American National Special
(Unified Special)

Historic American National Standards Institute-American Bearing Manufacturers Association threads for bearings Have been since adapted within Unified Inch Screw Thread Form (ANSI/ASME B1.1) identified as ‘UNS’.



Recommended Shaft/Spindle Thread Dimensions

Threads Major Dia Pitch Dia Minor Dia
Thread Size Per Inch Max Min Max Min Max
.391 - 32 32 0.3910 0.3856 0.3707 0.3681 0.3527
.469 - 32 32 0.4690 0.4636 0.4487 0.4461 0.4307
.586 - 32 32 0.5860 0.5806 0.5657 0.5627 0.5477
.664 - 32 32 0.6640 0.6586 0.6437 0.6407 0.6257
.781 - 32 32 0.7810 0.7756 0.7607 0.7573 0.7427
.969 - 32 32 0.9690 0.9636 0.9487 0.9453 0.9307
1.173 - 18 18 1.1730 1.1648 1.1369 1.1329 1.1048
1.312 - 18 18 1.3120 1.3038 1.2764 1.2724 1.2438
1.376 - 18 18 1.3760 1.3678 1.3399 1.3359 1.3078
1.563 - 18 18 1.5630 1.5548 1.5269 1.5224 1.4948
1.767 - 18 18 1.7670 1.7588 1.7309 1.7264 1.6988
1.967 - 18 18 1.9670 1.9588 1.9309 1.9264 1.8988
2.157 - 18 18 2.1570 2.1488 2.1209 2.1158 2.0888
2.204 - 18 18 2.2040 2.1958 2.1679 2.1628 2.1358
2.360 - 18 18 2.3600 2.3518 2.3239 2.3188 2.2918
2.407 - 18 18 2.4070 2.3988 2.3709 2.3658 2.3388
2.548 - 18 18 2.5480 2.5398 2.5119 2.5068 2.4798
2.626 - 18 18 2.6260 2.6178 2.5899 2.5848 2.5578
2.751 - 18 18 2.7510 2.7428 2.7149 2.7098 2.6828
2.933 - 12 12 2.9330 2.9218 2.8789 2.8735 2.8308
3.137 - 12 12 3.1370 3.1258 3.0829 3.0770 3.0348
3.340 - 12 12 3.3400 3.3288 3.2859 3.2800 3.2378
3.527 - 12 12 3.5270 3.5158 3.4729 3.4655 3.4248
3.730 - 12 12 3.7300 3.7188 3.6759 3.6685 3.6278
3.918 - 12 12 3.9180 3.9068 3.8639 3.8565 3.8158
4.122 - 12 12 4.1220 4.1108 4.0679 4.0596 4.0198
4.325 - 12 12 4.3250 4.3138 4.2709 4.2626 4.2228
4.716 - 12 12 4.7160 4.7048 4.6619 4.6536 4.6138
4.778 - 12 12 4.7780 4.7668 4.7239 4.7156 4.6758
5.106 - 12 12 5.1060 5.0948 5.0519 5.0436 5.0038
5.185 - 12 12 5.1850 5.1738 5.1309 5.1226 5.0828
5.497 - 12 12 5.4970 5.4858 5.4429 5.4346 5.3948
5.622 - 12 12 5.6220 5.6108 5.5679 5.5596 5.5198
5.888 - 12 12 5.8880 5.8768 5.8339 5.8256 5.7858
6.097 - 8 8 6.0970 6.0818 6.0158 6.0067 5.9436
6.284 - 8 8 6.2840 6.2688 6.2028 6.1937 6.1306
6.503 - 8 8 6.5030 6.4878 6.4218 6.4127 6.3496
6.659 - 8 8 6.6590 6.6438 6.5778 6.5687 6.5056
6.925 - 8 8 6.9250 6.9098 6.8438 6.8347 6.7716
7.066 - 8 8 7.0660 7.0508 6.9848 6.9757 6.9126
7.331 - 8 8 7.3310 7.3158 7.2498 7.2407 7.1776
7.472 - 8 8 7.4720 7.4568 7.3908 7.3817 7.3186
7.753 - 8 8 7.7530 7.7378 7.6718 7.6627 7.5996
7.847 - 8 8 7.8470 7.8318 7.7658 7.7544 7.6936
8.191 - 8 8 8.1910 8.1758 8.1098 8.0977 8.0376
8.628 - 8 8 8.6280 8.6128 8.5468 8.5347 8.4746
9.442 - 6 6 9.4420 9.4218 9.3337 9.3213 9.2375
10.192 - 6 6 10.1920 10.1718 10.0837 10.0707 9.9875
11.004 - 6 6 11.0040 10.9838 10.8957 10.8827 10.7995
11.785 - 6 6 11.7850 11.7648 11.6767 11.6637 11.5805
11.973 - 6 6 11.9730 11.9528 11.8647 11.8517 11.7685
12.562 - 6 6 12.5620 12.5418 12.4537 12.4402 12.3575
12.942 - 6 6 12.9420 12.9218 12.8337 12.8202 12.7375
13.723 - 6 6 13.7230 13.7028 13.6147 13.6012 13.5185

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