HTD-5M 15T-80T Timing Belt Pulley With Step/Keyway, Bore 8-25mm Teeth Width 16mm

The tooth count determines your drive ratio. Divide the driven pulley teeth by the driving pulley teeth to get the ratio. For example, a 20T driver paired with a 40T driven pulley gives a 2:1 reduction. Smaller tooth counts (15T–25T) are common on motor shafts for speed reduction; larger counts (40T–80T) are used on the driven axis or where higher torque is needed at lower RPM.

Keyway size is determined by your shaft diameter and the key standard used in your application. Common pairings: 8–10mm bore → 3×1.4mm key; 10–12mm bore → 4×1.8mm key; 12–17mm bore → 5×2.3mm key; 17–22mm bore → 6×2.8mm key; 22–25mm bore → 8×3.3mm key. Always verify against your shaft's existing keyway slot dimensions before ordering.

These pulleys have a 16mm teeth width, which is compatible with HTD 5M belts that are 15mm or 16mm wide. Using a narrower belt (e.g., 9mm or 10mm) on a 16mm pulley is possible but reduces load capacity. Do not use belts wider than the pulley teeth width.

Yes. Aluminum alloy HTD-5M pulleys with keyway are widely used in hobby and light-industrial CNC routers for X/Y/Z axis drives. The HTD tooth profile distributes load across multiple teeth, and the keyway prevents shaft slip. For heavy-duty industrial CNC applications with continuous high-torque loads, consult the torque rating of your specific belt and pulley combination.

Aluminum alloy naturally forms a thin oxide layer that provides moderate corrosion resistance in typical indoor workshop environments. For outdoor or high-humidity applications, consider applying a light coating of machine oil or using anodized variants if available. These pulleys are not recommended for direct immersion in water or corrosive chemical environments.

Measure your motor or drive shaft diameter with a caliper. Select the bore size that matches or is slightly larger than your shaft — the keyway and a set screw (if your application uses one) will secure the fit. Common motor shaft sizes: NEMA 17 stepper → 5mm (not covered by this range); NEMA 23 → 6.35mm or 8mm; servo motors → 8mm–14mm; larger servo/gearbox outputs → 14mm–25mm.

HTD-5M pulleys are suitable for 3D printer applications that use 5M belts, such as large-format CoreXY or Cartesian printers with higher torque requirements. Note that most desktop FDM printers (Ender, Prusa, Voron small format) use GT2 2mm pitch belts — verify your printer's belt pitch before ordering. If your printer uses HTD 5M belts, these pulleys are a direct fit.