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When a skipped tooth or a loose bore fit derails your print mid-job or throws off your CNC axis, the root cause is almost always a poorly machined pulley. Engineers, makers, and automation builders who demand repeatable motion need a GT2 timing belt pulley they can trust across thousands of cycles — and that starts with tight dimensional tolerances and a secure shaft interface.
This GT2 timing belt pulley series covers 14 to 30 teeth, available in 6 mm and 10 mm belt widths (teeth width). Bore diameters range from 3 mm to 15 mm, including standard round bores and K-type keyway bores (e.g., 8K3, 10K3, 10K4, 12K4) for positive torque transmission without set-screw slip. The pulley body is machined from aluminum alloy, with a natural or anodized finish depending on variant. Outer diameter scales with tooth count, typically 11–20 mm (~0.43–0.79 in); hub length is typically 14–22 mm (~0.55–0.87 in).
Typical use cases include FDM 3D printer X/Y axis drives (GT2 belt-driven Cartesian and CoreXY systems), desktop CNC router feed axes, and lightweight robotic joint actuators where low backlash and consistent pitch are critical for positional accuracy.
Wide tooth count selection lets you dial in the exact drive ratio for your motion system — from compact 14T idler-adjacent configurations to larger 30T pulleys for higher torque applications.
Choose the belt width that matches your existing GT2 belt. The 10 mm width carries higher lateral load and suits wider-format printers and CNC machines.
K-type keyway variants (8K3, 10K3, 10K4, 12K4) provide positive mechanical engagement with keyed shafts, eliminating rotational slip under load — essential for high-torque or high-speed axes.
Standard round bores from 3 mm to 15 mm cover the most common stepper motor and servo shaft sizes, including 3.175 mm (1/8 in) and 6.35 mm (1/4 in) imperial shafts.
Machined aluminum body keeps rotating mass low — reducing motor load and improving dynamic response — while maintaining the rigidity needed for accurate tooth engagement over extended use.
Tooth profile conforms to the GT2 standard (2 mm pitch, curvilinear tooth form), ensuring smooth, low-noise meshing and minimal backlash with compatible GT2 belts.
| Belt Profile | GT2 (2 mm pitch) |
|---|---|
| Number of Teeth | 14 / 15 / 16 / 18 / 20 / 22 / 24 / 25 / 26 / 28 / 30 |
| Belt Width (Teeth Width) | 6 mm / 10 mm |
| Bore Diameter | 3, 3.175, 4, 5, 6, 6.35, 8, 10, 12, 12.7, 14, 15 mm; K-type: 8K3, 10K3, 10K4, 12K4 |
| Bore Type | Round bore (standard) / K-type keyway bore |
| Material | Aluminum alloy |
| Outer Diameter (approx.) | See variant options (scales with tooth count; typically 11–20 mm) |
| Hub Length (approx.) | See variant options (typically 14–22 mm) |
| Flange | Flanged (retains belt laterally) |
| Finish | See variant options |
| Compatible Belt | GT2-6 (6 mm width) / GT2-10 (10 mm width) |
| Quantity per Order | 1 piece |
The tooth count determines your drive ratio and the pulley's outer diameter. For most desktop 3D printers (Cartesian or CoreXY), 20T is the standard choice on the motor shaft. Smaller tooth counts (14–16T) give a more compact package but increase belt wrap angle sensitivity; larger counts (24–30T) suit applications needing higher torque multiplication or a larger pitch diameter. Match the tooth count to your belt length and center distance calculation.
A standard round bore is secured to the shaft using one or two set screws. A K-type keyway bore has a machined slot that accepts a matching key on the shaft, creating a positive mechanical lock that prevents rotational slip under high torque or shock loads. K-type variants (e.g., 10K3 = 10 mm bore with 3 mm keyway width) are recommended for CNC spindle drives, servo axes, or any application where set-screw retention alone is insufficient.
Most NEMA 17 stepper motors used in 3D printers have a 5 mm diameter shaft. Select the variant with a 5 mm bore diameter and 6 mm belt width for a direct fit. If your motor has a flat (D-cut) shaft, a set screw tightened against the flat provides adequate retention without a keyway. Measure your shaft diameter before ordering if you are unsure.
Yes. The GT2 tooth profile (2 mm pitch, curvilinear form) is an open industry standard. These pulleys are dimensionally compatible with GT2 timing belts from any manufacturer that conforms to the GT2 specification. Ensure you match the belt width: use GT2-6 belts with 6 mm-width pulleys and GT2-10 belts with 10 mm-width pulleys.
Aluminum alloy offers a good strength-to-weight ratio for the load levels typical in 3D printing, light CNC, and robotics. The GT2 belt itself is generally the wear component in the drive system, not the pulley. For heavy industrial duty cycles with steel belts or very high belt tension, a steel pulley would be more appropriate. For the intended applications (3D printers, desktop CNC, robotics), aluminum pulleys provide long service life under normal operating conditions.
Not directly. The 10 mm variant has a wider tooth section and requires a 10 mm wide GT2 belt. If your machine uses 6 mm belts, select the 6 mm belt-width variant. Upgrading from 6 mm to 10 mm belts can increase belt load capacity and reduce stretch, but requires replacing both the pulley and the belt, and verifying that your frame and idlers accommodate the wider belt.
Two common imperial shaft sizes have direct metric equivalents in this range: 1/8 inch = 3.175 mm (select the 3.175 mm bore variant) and 1/4 inch = 6.35 mm (select the 6.35 mm bore variant). For other imperial sizes, convert to mm (multiply inches × 25.4) and select the closest available bore. If the bore is slightly larger than your shaft, a set screw against a D-flat or a thin shim can compensate.
