Dimensions of ASME B18.6.3 Type 1A Cross Recessed Close Tolerance 100 Deg Flat Countersunk Head Machine Screw

Nominal Size or Baic Screw Diameter	Head Diameter, A		Head Height, H, Ref.	Recess Diameter, M, Ref.	Recess Depth, T, Ref.	Recess Width, N, Ref.	Driver Size	Recess Penetration Gaging Depth		Protrusion Above Gaging Diameter, F		Gaging Diameter, G
	Max	Min						Max	Min	Max	Min
4	0.212	0.188	0.049	0.110	0.070	0.029	1	0.068	0.052	0.025	0.019	0.167
6	0.262	0.235	0.060	0.148	0.077	0.041	2	0.071	0.053	0.028	0.021	0.214
8	0.312	0.282	0.072	0.162	0.092	0.041	2	0.086	0.068	0.031	0.023	0.261
10	0.362	0.329	0.083	0.178	0.107	0.041	2	0.101	0.083	0.034	0.026	0.307
1/4	0.477	0.437	0.110	0.240	0.126	0.056	3	0.114	0.096	0.040	0.031	0.415
5/16	0.597	0.550	0.138	0.310	0.163	0.085	4	0.145	0.127	0.047	0.037	0.526
3/8	0.717	0.662	0.165	0.336	0.187	0.085	4	0.170	0.152	0.053	0.042	0.638
7/16	0.837	0.774	0.193	0.360	0.208	0.086	4	0.194	0.176	0.060	0.047	0.750
1/2	0.957	0.887	0.221	0.386	0.239	0.086	4	0.222	0.204	0.066	0.053	0.862
9/16	1.077	1.000	0.249	0.418	0.271	0.086	4	0.253	0.235	0.073	0.058	0.974
5/8	1.197	1.112	0.276	0.488	0.256	0.097	5	0.228	0.207	0.080	0.063	1.086

Note :

• Where specifying nominal size in decimals, zeros preceding the decimals and in the fourth decimal place shall be omitted.
• Tabulated values determined from formula for maximum H in Appendix A.
• No tolerance for gaging diameter is given. If the gaging diameter of the gage used differs from tabulated value, the protrusion will be affected accordingly and the proper protusion values must be recalculated using the formulas.