7 ∕ 16
All dimensions are given in inches. It is recommended that the sizes given in Table 9 be used whenever possible. a The values in columns for Classes 2C, 3C, and 4C are to be used for any size within the nominal size range columns. These values are calculated from the mean of the range. b An increase of 10 percent in the allowance is recommended for each inch, or fraction thereof, that the length of engagement exceeds two diameters. Table 11. American National Standard Centralizing Acme Single-Start Screw Threads—Pitch Diameter Tolerances ANSI/ASME B1.5-1997 (R2014)
Class of Thread and Diameter Increment
Class of Thread and Diameter Increment
Nom. Dia., a D
Nom. Dia., a D
2C
3C
4C
2C
3C
4C
. D 0006
. D 00028
. D 0002
. D 0006
. D 00028
. D 0002
.00300 .00335 .00367 .00397 .00424 .00474 .00520 .00561 .00600 .00636 .00671 .00704
.00140 .00157 .00171 .00185 .00198 .00221 .00242 .00262 .00280 .00297 .00313 .00328
.00100 .00112 .00122 .00132 .00141 .00158 .00173 .00187 .00200 .00212 .00224 .00235
.00735 .00794 .00849 .00900 .00949 .00995 .01039 .01122 .01200 .01273 .01342
.00343 .00370 .00396 .00420 .00443 .00464 .00485 .00524 .00560 .00594 .00626
.00245 .00265 .00283 .00300 .00316 .00332 .00346 .00374 .00400 .00424 .00447
1 1 ∕ 2 1 3 ∕ 4 2 1 ∕ 4 2 1 ∕ 2 2 3 ∕ 4 2
1 ∕ 4
5 ∕ 16
3 ∕ 8
7 ∕ 16
1 ∕ 2 5 ∕ 8 3 ∕ 4 7 ∕ 8
3
3 1 ∕ 2
1
4
1 1 ∕ 8 1 1 ∕ 4 1 3 ∕ 8
4 1 ∕ 2
5
…
…
…
…
Class of Thread and Pitch Increment
Class of Thread and Pitch Increment
Thds. per Inch, n
Thds. per Inch, n
2C
3C
4C
2C
3C
4C
. n 0030 1 .
n 0014 1 .
n 0010 1 .00250
. n 0030 1 .
n 0014 1 .
n 0010 1 .00500
16 14 12 10
.00750 .00802 .00866 .00949 .01061 .01225 .01342
.00350 .00374 .00404 .00443 .00495 .00572 .00626
4 3
.01500 .01732 .01897 .02121 .02449 .02598 .03000
.00700 .00808 .00885 .00990 .01143 .01212 .01400
.00267 .00289 .00316 .00354 .00408 .00447
.00577 .00632 .00707 .00816 .00866 .01000
2 1 ∕ 2
2
8 6 5
1 1 ∕ 2 1 1 ∕ 3
1
All dimensions are given in inches. For any particular size of thread, the pitch diameter tolerance is obtained by adding the diameter increment from the upper half of the table to the pitch increment from the lower half of the table. Example: A 0.250-16-ACME-2C thread has a pitch diameter tolerance of 0.00300 + 0.00750 = 0.0105 inch. The equivalent tolerance on thread thickness is 0.259 times the pitch diameter tolerance. a For a nominal diameter between any two tabulated nominal diameters, use the diameter increment for the larger of the two tabulated nominal diameters.
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