美制外螺纹（2A）常用规格极限尺寸表（粗牙）

美制外螺纹（2A）常用规格极限尺寸表（粗牙）
公称尺寸和每英寸牙数螺纹系列代号大径极限中径极限小径max螺胚直径最小最大最小最大最小最大
8-32UNC _0.1571 __0.1631 __0.1399 __0.1428 __0.1248 _3.58 3.61 (0.164-32)3.9903 4.1427 3.5535 3.6271 3.1699
10-24_0.1818 __0.1890 __0.1586 __0.1619 __0.1379 _4.07 4.10 (0.190-24)4.6177 4.8006 4.0284 4.1123 3.5027
12-24_0.2078 __0.2150 __0.1845 __0.1879 __0.1639 _4.72 4.75 (0.216-24)5.2781 5.4610 4.6863 4.7727 4.1631
1/4-20_0.2408 __0.2489 __0.2127 __0.2164 __0.1876 _5.45 5.48 (0.250-20)6.1163 6.3221 5.4026 5.4966 4.7650
5/16-18_0.3026 __0.3113 __0.2712 __0.2752 __0.2431 _6.94 6.98 (0.3175-18)7.6860 7.9070 6.8885 6.9901 6.1747
3/8-16_0.3643 __0.3737 __0.3287 __0.3331 __0.2970 _8.40 8.44 (0.375-16)9.2532 9.4920 8.3490 8.4607 7.5438
7/16-14_0.4258 __0.4361 __0.3850 __0.3897 __0.3485 _9.83 9.87 (0.4375-14)10.8153 11.0769 9.7790 9.8984 8.8519
1/2-13_0.4876 __0.4985 __0.4435 __0.4485 __0.4041 _11.34 11.38 (0.50-13)12.3850 12.6619 11.2649 11.3919 10.2641 9/16-12_0.5495 __0.5609 __0.5016 __0.5068 __0.4587 _12.80 12.84 (0.5625-12)13.9573 14.2469 12.7406 12.8727 11.6510
5/8-11_0.6113 __0.6234 __0.5589 __0.5644 __0.5119 _14.27 14.32 (0.625-11)15.5270 15.8344 14.1961 14.3358 13.0023
3/4-10_0.7353 __0.7482 __0.6773 __0.6832 __0.6255 _17.28 17.33 (0.750-10)18.6766 19.0043 17.2034 17.3533 15.8877
7/8-9_0.8592 __0.8731 __0.7946 __0.8009 __0.7368 _20.27 20.32 (0.875-9)21.8237 22.1767 20.1828 20.3429 18.7147 1"-8_0.9830 __0.9980 __0.9100 __0.9168 __0.8446 _23.22 23.27 (1.000-8)24.9682 25.3492 23.1140 23.2867 21.4528 1.螺胚直径指滚丝前的尺寸，数值为依经验公式计算而得，在实践中需验证。 2.标记示例：10-24UNC-2A(或0.190-24UNC-2A)、3/8-16UNC-2A(或0.375-16UNC-2A)（注：表中上行斜体数值单位为英寸，下行为毫米）




美制外螺纹（2A）常用规格极限尺寸表（细牙） 公称尺寸和每英寸牙数螺纹系列代号大径极限中径极限小径max螺胚直径最小最大最小最大最小最大
8-36UNF_0.1577 __0.1632 __0.1424 __0.1452 __0.1291 _3.65 3.67 (0.164-36)4.0056 4.1453 3.6170 3.6881 3.2791
10-32_0.1831 __0.1891 __0.1658 __0.1688 __0.1508 _4.24 4.27 (0.190-32)4.6507 4.8031 4.2113 4.2875 3.8303
12-28_0.2085 __0.2150 __0.1886 __0.1918 __0.1712 _4.82 4.85 (0.216-28)5.2959 5.4610 4.7904 4.8717 4.3485
1/4-28_0.2425 __0.2490 __0.2225 __0.2258 __0.2052 _5.69 5.71 (0.250-28)6.1595 6.3246 5.6515 5.7353 5.2121
5/16-24_0.3042 __0.3114 __0.2806 __0.2843 __0.2603 _7.17 7.20 (0.3175-24)7.7267 7.9096 7.1272 7.2212 6.6116
3/8-24_0.3667 __0.3739 __0.3430 __0.3468 __0.3228 _8.75 8.78 (0.375-24)9.3142 9.4971 8.7122 8.8087 8.1991
7/16-20_0.4281 __0.4362 __0.3995 __0.4037 __0.3749 _10.19 10.23 (0.4375-20)10.8737 11.0795 10.1473 10.2540 9.5225
1/2-20_0.4906 __0.4987 __0.4619 __0.4662 __0.4374 _11.78 11.82 (0.50-20)12.4612 12.6670 11.7323 11.8415 11.1100 9/16-18_0.5524 __0.5611 __0.5205 __0.5250 __0.4929 _13.27 13.31 (0.5625-18)14.0310 14.2519 13.2207 13.3350 12.5197
5/8-18_0.6149 __0.6236 __0.5828 __0.5875 __0.5554 _14.85 14.89 (0.625-18)15.6185 15.8394 14.8031 14.9225 14.1072
3/4-16_0.7391 __0.7485 __0.7029 __0.7079 __0.6718 _17.91 17.95 (0.750-16)18.7731 19.0119 17.8537 17.9807 17.0637
7/8-14_0.8631 __0.8734 __0.8216 __0.8270 __0.7858 _20.93 20.97 (0.875-14)21.9227 22.1844 20.8686 21.0058 19.9593 1"-12_0.9868 __0.9982 __0.9382 __0.9441 __0.8960 _23.90 23.95 (1.000-12)25.0647 25.3543 23.8303 23.9801 22.7584 1.螺胚直径指滚丝前的尺寸，数值为依经验公式计算而得，在实践中需验证。 2.标记示例：10-32UNF-2A(或0.190-32UNF-2A)、3/8-24UNF-2A(或0.375-24UNF-2A)





美制内螺纹（2B）常用规格极限尺寸表（粗牙） 公称尺寸和每英寸牙数螺纹系列代号小径极限中径极限大径min底孔直径最小最大最小最大最小最大
8-32UNC _0.1300 __0.1390 __0.1437 __0.1475 __0.1640 _3.40 3.50 (0.164-32)3.3020 3.5306 3.6500 3.7465 4.1656
10-24_0.1450 __0.1560 __0.1629 __0.1672 __0.1900 _3.75 3.90 (0.190-24)3.6830 3.9624 4.1377 4.2469 4.8260
12-24_0.1710 __0.1810 __0.1889 __0.1933 __0.2160 _4.40 4.55 (0.216-24)4.3434 4.5974 4.7981 4.9098 5.4864
1/4-20_0.1960 __0.2070 __0.2175 __0.2224 __0.2500 _5.05 5.20 (0.250-20)4.9784 5.2578 5.5245 5.6490 6.3500
5/16-18_0.2520 __0.2650 __0.2764 __0.2817 __0.3125 _6.45 6.60 (0.3175-18)6.4008 6.7310 7.0206 7.1552 7.9375
3/8-16_0.3070 __0.3210 __0.3344 __0.3401 __0.3750 _7.85 8.00 (0.375-16)7.7978 8.1534 8.4938 8.6385 9.5250
7/16-14_0.3600 __0.3760 __0.3911 __0.3972 __0.4375 _9.20 9.40 (0.4375-14)9.1440 9.5504 9.9339 10.0889 11.1125
1/2-13_0.4170 __0.4340 __0.4500 __0.4565 __0.5000 _10.65 10.90 (0.50-13)10.5918 11.0236 11.4300 11.5951 12.7000 9/16-12_0.4720 __0.4900 __0.5084 __0.5152 __0.5625 _12.05 12.30 (0.5625-12)11.9888 12.4460 12.9134 13.0861 14.2875
5/8-11_0.5270 __0.5460 __0.5660 __0.5732 __0.6250 _13.45 13.70 (0.625-11)13.3858 13.8684 14.3764 14.5593 15.8750
3/4-10_0.6420 __0.6630 __0.6850 __0.6927 __0.7500 _16.40 16.70 (0.750-10)16.3068 16.8402 17.3990 17.5946 19.0500
7/8-9_0.7550 __0.7780 __0.8028 __0.8110 __0.8750 _19.30 19.60 (0.875-9)19.1770