Feststellschraube

Feststellschraube is a small fastener used to fix or lock the position of an adjustable component in mechanical assemblies. It is typically a grub screw with an internal drive that tightens against a mating surface, such as a shaft, bore, or collar, so that friction holds the component in place after alignment. The screw’s contact end can be flat, conical, cup-shaped, or rounded to suit the mating surface and to minimize damage.

Common forms and characteristics

Feststellschrauben are commonly threaded in metric sizes (for example M3 to M12) and may feature different head types, most often hex socket or slotted head, depending on accessibility and torque requirements. The points of contact—cone, flat, or cup—determine how the load is distributed and how the part bears on the surface. Some variants employ locking features such as a nylon insert or prevailing-torque design to resist loosening under vibration, though not all applications require such features.

Applications

They are widely used to secure adjustable components in machinery, equipment, and instrumentation. Typical uses include locking gears, pulleys, or collars on shafts after proper alignment; securing optical mounts and measurement devices; and fixing slides or gibs in machine tools. In precision assemblies, Feststellschrauben allow repeatable re-positioning by restoring the same clamping point.

Installation notes

Surface cleanliness and proper seating are important to achieve reliable clamping. Select the correct point style for the mating surface, avoid excessive preload to prevent damage, and apply appropriate torque. In high-vibration environments, consider additional locking methods or coarse-thread alternatives as needed.