GT2 Timing Belt Pulley 20-80 Teeth 6mm Teeth Width Bore 3mm-15mm For 3D

The tooth count determines your drive ratio. Most Cartesian 3D printers (Ender 3, CR-10, etc.) use 20-tooth pulleys on the motor shaft paired with an idler. CoreXY machines often use 20 T as well. If you are building a custom geardown stage or a slower, higher-torque axis, a larger tooth count (e.g., 40 T or 60 T) on the drive side reduces speed and increases torque. Match the tooth count to your belt loop length and axis geometry.

Standard NEMA 17 stepper motors have a 5 mm output shaft. Select the variant with Bore 5 mm. If your motor has a D-cut shaft, the set screw will engage the flat to prevent rotation. For NEMA 23 motors, the shaft is typically 6.35 mm (1/4 inch) — choose the 6.35 mm bore variant.

Yes. GT2 is an open industry standard defined by a 2 mm tooth pitch and a specific curvilinear tooth profile. Any GT2-profile belt with 6 mm width — regardless of brand — will mesh correctly with these pulleys. Confirm your belt is labeled GT2 (not T2.5, HTD 3M, or MXL) before ordering.

The set screw provides firm clamping on smooth shafts and positive locking on D-cut or flat-keyed shafts. For typical 3D printer and light CNC loads (belt tensions under ~30 N), set-screw retention is sufficient. For heavy-duty applications with high belt tension or shock loads, consider using a shaft with a flat or keyway to maximize grip. Always torque the set screw fully before operation.

For GT2 belt applications — where the belt is typically rubber or polyurethane with fiberglass or steel cord reinforcement — aluminum pulleys offer an excellent service life. The belt material is softer than the pulley, so wear occurs on the belt rather than the pulley teeth. Aluminum pulleys are the industry standard for desktop 3D printers and light CNC machines precisely because they balance durability with low rotational inertia.

These are drive pulleys designed to be fixed to a rotating shaft via set screw. They are not pre-fitted with bearings. To use a pulley as a freewheeling idler, you would need to press-fit or slip-fit an appropriate bearing (e.g., 625ZZ or 624ZZ) into the bore and mount it on a static bolt. Alternatively, dedicated idler pulleys with integrated bearings are a simpler solution for idler positions.

For a GT2 pulley, the pitch diameter (PD) = (Number of Teeth × Pitch) ÷ π = (T × 2) ÷ π. For example, a 20-tooth pulley has PD ≈ 12.73 mm. The outer diameter is slightly smaller than the pitch diameter due to the GT2 tooth geometry. Use the pitch diameter for belt-length calculations. If you need the exact outer diameter for a specific variant, please contact us to confirm before ordering.