2GT Timing Belt Pulley 16T-40T Bore 3-13mm For 6mm Wide Timing Belt, CNC Motor

The tooth count determines your drive ratio and pitch diameter. Smaller tooth counts (16T, 20T) are common on drive pulleys paired with larger idler pulleys for mechanical advantage. 20T is the most widely used size for CoreXY and Cartesian 3D printers. Larger counts (30T–40T) suit applications where you want a larger pitch diameter to increase linear speed per motor revolution or reduce belt wrap angle on long spans.

Measure your motor shaft diameter with calipers before ordering. NEMA 17 steppers typically use a 5 mm shaft; NEMA 23 steppers commonly use an 8 mm shaft. Hobby DC motors and small servo motors often use 3.17 mm (1/8 in) or 6.35 mm (1/4 in) shafts. Select the bore that matches your shaft — the set screw will secure it in place. Do not select a bore larger than your shaft diameter.

Yes. The 2GT tooth profile is mechanically identical to the GT2 profile — both use a 2 mm pitch curvilinear tooth geometry. These pulleys will mesh correctly with any standard GT2 or 2GT open or closed-loop timing belt that is 6 mm wide. Confirm your belt width is 6 mm before ordering.

The set screw provides adequate retention for typical CNC and 3D printer torque loads when properly tightened against a flat on the motor shaft (if present) or directly against a round shaft. For high-torque or high-vibration environments, ensure the set screw is tightened with the correct hex key and consider applying a small amount of thread-locking compound. Flat-sided shafts provide significantly better anti-rotation resistance than round shafts.

The anodized aluminum finish provides a hard, wear-resistant surface layer that resists oxidation under normal indoor workshop and laboratory conditions. Aluminum pulleys are well-suited for dry or lightly lubricated belt drive environments. Avoid prolonged exposure to strong acids, alkalis, or salt-spray environments, which can degrade the anodize layer over time.

These pulleys are designed as drive pulleys with a set-screw hub for shaft mounting. They can be used as idler pulleys by mounting them on a bolt or shaft of the appropriate bore diameter with a bearing inserted, but they do not include integrated bearings. If you need a flanged idler with a built-in bearing, look for a dedicated idler pulley product. For simple tensioner or redirecting idler use on a bolt, these work well with an appropriately sized bearing pressed into the bore.

A standard CoreXY printer typically requires 2 drive pulleys (one per motor). A Cartesian printer usually needs 1 drive pulley per axis. Order a 2-pack for a single CoreXY build, or a 5-pack if you are building multiple machines or want spares on hand. The 10- and 20-pack options offer the best per-unit value for workshop stock or small-batch production.