ASME B18.6.3 Type 1 Cross Recessed Undercut Flat

Dimensions of ASME B18.6.3 Type 1 Cross Recessed Undercut Flat Countersunk Head Machine Screws

Nominal Size or Basic Screw Diameter	Length, L	Head Diameter, A		Head Height, H		Recess Diameter, M	Recess Depth, T	Recess Width, N	Driver Size	Recess Penetration Gaging Depth		Protrusion Above Gaging Diameter, F		Gaging Diameter, G
Nominal Size or Basic Screw Diameter	Length, L	Max	Min	Max	Min	Recess Diameter, M	Recess Depth, T	Recess Width, N	Driver Size	Max	Min	Max	Min	Gaging Diameter, G
0	1/8	0.112	0.096	0.025	0.018	0.062	0.035	0.014	0	0.036	0.020	Note 4	Note 4	Note 4
1	1/8	0.137	0.120	0.031	0.023	0.070	0.043	0.015	0	0.044	0.028	Note 4	Note 4	Note 4
2	1/8	0.162	0.144	0.036	0.028	0.088	0.048	0.017	1	0.049	0.033	0.029	0.017	0.124
3	1/8	0.187	0.167	0.042	0.033	0.096	0.055	0.018	1	0.056	0.040	0.031	0.018	0.148
4	3/16	0.212	0.191	0.047	0.038	0.110	0.070	0.018	1	0.071	0.055	0.032	0.019	0.172
5	3/16	0.237	0.215	0.053	0.043	0.122	0.081	0.018	1	0.082	0.066	0.034	0.020	0.196
6	3/16	0.262	0.238	0.059	0.048	0.140	0.066	0.025	2	0.067	0.044	0.036	0.021	0.220
8	1/4	0.312	0.285	0.070	0.058	0.168	0.094	0.029	2	0.095	0.072	0.039	0.023	0.267
10	5/16	0.362	0.333	0.081	0.068	0.182	0.110	0.030	2	0.110	0.087	0.042	0.025	0.313
12	3/8	0.412	0.380	0.092	0.078	0.226	0.110	0.030	3	0.104	0.081	0.045	0.027	0.362
1/4	7/16	0.477	0.442	0.107	0.092	0.244	0.124	0.032	3	0.119	0.096	0.050	0.029	0.424
5/16	1/2	0.597	0.556	0.134	0.116	0.310	0.157	0.053	4	0.148	0.126	0.057	0.034	0.539
3/8	9/16	0.717	0.670	0.161	0.140	0.358	0.205	0.061	4	0.196	0.174	0.065	0.039	0.653
7/16	5/8	0.760	0.715	0.156	0.133	0.386	0.234	0.065	4	0.225	0.203	0.073	0.044	0.690
1/2	3/4	0.815	0.765	0.156	0.130	0.402	0.252	0.068	4	0.241	0.219	0.081	0.049	0.739

Notes :

Where specifying nominal size in decimals, zeros preceding the decimals and in the fourth decimal place shall be omitted.
Screws of these length and shorter shall have undercut heads.
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.
No practical to gage.