Whitworth Fine Thread BS 84

British Standard Fine Thread Series (parallel, cylindrical).
BSW and BSF are the Thread selections for commercial screws and nuts. The Fine Thread, which is widespread in the Britisch machine tool industry, is superseded by the American UNF Thread.
The flank angle is 55°.

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Nominal Diameter	Major Diameter Inch	Major Diameter mm	Tapping Drill Size mm	TPI	Pitch mm
BSF 3/16"	0.1875	4.763	3.950	32	0.794
BSF 7/32"	0.2188	5.556	4.600	28	0.907
BSF 1/4"	0.2500	6.350	5.300	26	0.977
BSF 9/32"	0.2812	7.144	6.100	26	0.977
BSF 5/16"	0.3125	7.938	6.750	22	1.154
BSF 3/8"	0.3750	9.525	8.200	20	1.270
BSF 7/16"	0.4375	11.113	9.580	18	1.411
BSF 1/2"	0.5000	12.700	11.100	16	1.587
BSF 9/16"	0.5625	14.288	12.600	16	1.587
BSF 5/8"	0.6250	15.875	13.900	14	1.814
BSF 11/16"	0.6875	17.463	15.500	14	1.814
BSF 3/4"	0.7500	19.050	16.700	12	2.117
BSF 7/8"	0.8750	22.225	19.600	11	2.309
BSF 1"	1.0000	25.400	22.500	10	2.540
BSF 1 1/8"	1.1250	28.575	25.400	9	2.822
BSF 1 1/4"	1.2500	31.750	28.560	9	2.822
BSF 1 3/8"	1.3750	34.925	31.350	8	3.175
BSF 1 1/2"	1.5000	38.100	34.500	8	3.175
BSF 1 5/8"	1.6250	41.275	37.710	8	3.175
BSF 1 3/4"	1.7500	44.450	40.480	7	3.628
BSF 2"	2.0000	50.800	46.830	7	3.628
BSF 2 1/4"	2.2500	57.150	52.400	6	4.233
BSF 2 1/2"	2.5000	63.500	58.740	6	4.233
BSF 2 3/4"	2.7500	69.850	65.000	6	4.233
BSF 3"	3.0000	76.200	70.500	5	5.080
BSF 3 1/4"	3.2500	82.550	79.370	5	5.080
BSF 3 1/2"	3.5000	88.900	82.550	4.5	5.644
BSF 3 3/4"	3.7500	95.250	88.900	4.5	5.644
BSF 4"	4.0000	101.600	95.250	4.5	5.644
BSF 4 1/4"	4.2500	107.950	101.600	4	6.350
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