S2M Timing Belt Pulleys 26-80Teeth Pitch 2mm AF-type With Keyway Width 11mm

The number of teeth determines the pulley's pitch diameter and, combined with your belt length and the mating pulley's tooth count, sets your drive ratio. For 3D printer axes, 20T–40T is typical; for higher-torque or lower-speed drives, 50T–80T gives more contact area and smoother load distribution. Use the formula: Pitch Diameter (mm) = (Teeth × Pitch) ÷ π to calculate the resulting diameter for your design.

Match the bore to your motor or drive shaft diameter exactly. The keyway size is paired to the bore: 8mm and 10mm bores use a 3×1.4mm keyway; 12mm and 10mm bores also offer a 4×1.8mm option; 12.7mm, 14mm, and 15mm bores use a 5×2.3mm keyway. Check your shaft's existing keyway slot dimensions before ordering to ensure a proper fit.

Yes. These pulleys conform to the S2M synchronous belt standard — 2mm tooth pitch, 11mm belt width. They are compatible with any S2M open-end or closed-loop timing belt of the same width. Do not use with S2M belts of different widths (e.g., 6mm or 15mm) as the flanges are sized for 11mm.

The aluminum alloy construction is well-suited for light-to-medium duty applications such as 3D printer axes, small CNC machines, laser cutters, and lab automation. For heavy industrial loads or high-shock environments, consider steel pulleys instead. The keyway connection significantly improves torque transmission compared to set-screw-only designs.

Aluminum alloy naturally forms a thin oxide layer that provides basic corrosion resistance in normal indoor environments. For humid or mildly corrosive environments, the anodized finish adds an additional protective layer. These pulleys are not recommended for submerged or highly corrosive chemical environments.

AF-type means the pulley has aluminum flanges on both sides of the tooth section. These flanges act as guides that keep the timing belt centered on the pulley and prevent it from walking off the edge during operation — especially important on long or lightly tensioned belt runs. Non-flanged pulleys rely on the mating pulley or idler to provide belt guidance.

The pulley is designed for keyway-and-key installation for maximum torque transmission. While you could theoretically use a set screw alone in very low-torque applications, the keyway slot is already machined and a matching key is recommended for reliable, slip-free operation. Keys are standard metric sizes and are widely available at hardware suppliers.

S2M (2mm pitch, trapezoidal tooth) is an older synchronous belt standard. GT2 (2mm pitch, curvilinear tooth) offers lower backlash and is now more common in 3D printers. Choose S2M if you are replacing an existing S2M belt drive or if your belt is specifically rated S2M. If starting a new build, verify which belt profile your belt supplier stocks for your width and length requirements.