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Sheet Metal Self Threading ANSI Screws Dimensions for B and BP Thread

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Sheet Metal Self Threading ANSI Screws Dimensions for B and BP Thread Forming and BF and BT Thread Cutting Tapping Screws per. ANSI B18.6.4 and ASTM F593

Type B: Spaced-thread screw with a blunt point with pitches generally somewhat finer than Type A. Used for thin metal, non-ferrous castings, plastics, resin-impregnated plywood, and asbestos compositions.

Type BP: Spaced-thread screw, the same as Type B but having a conical point extending beyond incomplete entering threads. Used for piercing fabrics or in assemblies where holes are misaligned.

Types BF and BT: Thread-cutting screws with spaced threads as in Type B, with blunt points, and one or more cutting grooves. Used in plastics, asbestos, and other similar compositions.

THREAD FORMING TYPES B AND BP
Nominal Sizea - Dia.	Thds per Inchb	Major Diameter		Minor Diameter
0 - 0.0600	48	0.060	0.054	0.036	0.033
1 - 0.0730	42	0.075	0.069	0.049	0.046
2 - 0.0860	32	0.088	0.082	0.064	0.060
3 - 0.0990	28	0.101	0.095	0.075	0.071
4 - 0.1120	24	0.114	0.108	0.086	0.082
5 - 0.1250	20	0.130	0.123	0.094	0.090
6 - 0.1380	20	0.139	0.132	0.104	0.099
7 - 0.1510	19	0.154	0.147	0.115	0.109
8 - 0.1640	18	0.166	0.159	0.122	0.116
10 - 0.1900	16	0.189	0.182	0.141	0.135
12 - 0.2160	14	0.215	0.208	0.164	0.157
1⁄4 - 0.2500	14	0.246	0.237	0.192	0.185
5⁄16 - 0.3125	12	0.315	0.306	0.244	0.236
3⁄8 - 0.3750	12	0.380	0.371	0.309	0.299
7⁄16 - 0.4375	10	0.440	0.429	0.359	0.349
1⁄2 - 0.5000	10	0.504	0.493	0.423	0.413

^a Where specifying nominal size in decimals, zeros preceding decimal and in the fourth decimal place shall be omitted.

^b The width of flat at crest of thread shall not exceed 0.004 inch for sizes up to No. 8, inclusive, and 0.006 inch for larger sizes.

^c Point diameters specified apply to screw threads before roll threading.

^d Points of screws are tapered and fluted or slotted. The flute on Type BT screws has an included angle of 90 to 95 degrees and the thread cutting edge is located above the axis of the screw. Flutes and slots extend through first full form thread beyond taper except for Type BF screw on which tapered threads may be complete at manufacturer's option and flutes may be one pitch short of first full form thread.

THREAD CUTTING TYPES BF AND BTd
Nominal Sizea - Dia.	Thds / Inchb	D		d
		Major Diameter		Minor Diameter
		Max	Min	Max	Min
0 - 0.0600	48	0.060	0.054	0.036	0.033
1 - 0.0730	42	0.075	0.069	0.049	0.046
2 - 0.0860	32	0.088	0.082	0.064	0.060
3 - 0.0990	28	0.101	0.095	0.075	0.071
4 - 0.1120	24	0.114	0.108	0.086	0.082
5 - 0.1250	20	0.130	0.123	0.094	0.090
6 - 0.1380	20	0.139	0.132	0.104	0.099
7 - 0.1510	19	0.154	0.147	0.115	0.109
8 - 0.1640	18	0.166	0.159	0.122	0.116
10 - 0.1900	16	0.189	0.182	0.141	0.135
12 - 0.2160	14	0.215	0.208	0.164	0.157
1⁄4 - 0.2500	14	0.246	0.237	0.192	0.185
5⁄16 - 0.3125	12	0.315	0.306	0.244	0.236
3⁄8 - 0.3750	12	0.380	0.371	0.309	0.299
7⁄16 - 0.4375	10	0.440	0.429	0.359	0.349
1⁄2 - 0.5000	10	0.504	0.493	0.423	0.413

All dimensions are in inches.

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