3M Zahnrad Riemenscheibe 20-60 Zähne AF-Typ Pulley - für 20mm Breite Zahnriemen

Tooth count determines your drive ratio and pitch diameter. A higher tooth count gives a larger pulley diameter, which increases belt speed at the same RPM or reduces motor RPM for a given output speed. For CNC and 3D printer axes, 20T–30T pulleys are most common on the motor side. Match your driven pulley tooth count to achieve your target speed or torque ratio.

A plain bore uses set screws alone to grip the shaft — suitable for moderate torque and unidirectional loads. Keyway bores (K3, K4, K5, K6, K8) include a machined slot that accepts a matching key on the shaft, providing positive torque transmission. The number after K indicates the key width in mm (e.g., K4 = 4mm key). Use keyway variants for reversing loads, high torque, or applications where shaft slip is unacceptable.

These pulleys are designed for standard 3M synchronous timing belts with a 3mm pitch and 20mm width. Ensure your belt is labeled 3M and is 20mm wide. Common belt designations include 3M-XXX-20 (where XXX is the belt length in mm). Do not use with 2M, 5M, or other pitch belts — tooth profiles are not interchangeable.

Yes. The aluminum alloy construction keeps rotational inertia low, which is beneficial for stepper and servo motors that require rapid acceleration and deceleration. The AF set-screw flange provides secure shaft retention at typical motor shaft speeds. For very high RPM applications, verify that your bore-to-shaft fit is within tolerance to minimize vibration.

Use a digital caliper to measure the outer diameter of your motor or drive shaft at the mounting point. Select the bore size that matches your shaft diameter exactly — for example, a 6.35mm bore for a 1/4-inch (6.35mm) shaft. If your shaft has a flat or keyway, choose the corresponding keyway bore variant (e.g., K3 for a 3mm key). A bore that is too large will cause runout and slippage even with set screws tightened.

Yes. These AF-type pulleys can be used on both the drive (motor) shaft and the driven shaft. When used as an idler, ensure the bore matches the idler shaft diameter and that the set screw is tightened to the manufacturer's recommended torque. For free-spinning idler applications, a bearing-bore pulley is typically more appropriate — these AF pulleys are designed for fixed-shaft mounting.

AF stands for "double flange with set screw." The two raised flanges on either side of the pulley groove act as physical guides that keep the timing belt centered on the pulley during operation. This eliminates the need for external belt guides or tensioners in most applications and prevents the belt from walking off the pulley under lateral load or misalignment.