GT2 Timing Belt Pulley Synchronous Wheel 20T-80T Teeth Width 7mm Bore 3mm-15mm

The tooth count determines your drive ratio. For a 1:1 ratio (same speed on both shafts), use identical pulleys on both ends. To reduce speed and increase torque, use a smaller pulley on the motor and a larger one on the driven shaft. Common 3D printer X/Y axes use 20T pulleys; larger CNC or robotic stages may use 30T–60T for smoother motion at higher belt speeds.

These pulleys have a 7mm tooth face width and are designed for standard 6mm-wide GT2 timing belts. Using a belt wider than 6mm may cause the belt to ride over the flanges; narrower belts will work but may track less reliably. Always match belt width to pulley specification.

A through-hole bore relies on one or two set screws to grip the shaft. This is adequate for most 3D printer and light CNC applications where torque is low and the shaft is smooth. A keyway bore adds a machined slot that mates with a key on the shaft, providing positive rotational locking — recommended for higher-torque drives, frequent direction reversals, or applications where set-screw loosening is a concern.

Yes. The GT2 2mm-pitch tooth profile is identical whether the belt is open-ended or a closed loop. Verify that the closed-loop belt's inner circumference matches the center distance and tooth count of your drive system. These pulleys mesh correctly with any standard GT2 belt regardless of loop type.

The pulleys are machined from aluminum alloy, which provides a good balance of low weight and adequate strength for typical desktop CNC, 3D printing, and light robotic applications. Aluminum pulleys are not recommended for heavy industrial drives with sustained high torque; for those applications, steel pulleys would be more appropriate. For the vast majority of DIY and maker use cases, aluminum GT2 pulleys are the standard choice.

Measure your motor or drive shaft diameter with a caliper. Common sizes: NEMA 17 steppers typically use a 5mm shaft; NEMA 23 steppers often use 6.35mm (1/4 in) or 8mm; servo motors vary widely. Select the bore that matches your shaft diameter exactly — a loose bore will cause runout and positioning errors even with set screws tightened. If your shaft has a flat (D-cut), a set screw bore is usually sufficient; if it has a keyway slot, select the matching keyway bore variant.

Yes. GT2 pulleys are commonly used in belt-reduction stages for Z-axis drives, where a small motor pulley drives a larger pulley attached to a lead screw or ball screw. Choose your tooth counts to achieve the desired reduction ratio (e.g., 20T motor / 40T driven = 2:1 reduction). For this application, a keyway bore on the driven pulley is recommended to prevent slip under the axial load of the Z-axis.