Shoulder Screws

Shoulder screws, also called shoulder bolts or stripper bolts, have a precision-ground unthreaded shoulder between the head and the threads. The smooth, accurately-sized shoulder acts as a bearing surface, shaft, or pivot, making these screws essential for rotating mechanisms, linkages, and precision tooling. We stock shoulder screws in alloy and stainless across the full size range.

How Shoulder Screws Work

The defining feature is the ground shoulder — a precise diameter and length that serves as a dowel or axle. Parts rotate or slide on the shoulder while the threaded end anchors the screw. This lets a shoulder screw function as a fastener and a precision pivot in one part, common in dies, jigs, pulleys, and moving assemblies.

Key Dimensions

Shoulder screws are specified by shoulder diameter (the functional bearing surface) and shoulder length, not by the thread size — the thread is always smaller than the shoulder. When ordering, the shoulder diameter is the critical fit dimension. The thread is sized proportionally (e.g., a 3/8" shoulder uses a 5/16-18 thread).

Materials

Alloy steel: through-hardened with a black oxide finish and ground shoulder, the standard for durability and precise fit. 18-8 stainless: corrosion resistance where the mechanism is exposed.

Dimensional Standards

Inch shoulder screws conform to ASME B18.3; metric versions to ISO 7379 / DIN 9841. All use an internal hex (socket) drive.

Selecting the Right Shoulder Screw

Specify by shoulder diameter and length for your bearing or pivot fit, not thread size. Choose alloy steel for hardened wear surfaces, stainless for corrosion. Ream the mating hole to suit the shoulder fit (clearance for rotation, press for fixed). Confirm the thread matches the tapped hole and select the correct hex key.

Use the filters to narrow by shoulder diameter, length, and material.