HTD-8M Timing Pulley 10T~20T for 25mm Belt Black 45# Steel AF Type Timing Pulley

The tooth count determines your drive ratio. Divide the driven pulley teeth by the driving pulley teeth to get the speed reduction ratio. For example, a 10T drive pulley paired with a 20T driven pulley gives a 2:1 reduction, halving speed and doubling torque. Choose a smaller tooth count on the motor side for more torque, or a larger count for higher output speed.

Measure your motor or gearbox output shaft diameter with a caliper. Select the bore that matches exactly — a bore that is too large will cause runout and vibration. If your shaft is metric (e.g., 10 mm, 12 mm), select the matching metric bore. For imperial shafts, the 12.7 mm bore option corresponds to 1/2 inch.

A keyway is recommended for any application with reversing direction, high torque, or where precise angular positioning is required. Without a keyway, the pulley is held by a set screw alone, which can slip under shock loads. Match the keyway width to the key already cut on your shaft — common sizes are 3 mm (for 10–12 mm shafts), 4 mm (12–17 mm shafts), 5 mm (14–22 mm shafts), 6 mm (18–28 mm shafts), and 8 mm (22–28 mm shafts). Confirm with your shaft specification.

Yes. The HTD-8M tooth profile is an industry-standard geometry. These pulleys are compatible with any HTD-8M timing belt that is 25 mm wide, regardless of brand, as long as the belt pitch matches (8 mm). Do not use with GT2, T5, T10, or other pitch belts — the tooth profiles are not interchangeable.

45# carbon steel (equivalent to AISI 1045) has a tensile strength of approximately 600–700 MPa, making it well-suited for medium-to-high torque synchronous drives. The black oxide finish provides mild corrosion resistance suitable for indoor workshop and light industrial environments. For outdoor or high-humidity applications, periodic light oiling of the bore and hub is recommended.

The hub width is 27 mm across all variants in this listing. Ensure your frame, bearing block, or motor mount has at least 27 mm of axial clearance for the pulley body, plus additional clearance for any flanges and fasteners. If space is tight, verify the outer diameter for your chosen tooth count before ordering — larger tooth counts have a proportionally larger pitch diameter.

Yes. HTD-8M pulleys are commonly used on CNC router axes, laser cutter gantries, and plasma table drives where the 8M pitch provides the torque capacity needed for heavier gantry masses. Pair with an appropriately rated HTD-8M belt and tensioner for best results. For lighter-duty CNC builds (small desktop routers), consider whether a smaller pitch such as 5M or 3M might offer better resolution.