GT2 2GT 80T-120T Timing Belt Pulleys 5mm-25mm Bore with Steps for CNC 3D Printer

Tooth count determines the pitch diameter and, combined with your motor pulley tooth count, sets the drive ratio. Larger tooth counts (e.g., 100T–120T) produce larger pitch diameters and are used on the driven side to reduce speed and increase torque. Match your belt length and center distance calculation to confirm the selected tooth count fits your frame geometry.

Common NEMA 17 stepper shafts are 5mm diameter; NEMA 23 shafts are typically 6.35mm (1/4 in) or 8mm. Measure your shaft diameter with calipers before ordering. For metric shafts, select the matching through-bore. For imperial shafts, the 6.35mm bore option is provided. If your shaft uses a key, select the corresponding keyway variant.

Through-hole variants use one or two set screws to clamp the pulley onto a smooth shaft. They are suitable for moderate torque and are easier to install and reposition. Keyway variants include a machined slot that accepts a standard parallel key, providing a positive mechanical lock between the shaft and pulley. Keyway variants are recommended for higher torque, reversing loads, or applications where set-screw creep is a concern.

Yes. These pulleys use the standard 2mm pitch GT2 curvilinear tooth profile and are compatible with GT2 and 2GT open or closed timing belts with a 6mm or 7mm width. Confirm your belt width matches the 7mm pulley face before ordering. Using a narrower belt on a wider pulley is acceptable; using a wider belt on a narrower pulley is not recommended.

The black anodized finish provides a hard oxide layer that resists mild corrosion, humidity, and abrasion better than bare aluminum. For heavily corrosive environments (salt spray, chemical exposure), additional protective measures such as periodic lubrication of the belt interface or sealed enclosures are advisable. The anodizing does not affect dimensional tolerances on the bore or tooth profile.

These pulleys are designed as driven (large) pulleys due to their high tooth counts (80T–120T). They are typically paired with a smaller motor pulley (e.g., 16T–20T) to achieve speed reduction. They can be used on any shaft that matches the bore diameter, whether motor-side or load-side, as long as the bore and keyway (if required) match the shaft specification.

Through-bore variants include M3 or M4 set screws (size varies by bore diameter). A standard hex key (Allen key) of the matching size is required for installation. Keyway variants do not rely on set screws for primary torque transmission; a key and retaining ring or shaft collar are used instead. Refer to your assembly drawing for the recommended fastener torque.