Holo-krome 08139 Shoulder Screw 3/4 in Alloy Steel Hex Socket

Product Description

The HOLO-KROME 08139 is an alloy steel shoulder screw designed for precision fastening applications that require a close-tolerance cylindrical shoulder to serve as a shaft, pivot, or guide pin. The shoulder measures 0.75 inches in diameter and 3.25 inches in length, giving it a 4.625-inch overall length. The threaded portion is 5/8-11 UNC with a 0.875-inch thread length. Drive engagement is through a 3/8-inch hex socket in a rounded head measuring 1 inch in diameter and 0.5 inches tall. The uncoated finish is standard for industrial assembly environments. This fastener is installed by maintenance technicians, millwrights, and mechanical assemblers working on jigs, fixtures, linkages, or precision machinery.

Shoulder screws of this type are used in applications where a hardened, ground shoulder must provide a bearing surface or act as a positional locator. Common install scenarios include die sets, fixture plates, conveyor components, robotic linkages, and motion-control assemblies. The 5/8-11 thread and grade 8 alloy steel construction provide high tensile strength suitable for heavy-duty mechanical assemblies. This screw is sold individually and suits both production and maintenance repair operations where exact shoulder geometry is critical to function.

Key Features

• 3/4-inch shoulder diameter and 3-1/4-inch shoulder length for precision locating and bearing applications
• Grade 8 alloy steel construction for high tensile and shear strength
• 5/8-11 UNC thread with 7/8-inch thread length meets ASME B18.3 and ASME B1.1 standards
• 3/8-inch hex socket drive for standard Allen wrench or hex bit installation
• Uncoated finish suitable for use with standard lubricants or thread lockers
• Rounded head with 1-inch diameter and 1/2-inch height provides a low-profile clamping surface

Compatibility

Designed as an OEM-style shoulder screw for use in precision mechanical assemblies, fixtures, and machinery where a 3/4-inch shoulder diameter and 5/8-11 threaded end are required per ASME B18.3 dimensional standards.

Installation Notes

Installation requires a 3/8-inch hex key or hex socket driver. Ensure the mating bore is sized to provide the appropriate clearance or press fit for the shoulder diameter before installation. De-energize and lock out any machinery before replacing or installing shoulder screws in mechanical assemblies. Do not use impact tools on hex socket head fasteners unless specifically rated for that application.