HTD 3M Timing Belt Pulley 12T-90T for 15mm Belt Reprap 3D Printer CNC Pitch 3mm

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 axis pulley gives a 2:1 reduction, halving speed and doubling torque. For most Reprap and CoreXY 3D printers, 20T is the standard motor pulley. For CNC routers requiring torque multiplication, larger tooth counts on the driven side (40T–90T) are common.

K-type pulleys have a standard round bore with one or two set-screw holes on the hub collar. They are the most common choice for stepper motor shafts (typically 4–8 mm) in 3D printers and light CNC machines. BF-type pulleys feature a flanged hub with a keyway-compatible bore, designed for applications where a key is used to transmit torque — such as servo motors, spindles, or any shaft where set-screw retention alone is insufficient under high torque or reversing loads.

The aluminum alloy body with anodized surface treatment provides good resistance to oxidation and mild corrosion in typical indoor and light-industrial environments. For prolonged outdoor exposure or contact with aggressive chemicals, additional protective measures (such as a clear coat or periodic lubrication of the bore interface) are advisable. The anodized layer also improves surface hardness, reducing wear at the bore-shaft interface.

Measure your motor or drive shaft diameter with a caliper. For NEMA 17 stepper motors, the standard shaft is 5 mm; for NEMA 23, it is typically 6.35 mm or 8 mm. For servo motors or spindles, shaft diameters of 10–25 mm are common. If your shaft has a keyway, select a BF-type pulley with the matching keyed bore designation (e.g., 8/3×1.4 mm means an 8 mm bore with a 3×1.4 mm keyway slot). If unsure, contact us to confirm before ordering.

Yes. The HTD 3M tooth profile is an industry-standard geometry defined by a 3 mm pitch and a specific rounded tooth form. These pulleys are dimensioned to mesh with any HTD 3M belt with a 15 mm width, regardless of brand. Avoid mixing HTD 3M pulleys with GT2 or trapezoidal MXL/XL belts — the tooth profiles are not interchangeable and will cause premature wear or skipping.

For 3D printers (Reprap, CoreXY, bed-slinger designs), 20T is the de facto standard for the motor pulley, balancing resolution and speed. For CNC routers where you need torque multiplication to drive a lead screw or rack, a smaller motor pulley (12T–16T) paired with a larger driven pulley (40T–90T) provides the necessary mechanical advantage. For laser cutters and light plotters, 20T–24T motor pulleys are typical.

Yes. NEMA 23 stepper motors commonly have 6.35 mm or 8 mm output shafts. Select a K-type pulley with the matching bore (6.35 mm or 8 mm) and your required tooth count. For higher-torque NEMA 23 applications, consider a BF-type pulley with a keyed bore to prevent shaft slippage under load. Confirm your motor shaft diameter before ordering.