美制螺紋（2A）常用規(guī)格極限尺寸表
公稱尺寸和每英寸牙數(shù) 螺紋系列代號 大徑極限 中徑極限 小徑max 螺胚直徑
最小 最大 最小 最大 最小 最大
8-32 UNC 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