HTD-5M 10-75Teeth Timing Belt Pulley Pitch 5mm With Keyway CNC Drive Width 16mm

The tooth count determines your drive ratio. Divide the driven pulley teeth by the driving pulley teeth to get the reduction ratio. For example, a 20T motor pulley paired with a 40T driven pulley gives a 2:1 reduction. For CNC routers and 3D printers, matching tooth counts on both ends (1:1) is common for direct-drive linear axes. Use a smaller tooth count on the motor side if you need torque multiplication.

Match the bore to your motor's output shaft diameter. Common NEMA 17 stepper motors use a 5mm shaft (not listed — check our other listings), NEMA 23 motors typically use 6.35mm or 8mm shafts, and NEMA 34 motors commonly use 12mm or 14mm shafts. Servo motors vary widely — check your motor datasheet. The bore must match the shaft exactly; a loose fit will cause vibration and positioning error even with a keyway installed.

K-type pulleys have no side flanges — the belt can slide laterally off the pulley if not constrained by the machine frame or belt guides. BF-type pulleys have machined flanges on both sides of the tooth section that physically retain the belt, preventing lateral walk-off. Choose BF-type for open-frame machines or long belt spans where lateral belt drift is a concern. K-type is suitable for enclosed belt paths or systems with external guides.

For unidirectional constant-load applications, a set screw alone may be sufficient. However, for reversing loads, high-acceleration servo drives, or any application where angular slip would cause positioning error, the keyway is strongly recommended. The keyway provides a positive mechanical lock that prevents rotational slip regardless of load direction. These pulleys include a machined keyway; you will need to supply a matching key stock cut to the appropriate length.

Yes, provided your belt has a 5mm HTD pitch and a width of 15mm or 16mm. The HTD-5M tooth profile is standardized, so these pulleys are compatible with any brand of HTD-5M synchronous belt. Verify the belt width matches the 16mm pulley face width — using a narrower belt is acceptable but reduces torque capacity; a wider belt will not seat correctly.

The pulleys are machined from aluminum alloy, which offers a good strength-to-weight ratio and low rotational inertia. Bare aluminum will oxidize slowly in humid or outdoor environments, forming a protective oxide layer. For prolonged exposure to moisture, salt spray, or corrosive atmospheres, consider applying a light coating of corrosion-inhibiting grease to the bore and keyway, or select a stainless steel alternative for your application.

The pitch diameter of an HTD-5M pulley equals (Number of Teeth × Pitch) ÷ π. For example, a 20T pulley: (20 × 5) ÷ 3.1416 ≈ 31.83mm pitch diameter. Belt length = 2 × Center Distance + π × (D1 + D2) ÷ 2 + (D2 − D1)² ÷ (4 × Center Distance), where D1 and D2 are the pitch diameters of the two pulleys. Round up to the nearest available standard belt length and adjust center distance accordingly.