ASME B18.6.3 Type 1 Cross Recessed Indented Hex Washer

Dimensions of ASME B18.6.3 Type 1 Cross Recessed Indented Hex Washer Head Machine Screws

Nominal Size or Basic Screw Diameter	Width Across Flats, A		Across Corners, W, Min	Head Height, H		Washers Diameter, B		Washers Thickness, U		Recess Diameter, M	Recess Depth, T	Recess Width, N	Driver Size	Recess Penetrations Gaging Depth		Protrusion Beyond Gaging Ring, F, Min
Nominal Size or Basic Screw Diameter	Max	Min	Across Corners, W, Min	Max	Min	Max	Min	Max	Min	Recess Diameter, M	Recess Depth, T	Recess Width, N	Driver Size	Max	Min	Protrusion Beyond Gaging Ring, F, Min
4	0.188	0.181	0.202	0.060	0.049	0.243	0.225	0.019	0.011	0.097	0.065	0.017	1	0.067	0.049	0.029
5	0.188	0.181	0.202	0.070	0.058	0.260	0.240	0.025	0.015	0.105	0.074	0.017	1	0.076	0.058	0.035
6	0.250	0.244	0.272	0.093	0.080	0.328	0.302	0.025	0.015	0.148	0.088	0.026	2	0.089	0.064	0.048
8	0.250	0.244	0.272	0.110	0.096	0.348	0.322	0.031	0.019	0.168	0.114	0.029	2	0.115	0.090	0.058
10	0.312	0.305	0.340	0.120	0.105	0.414	0.384	0.031	0.019	0.178	0.126	0.029	2	0.127	0.102	0.063
12	0.312	0.305	0.340	0.155	0.139	0.432	0.398	0.039	0.022	0.247	0.157	0.033	3	0.152	0.127	0.083
1/4	0.375	0.367	0.409	0.190	0.172	0.520	0.480	0.050	0.030	0.277	0.191	0.034	3	0.186	0.161	0.103

Notes :

Fillet Radius R at junction of sides of hex and top of washers shall not exceed 0.15 times the basic screw diameter.
A slight rounding of all edges and corners of the hex surfaces shall be permissible.
Where specifying nominal size in decimals, zeros preceding the decimal and in the fourth decimal place shall be omitted.
Dimensions across flats and across corners of the head shall be measured at the point of maximum metal. Taper of sides of hex (angle between one side and the axis) shall not exceed 2 deg or 0.004 in., whichever is greater, the specified width across flats being the large dimensions.
The rounding due to lack of fill on all six corners of the head shall be reasonably uniform and the width across corners of the head shall be such that when a sharp ring having an inside diameter equal to the specified minimum width across corners is placed on the top and bottom of the head, the head shall protrude by an amount equal to, or greater than the F value tabulated.
The recess depths and penetrations given are intended to include the depth of the indentation. Due to possible variations in the indentation depths, there could be variations in these dimensions. In these cases, the requirements are to be as agreed upon between the manufacturer and his customer.