(2000pcs) M4 Keps Nut for 4mm Bolts (Dia. 4mm)

The M4 Keps Nut (Pack of 2000 Pcs)—also referred to as a washer nut, captive tooth lock nut, or K-lock nut—is a highly efficient fastener engineered to combine a standard hex nut with a pre-assembled, free-spinning star lock washer. Designed for applications subject to continuous motion or mechanical shock, this single-piece hardware component eliminates the need to fiddle with separate lock washers during assembly, speeding up installation while guaranteeing secure joint retention.

How the Free-Spinning Lock Design Works

Unlike split lock washers that can bind or score the mating surface during tightening, the external tooth star washer on a Keps nut spins freely on a collar beneath the hex nut. As you torque down the nut, the internal threads engage smoothly without friction from the washer. Once fully seated, the hardened teeth of the star washer bite firmly into the mounting surface, creating mechanical resistance that prevents the nut from backing off under high-frequency operational vibrations.

Durable Zinc-Plated Steel

Manufactured from high-strength carbon steel and electro-galvanized with a bright protective zinc coating, these nuts offer dependable structural integrity and long-term resistance against rust, ambient moisture, and workshop fluids.

Common Applications

• 3D Printers & CNC Routers: Fastening frame components, stepper motor mounts, and enclosure brackets exposed to axis movement and vibration.

• Robotics & Electronics: Securing circuit board standoffs, chassis panels, and internal frame braces.

• Automotive & Small Engines: Fastening wiring harness brackets, accessory mounts, and lightweight body panels.

• General Workshop Fabrication: Any assembly requiring quick installation of a vibration-resistant threaded joint without loose secondary washers.

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