5M Timing Belt Pulley 15T-60T keyway Bore AF-type 16/21mm Belt Synchronous Wheel

The tooth count determines your drive ratio. Divide the driven pulley tooth count by the driving pulley tooth count to get the speed reduction ratio. For example, a 15T driver paired with a 60T driven pulley gives a 4:1 reduction. If you need 1:1 (no speed change), use matching tooth counts on both pulleys. For CNC axes, 20T is a common starting point with standard 5M belts.

AF-type refers to a bore with a machined keyway slot and a set-screw (grub screw) collar. The keyway accepts a matching key on the shaft, preventing the pulley from rotating independently of the shaft under torque. This is more secure than a plain bore with set-screw alone, making it the preferred choice for applications with reversing loads or high acceleration.

Match the bore diameter to your motor shaft diameter exactly. Common stepper motor shaft sizes are 5 mm, 6.35 mm (1/4 in), and 8 mm. Servo motors often use 8 mm, 10 mm, or 12 mm shafts. Also confirm the keyway dimensions match your shaft's key: the bore width label in each variant lists both the bore diameter and the keyway size (e.g., "8mm (3×1.4mm)").

Yes. The 5M pitch (5 mm tooth-to-tooth spacing) used on this pulley is the same as the HTD-5M standard. It will mesh correctly with any HTD-5M synchronous belt of the matching width (16 mm or 21 mm). Ensure your belt width matches the variant you select for full tooth engagement.

It is not recommended. Using a narrower belt on a wider pulley reduces the contact area and load capacity, and the belt may track unevenly between the flanges. Always match the belt width to the pulley's belt-width specification for reliable, long-term operation.

Aluminum alloy pulleys are well-suited for light-to-medium duty applications such as CNC routers, 3D printers, laser cutters, and small robotic arms. They offer a favorable strength-to-weight ratio and resist corrosion without surface treatment. For heavy industrial loads or continuous high-torque environments, a steel pulley would be more appropriate. If you are unsure, contact us to confirm suitability for your specific load requirements.

The set screw is included with the pulley. A matching shaft key is not always included — please confirm at checkout or contact us before ordering if you need the key supplied separately. Standard key stock for these bore sizes is widely available at hardware and engineering suppliers.