Shafts, Couplings and Hubs

Shafts, couplings, and hubs are essential mechanical components that transmit motion, connect elements, and ensure precise centering in your projects. This category covers a wide range of parts from linear motion shafts to torque-transmitting couplings and hubs that attach gears or pulleys to motor shafts. Whether you are building a 3D printer, CNC router, robotic arm, or automation system, you will find these components offered in various materials, tolerances, and sizes.

Shafts

Shafts form the backbone of linear motion systems. They are typically made of induction-hardened chrome-plated steel (linear shaft), stainless steel, or carbon steel. Depending on your application, you can choose from plain shafts, threaded shafts, trapezoidal lead screws, or ball screws. Diameters (commonly 8 mm, 10 mm, 12 mm, 16 mm, 20 mm) and length tolerances are critical for compatibility with linear bearings and bushings. In high-speed or precision positioning systems, pay close attention to surface hardness (HRC) and straightness tolerance.

Couplings

Couplings connect a motor shaft to a lead screw, encoder, or another shaft, transmitting torque while accommodating axial, radial, and angular misalignments. Key types include: rigid couplings with high torque capacity but low misalignment tolerance; jaw-type couplings that absorb shock and vibration; bellows couplings for applications requiring low backlash; and elastomeric couplings that provide flexible connections. When selecting a coupling, you must match the rated torque, maximum speed, shaft end diameters, and allowable misalignment values. A common mistake is choosing a coupling based solely on shaft diameter while ignoring torque and alignment requirements.

Hubs

Hubs fix gears, pulleys, encoder wheels and other components onto a motor or shaft. They use set-screw, clamping, or flange mounting methods. Usually manufactured from aluminum or steel, these parts are designed to fit various shaft and bore diameters. In stepper motor applications, clamping hubs used as adapters between a flexible coupling and the motor shaft are valued for their ease of installation and zero backlash. To prevent slippage during torque transfer, consider clamping force and material strength when selecting the right hub.

When matching components for your project, you need to evaluate factors such as diameter compatibility between shaft, coupling and hub, operating environment (temperature, humidity, chemicals), speed, and lateral loads. Making the right choice extends system life and ensures precise positioning and repeatability.