ASME B18.6.3 Slotted Undercut Flat Countersunk – Adfast Components

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Explore Adfast Components for precision-engineered fasteners, offering hot & cold forged solutions with metric sizes from M3 to M100 for diverse industrial needs.

materials

Carbon Steel

Alloy Steel

Stainless Steel

Super Alloys

Non Ferrous Metal & Alloys

High Performance Nickel Alloys

Copper Alloys

Technical

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Standard

Weight

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Threads
Contact

Home
About
Product
Product

Adfast Components offers precision-engineered hot and cold forged fasteners ranging from M3 to M100, ensuring superior strength and reliability. Designed to meet diverse industrial standards, our components guarantee durability and performance.

Precision Components

Pumps & Valves

Automobile

Customised

Electronic

Medical

Contract Manufacturing

3D Printing & Additive Manufacturing

Fastener

Bolts

Coated Fasteners

Washer

Stud Bolts

Nuts

Screws
Resources
Resources

Explore Adfast Components for precision-engineered fasteners, offering hot & cold forged solutions with metric sizes from M3 to M100 for diverse industrial needs.

materials

Carbon Steel

Alloy Steel

Stainless Steel

Super Alloys

Non Ferrous Metal & Alloys

High Performance Nickel Alloys

Copper Alloys

Technical

Specification

Standard

Weight

Applications

Threads
Contact

ASME B18.6.3 Slotted Undercut Flat Countersunk

Dimensions of ASME B18.6.3 Slotted Undercut Flat Countersunk Head Machine Screws

Nominal Size or Basic Screw Diameter	Length, L	Head Diameter, A		Head Height, H		Slot Width, J		Slot Depth, T		Protrusion Above Gaging Diameter, F		Gaging Diameter, G
Nominal Size or Basic Screw Diameter	Length, L	Max	Min	Max	Min	Max	Min	Max	Min	Max	Min	Gaging Diameter, G
0	1/8	0.112	0.096	0.025	0.018	0.023	0.016	0.011	0.007	Note 4	Note 4	Note 4
1	1/8	0.137	0.120	0.031	0.023	0.026	0.019	0.014	0.009	Note 4	Note 4	Note 4
2	1/8	0.162	0.144	0.036	0.028	0.031	0.023	0.016	0.011	0.029	0.017	0.124
3	1/8	0.187	0.167	0.042	0.033	0.035	0.027	0.019	0.012	0.031	0.018	0.148
4	3/16	0.212	0.191	0.047	0.038	0.039	0.031	0.022	0.014	0.032	0.019	0.172
5	3/16	0.237	0.215	0.053	0.043	0.043	0.035	0.024	0.016	0.034	0.020	0.196
6	3/16	0.262	0.238	0.059	0.048	0.048	0.039	0.027	0.017	0.036	0.021	0.220
8	1/4	0.312	0.285	0.070	0.058	0.054	0.045	0.032	0.021	0.039	0.023	0.267
10	5/16	0.362	0.333	0.081	0.068	0.060	0.050	0.037	0.024	0.042	0.025	0.313
12	3/8	0.412	0.380	0.092	0.078	0.067	0.056	0.043	0.028	0.045	0.027	0.362
1/4	7/16	0.477	0.442	0.107	0.092	0.075	0.064	0.050	0.032	0.050	0.029	0.424
5/16	1/2	0.597	0.556	0.134	0.116	0.084	0.072	0.062	0.041	0.057	0.034	0.539
3/8	9/16	0.717	0.670	0.161	0.140	0.094	0.081	0.075	0.049	0.065	0.039	0.653
7/16	5/8	0.760	0.715	0.156	0.133	0.094	0.081	0.072	0.045	0.073	0.044	0.690
1/2	3/4	0.815	0.765	0.156	0.130	0.106	0.091	0.072	0.046	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 lengths and shorter are undercut. Screws of longer lengths shall have head heights.
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.
Not practical to gage.