BS 1981 Raised Cheese Head Screws

Nom.Size of Screw	Basic Dia. D	Threads per Inch		Dia. of Head A		Depth of Head B		Width of Slot H		Depth of Slot J
Nom.Size of Screw	Basic Dia. D	UNC	UNF	Max.	Min.	Max.	Min.	Max.	Min.	Depth of Slot J
BS 1981 - 4	0.112	40	...	0.183	0.166	0.107	0.088	0.039	0.031	0.042
BS 1981 - 6	0.138	32	...	0.226	0.208	0.132	0.111	0.048	0.039	0.053
BS 1981 - 8	0.164	32	...	0.27	0.25	0.156	0.133	0.054	0.045	0.063
BS 1981 - 10	0.19	24 c	32	0.313	0.292	0.18	0.156	0.06	0.05	0.074
BS 1981 - 1⁄4	0.25	20	28	0.414	0.389	0.237	0.207	0.075	0.064	0.098
BS 1981 - 5⁄16	0.3125	18	24	0.518	0.49	0.295	0.262	0.084	0.072	0.124
BS 1981 - 3⁄8	0.375	16	24	0.622	0.59	0.355	0.315	0.094	0.081	0.149
BS 1981 - 7⁄16	0.4375	14	20	0.625	0.589	0.368	0.321	0.094	0.081	0.153
BS 1981 - 1⁄2	0.5	13	20	0.75	0.71	0.412	0.362	0.106	0.091	0.171
BS 1981 - 5⁄8	0.625	11	18	0.875	0.827	0.521	0.461	0.133	0.116	0.217
BS 1981 - 3⁄4	0.75	10	16	1	0.945	0.612	0.542	0.149	0.131	0.254
a All dimensions, except J, given for the No. 4 to 38-inch sizes, incl., also apply to all the 80° Raised Countersunk Head Screws given in the Standard. b Also available with recessed heads. c Non-preferred. d By arrangement may also be 0.468.