Precision Shoulder Screws

Precision Shoulder Screws, also known as shoulder bolts, are fasteners with an unthreaded cylindrical section, or shoulder, between threads and screwhead. The shoulder is larger in diameter than the threaded section and provides an axis around which close-fitting moving parts operate.

Precision shoulder screws are available with an undercut shoulder where the diameter of the shoulder can be as small as the minor diameter of the threads. Precision shoulder screws are identified by the diameter and the length of the shoulder.

Precision shoulder screws can be produced with a slotted or hex socket head. Precision shoulder screws differ from standard shoulder screws in that they have very tight dimensional tolerances. Precision shoulder screws are typically available in stainless steel but can also be made from alloy steel and brass.

Notes:
1. The shoulder diameter is the basis for the determination and callout of the screw size.

2. Screw threads are Class 4g6g.

3. Concentricity: The shoulder and thread pitch diameter shall be concentric within 0.10 mm full indicator movement (FIM), determined at a distance of 4.75 mm from the face of the shoulder. Concentricity, parallelism, bow, and squareness of the face of the shoulder with the axis of the thread shall be within 0.125mm FIM per 25.0mm of shoulder length, with a maximum of 0.70 mm when the shoulder face is firmly seated against a threaded bushing and deviation is checked on the shoulder at a distance of 2F from the underside of the head. The thread in the bushing shall be basic size, and the bushing O.D. and ends shall be concentric and square with the axis of the thread respectively.

We carry both metric and inch standard sizes.