Standard Series Limits of Size­Unified and American Screw ...

1 Standard Series Limits of Size Unified and American Screw size and threads per inchSeries DesignationExternalInternalClassAllow anceMajor diameter limitsPitch diameter limitsMaxMinMinMaxMinToleranceMinor diameter ClassMinor dia. limitsPitch diameter limitsMinMaxMinMaxToleranceMajor diam .. : The following seven sizes have been standardized as between American , Canadian, and British military services or industry for purposes of attachment an instruments or accessory to a panel: 0 80 NF, 2 56 NC, 4 40 NC, 8 32 NC, 10 24 NC, and 10 32 NF, with 10 32 preferred over 10 24.

2 Standard Series Limits of Size Unified and American Screw Threads(cont.).Nominal size and threads per inchSeries DesignationExternalInternalClassAllow anceMajor diameter limitsPitch diameter limitsMaxMinMinMaxMinToleranceMinor diameter ClassMinor dia. limitsPitch diameter limitsMinMaxMinMaxToleranceMajor diam 20 UNC1A 2A3A .0011 .0011 .0000 ..2408 .2419 .2175 .2108 .2127 .2147 .. 28 UNF1A 2A .0000 ..2425 .2435 ..2268 ..0050 .0033 . 32 NEF 2A 3A ..2273 .0032 .0024 . 18 UNC1A 2A 3A ..3113 .3113 ..3026 .3038 .. 24 UNF1A ..2843 ..2806 . 32 NEF 2A 3A .0010 ..3065 ..0032 .0024 . 16 UNC1A 2A 3A.

3 0013 .0013 ..3737 .3750 .3595 .3643 .3656 ..3331 .3344 .3266 .3287 .3311 . 24 UNF1A 2A 3A .0011 .0011 ..3667 .3678 .3468 .3468 ..0057 .0038 . 32 NEF 2A 3A .0010 ..3690 ..0034 .0025 . 14 UNC1A 2A 3A .0014 ..4258 ..3850 ..0047 . 20 UNF1A 2A ..4281 .4294 ..4019 .0062 .0042 . 28 UNEF 2A 3A ..4310 .4132 ..0027 . 12 N 2A 3A .0016 ..4886 .4443 .. 13 UNC1A 2A .0015 ..4485 ..4435 .. Series Limits of Size Unified and American Screw Threads (cont).Nominal size and threads per inchSeries DesignationExternalInternalClassAllow anceMajor diameter limitsPitch diameter limitsMaxMinMinMaxMinToleranceMinor diameter ClassMinor dia.

4 LimitsPitch diameter limitsMinMaxMinMaxToleranceMajor diam 20 UNIF1A 2A 3A ..4987 .5000 .4906 .4919 .4662 .4675 .4619 ..0043 .0032 .4374 .4387 IB 2B 3B .446 .4460 .457 ..4675 .4675 .4731 .4717 .0042 .5000 .50001/2 28 UNEF 2A ..4935 .4757 .4768 .4720 .4740 .0037 .0028 .4551 .4562 2B 3B .461 .4610 ..4768 .4816 .4804 ..5000 9/16 12 UNC1A 2A 3A .0016 ..5609 .5625 .5437 .5495 .5511 .5068 .5084 .4990 .5016 .5045 .0078 .0052 .0039 .4587 .4587 .4603 IB 2B 3B .472 .472 .4720 ..5084 .5084 .5186 .5152 .5135 .0102 ..5625 .5625 .5625 9/16 18 UNF1A 2A 3A .0014 .0014 ..5611 ..5524 .5538.

5 5250 .5250 .5264 .5182 .5205 .5230 .0068 .0045 .0034 .4929 .4929 .4943 IB 2B 3B .502 .502 .5020 ..5264 .5264 .5353 .5323 .5308 ..0044 .5625 .5625 .5625 9/16 24 NEF2A ..51142B ..56255/8 11 UNC1A 2A 3A .0016 ..6113 .6129 ..5644 .5660 .5561 .5589 .5619 .0083 .0055 .0041 .5119 .5119 .5135 IB 28 3B ..5660 .5660 .5767 ..0107 .0072 .0054 .6250 .6250 .6250 5/8 12 N2A 3A .0016 .0000 ..6120 .6136 .5693 .5709 .5639 .5668 .0054 .0041 .5212 .5228 2B 3B ..5709 .5780 .5762 .0071 .0053 .6250 .6250 5/8 18 UNF1A 2A 3A .0014 ..6236 ..6149 .6163 .5875 .5875 .5889 .5805 .5828 .5854 .0070 .0047 .0035 .5554 .5554 .5568 IB 2B 3B.

6 5889 .5889 .5890 .5949 ..0060 ..6250 .6250 5/8 24 NEF 2A 3A ..6178 .5967 .5979 .5927 .5949 .0040 .0030 .5727 .57392B 3B ..5979 .6031 .6018 .0052 .0039 .6250 .6250 11/16 12N2A ..58532B ..687511/16 24 NEF 2A 3A .0012 ..6875 .6791 .6803 .6592 .6604 .6552 .6574 .0040 .0030 .6352 .6364 2B 3B ..6604 .6656 .6643 .0052 .0039 .6875 .6875 3/4 10 UNC1A 2A 3A .0018 .0018 ..7482 .7500 .7288 .7353 .7371 ..6832 .6850 .6744 .6773 .6806 ..0044 .6255 .6255 .6273 IB 2B3B ..6850 .6850 .6965 .6927 ..0077 ..7500 .7500 3/4 12 ..7500 .7369 .7386 .6942 .6959 .6887 .6918 .0055 .0041 .6461 .64782B .6959 .7031 .7013 .0072.

7 0054 .7500 .7500 3/4 16 UNF 1A 2A 3A ..7500 .7473 .7391 .7406 .7079 .7079 ..0075 .0050 .0038 .6718 .6718 .6733 IB2B 3B ..7094 .7094 .7192 .7159 .7143 .0098 .0065 .0049 .7500 .7500 .7500 3/4 20 UNEF 2A ..68872B ..750013/16 12 N2A 3A ..8108 .8125 .7994 ..7584 .7512 .7543 .0055 .0041 .7086 .7103 2B .7220 .740 .7329 .7584 .7584 .7656 .7638 .0072 .0054 .8125 .8125 13/16 16UN2A ..73582B ..8125 Standard Series Limits of Size Unified and American Screw Threads (cont).Nominal size and threads per inchSeries DesignationExternalInternalClassAllow anceMajor diameter limitsPitch diameter limitsMaxMinMinMaxMinToleranceMinor diameter ClassMinor dia.

8 LimitsPitch diameter limitsMinMaxMinMaxToleranceMajor diam 20 UNEF 2A 3A ..8125 .8044 .7800 .7767 .0033 ..0019 .0000 .8731 .8731 ..8592 .8611 ..8009 .8028 .7914 .7946 .7981 .0095 .0063 .0047 ..0082 .0061 . 12 .0000 .8733 .8750 .8619 .8636 .8192 .8209 .8137 .8168 .0055 .0041 ..0054 ..0016 .0000 .8734 .8734 ..8631 .8647 .8270 .8270 .8286 .8189 .8216 .8645 .0081 .0054 .0041 ..0070 .0053 . 16 .0000 .8735 .8750 .8641 .8656 .8329 .8344 .8280 .8308 .0049 .0036 ..0047 . 20 .0000 .8737 .8750 .8656 .8669 .8412 .8425 .8368 .8392 .0044 .0033 ..0043 . 12 .0000 .9358 ..9261 .8817 ..8793.

9 0057 .0041 .. 20 .0000 .9361 .9375 .9280 .9294 .9036 .9050 .8991 .9016 .0045 .0034 ..0044 ..0020 .0000 .9980 ..9755 .9830 .9850 ..9168 .9188 .9067 .9100 .9137 .0101 .0068 .0051 ..0088 .0066 ..9868 .9441 .9441 .9353 .9382 .0088 .0059 ..0076 .9886 .9459 .9415 .0044 . 16 .0000 ..9891 .9906 .9579 .9594 .9529 .9557 .0050 .0037 ..0049 .0000 .. 1/16 .0057 .0042 . 1/16 16 .0000 .0050 .0037 ..0049 1 18 .0047 .0036 ..0046 1/8 .0109 .0072 .0054 ..0094 .0071 1/8 8 .0069 .0052 ..0067 1/8 ..0060.

10 0078 . Series Limits of Size Unified and American Screw Threads (cont).Nominal size and threads per inchSeries DesignationExternalInternalClassAllow anceMajor diameter limitsPitch diameter limitsMaxMinMinMaxMinToleranceMinor diameter ClassMinor dia. limitsPitch diameter limitsMinMaxMinMaxToleranceMajor diam 1/8 1/8 3/16 18751 3/16 3/16 1/4 1/4 1/4 1/4 1/4 5/16 5/16 3/8 3/8 3/8 3/8 3/8 7/16 7/16 Series Limits of Self Unified and American Screw Threads (cont).Nominal size and threads per inchSeries DesignationExternalInternalClassAllow anceMajor diameter limitsPitch diameter limitsMaxMinMinMaxMinToleranceMinor diameter ClassMinor dia.