4-40 x 3/4 Brass Button Head Socket Cap Screw is selected for exposed fastening points where appearance, machinability, and internal hex access matter more than high-strength fastening. This head style is a practical choice where the fastener should remain accessible while presenting a compact rounded profile. Because brass is non-ferrous, it can be useful in selected electrical, instrument, and laboratory applications where magnetic response is undesirable.

Appropriate uses include architectural hardware and commercial brass components, where the rounded head provides a finished appearance on visible covers and trim. It can also fit maintenance work and assembly operations, where the exact thread and length help match drawings, repair lists, and existing brass hardware. The internal hex drive supports socket-key installation in compact equipment without relying on an external wrenching surface.

For the 4-40 thread and 3/4 in. length, the reference head diameter is 0.201-0.213 in. and the head height is 0.051-0.059 in. Use the verified dimensions below when checking head projection, socket access, and replacement fit.

Technical Highlights

• Material: Brass
• Thread Size: 4-40
• Length: 3/4 in.
• Nominal Body Diameter: #4 (.112 in.)
• Head Diameter: 0.201-0.213 in.
• Head Height: 0.051-0.059 in.
• Hex-Key Size: 1/16 in.
• Drive Type: Internal Hex

Reference dimensions may vary slightly by manufacturer.