4-40 x 1/8 Alloy Steel Button Head Socket Cap Screw is selected for socket-drive fastening where head projection, appearance, and bearing area all matter. The alloy steel construction is used in machinery repair where a rounded head and socket-drive access help keep service work straightforward.

Suitable assembly locations include automation equipment and conveyor assemblies where the compact head profile helps protect nearby moving components. The same head style is useful for equipment housings and assembly fixtures when the button head presents a clean bearing surface on visible hardware. Engineers often choose this style when a standard socket head cap screw would stand taller than the assembly layout allows.

When checking fit for the 4-40 thread and 1/8 in. length, the reference head diameter is 0.201-0.213 in. and the head height is 0.051-0.059 in. The nominal body diameter and hex-key information below support counterbore planning, socket access, and replacement matching.

Technical Highlights

• Material: Alloy Steel
• Thread Size: 4-40
• Length: 1/8 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.

Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.