Type B Screw Thread Specifications and Dimensions

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Thread Dimensions for Type B Self-tapping Screw Threads - ANSI B18.6.4

Basic Screw Diameter or Nominal Size		Threads Per Inch	D		d		P		S		L		Minimum Torsional Strength (Lb In) (Steel Screws Only)
			Major Diameter		Minor Diameter		Point Diameter		Point Taper Length		Minimum Practical Screw Length
			Max	Min	Max	Min	Max	Min	Max	Min	90° Heads	Csk Heads
2	.0860	32	.088	.082	.064	.060	.058	.054	.062	.047	5/32	3/16	4
3	.0990	28	.101	.095	.075	.071	.068	.064	.071	.054	3/16	7/32	9
4	.1120	24	.114	.108	.086	.082	.079	.074	.083	.063	3/16	1/4	13
5	.1250	20	.130	.123	.094	.090	.087	.082	.100	.075	7/32	9/32	18
6	.1380	20	.139	.132	.104	.099	.095	.089	.100	.075	1/4	9/32	24
7	.1510	19	.154	.147	.115	.109	.105	.099	.105	.079	1/4	5/16	30
8	.1640	18	.166	.159	.122	.116	.112	.106	.111	.083	9/32	11/32	39
10	.1900	16	.189	.182	.141	.135	.130	.123	.125	.094	5/16	3/8	56
12	.2160	14	.215	.208	.164	.157	.152	.145	.143	.107	11/32	7/16	88
1/4	.2500	14	.246	.237	.192	.185	.179	.171	.143	.107	3/8	1/2	142
5/16	.3125	12	.315	.306	.244	.236	.230	.222	.167	.125	15/32	19/32	290
3/8	.3750	12	.380	.371	.309	.299	.293	.285	.167	.125	17/32	11/16	590
Length Tolerance: Up to/including 3/4" = -.03, Over 3/4 to/including 1-1/2" = -.05, Over 1-1/2" = -.06
* Countersunk Bolts and Screws lengths are always measured from the top of the head

Applications For molded or through holes in thin metal, non ferrous castings, plastics or resin filled plywood. Material Steel: AISI 1016-1024 oe equivalent steel Heat Treatment Quenched in liquid and then tempered by reheating to 650°F minimum Surface Hardness Rockwell C45 Minimum Case Depth Nos. 4 thru 6 Dia. - .002-.007, Nos. 8 thru 12 dia. - .004 - .009, 1/4" and larger - .005 - .011 Core Hardness Rockwell C28 - C38 after tempering Plating See plating pages