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When belt slip, backlash, or mismatched bore sizes derail your motion system, the root cause is almost always a pulley that wasn't engineered to spec. Makers, engineers, and automation builders who demand repeatable positioning need a GT2 timing pulley they can trust across every axis and every revision.
These AF-type GT2 timing pulleys are machined from aluminum alloy with an anodized finish. Available in 40T, 45T, and 48T tooth counts, with bore diameters ranging from 4 mm to 15 mm (approximately 0.157 in to 0.591 in). Tooth width is 11 mm, matching standard 2GT open-loop and closed-loop belts. Optional keyway widths of 3 mm, 4 mm, or 5 mm are available on select bore sizes for positive shaft locking.
Typical use cases include 3D printer X/Y axis drives (GT2 belt, 2GT profile), CNC router and laser cutter feed systems requiring low-backlash synchronous drive, and robotics joint actuators where shaft-to-pulley concentricity is critical for repeatable positioning.
| Belt Profile | GT2 / 2GT |
|---|---|
| Tooth Count | 40T / 45T / 48T (see variant options) |
| Tooth Width | 11 mm |
| Bore Diameter | 4, 5, 6, 6.35, 8, 10, 12, 12.7, 14, 15 mm (see variant options) |
| Keyway Width | Without keyway / 3 mm / 4 mm / 5 mm (see variant options) |
| Material | Aluminum alloy |
| Surface Finish | Anodized |
| Pulley Type | AF-type (flanged) |
| Pitch | 2 mm (GT2) |
| Compatible Belt Width | 6 mm / 9 mm (typical for 2GT) |
| Quantity per Pack | 1 / 2 / 3 pcs (see variant options) |
| Weight | See variant options |
The tooth count determines your drive ratio and linear speed per motor revolution. A 40T pulley moves less belt per revolution than a 48T, giving finer resolution at the same motor RPM. For most 3D printer CoreXY or Cartesian builds, 20T on the motor and 40T on the idler/driven axis is standard. If you need a 1:1 ratio or a specific gear reduction, match both pulleys to your design. When in doubt, 40T is the most common choice for direct-drive 2GT belt systems.
Measure your motor or drive shaft diameter with calipers before ordering. Common NEMA 17 stepper shafts are 5 mm; NEMA 23 shafts are typically 6.35 mm (1/4 in) or 8 mm. Servo and DC motor shafts vary widely. Choose the bore that matches your shaft exactly — a loose fit causes runout and belt skip. If your shaft is imperial (e.g., 1/4 in = 6.35 mm), select the 6.35 mm bore option.
A keyway provides a mechanical lock between the shaft and pulley, preventing rotational slip under high torque or reversing loads — common in CNC routers and robotics. If your shaft has a keyway slot machined into it, match the keyway width (3 mm, 4 mm, or 5 mm) to that slot. If your shaft is smooth or you plan to use a set screw only, select "without keyway." Note that not all bore sizes offer every keyway width; check the variant options for your chosen bore.
Yes. These pulleys use the GT2 (2GT) tooth profile with a 2 mm pitch, which is the industry-standard profile for open-loop and closed-loop 2GT timing belts. They are compatible with 6 mm and 9 mm wide 2GT belts. Verify that your belt width does not exceed the 11 mm tooth width of the pulley to ensure full tooth engagement.
The aluminum alloy body provides a good strength-to-weight ratio suitable for the torque loads typical in 3D printing, light CNC, and robotics applications. The anodized surface adds hardness and corrosion resistance. For very high-torque industrial applications with continuous heavy loads, verify that the pulley bore and keyway dimensions are adequate for your specific torque requirements before use.
Yes. Each variant includes a quantity option of 1, 2, or 3 pieces. Select the quantity that matches your build — for example, a CoreXY printer typically requires two identical pulleys on the driven axis. Ordering a multi-piece pack is more economical than placing separate single-unit orders.
AF-type pulleys feature integrated flanges on both sides of the tooth section. These flanges keep the belt centered on the pulley and prevent lateral belt walk-off during operation — particularly important on long belt runs or high-speed axes. Standard (non-flanged) pulleys rely on belt tension and guide geometry alone. For most 3D printer and CNC applications, AF-type flanged pulleys are the recommended choice for reliable belt tracking.
