Technical Information

SCREW THREAD DATA CHARTS

UNEF Screw Threads per ANSI B1.1

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UNEF Screw Threads per ANSI B1.1
UNEF = Unified National Extra Fine
Nominal Diameter	Major Diameter Inch	Major Diameter mm	Tapping Drill Size mm	TPI	Pitch mm
#12 - 32 UNEF	0.216	5.486	4.80	32	0.794
1/4" - 32 UNEF	0.250	6.350	5.70	32	0.794
5/16" - 32 UNEF	0.313	7.938	7.25	32	0.794
3/8" - 32 UNEF	0.375	9.525	8.85	32	0.794
7/16" - 28 UNEF	0.438	11.112	10.35	28	0.907
1/2" - 28 UNEF	0.500	12.700	11.80	28	0.907
9/16" - 24 UNEF	0.563	14.288	13.40	24	1.058
5/8" - 24 UNEF	0.625	15.875	15.00	24	1.058
11/16" - 24 UNEF	0.688	17.462	16.60	24	1.058
3/4" - 20 UNEF	0.750	19.050	18.00	20	1.270
13/16" - 20 UNEF	0.813	20.638	19.60	20	1.270
7/8" - 20 UNEF	0.875	22.225	21.15	20	1.270
15/16" - 20 UNEF	0.938	23.812	22.70	20	1.270
1" - 20 UNEF	1.000	25.400	24.30	20	1.270
1-1/16" - 18 UNEF	1.063	26.988	25.80	18	1.411
1-1/8" - 18 UNEF	1.125	28.575	27.35	18	1.411
1-1/4" - 18 UNEF	1.250	31.750	30.55	18	1.411
1-5/16" - 18 UNEF	1.313	33.338	32.10	18	1.411
1-3/8" - 18 UNEF	1.375	34.925	33.70	18	1.411
1-7/16" - 18 UNEF	1.438	36.512	35.30	18	1.411
1-1/2" - 18 UNEF	1.500	38.100	36.90	18	1.411
1-9/16" - 18 UNEF	1.563	39.688	38.55	18	1.411
1-5/8" - 18 UNEF	1.625	41.275	40.10	18	1.411
1-11/16" - 18 UNEF	1.688	42.862	41.60	18	1.411
UNEF Thread

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