2GT Timing Pulley Synchronous Wheel 60-78 Teeth 10mm Belt 5mm-20mm Bore for 3D

The tooth count determines your pulley's pitch diameter and, combined with your motor pulley tooth count, sets the belt drive ratio. For 3D printer CoreXY or Cartesian axes, 20-tooth motor pulleys paired with these 60–78 tooth idler or driven pulleys create reduction ratios from 3:1 to ~3.9:1. For direct-drive or 1:1 belt runs, match the tooth count on both ends. Use the formula: ratio = driven teeth ÷ drive teeth.

Most NEMA 17 stepper motors use a 5mm shaft; NEMA 23 motors typically use an 8mm or 1/4" (6.35mm) shaft. Measure your shaft diameter with calipers before ordering. If your shaft has a flat or keyway, select the matching keyway variant (e.g., Bore 8 Keyway 3mm) for positive torque transfer without relying solely on the set screw.

Yes. The 2GT tooth profile is an industry-standard 2mm-pitch curvilinear form, dimensionally identical to GT2. These pulleys are compatible with any 10mm-wide GT2 or 2GT open or closed-loop belt regardless of brand, as long as the belt pitch is 2mm and the width is 10mm.

Aluminum alloy pulleys are standard in 3D printing and light CNC applications where belt tensions typically range from 5N to 30N. The hard-anodized surface resists groove wear from belt contact. For heavy-duty industrial drives with sustained high tension, consider steel pulleys instead. For typical maker and workshop use cases, aluminum is the appropriate choice.

Hard anodizing creates an aluminum oxide layer that is significantly harder than bare aluminum and provides good resistance to oxidation, mild chemical exposure, and abrasion. In normal indoor workshop conditions — including exposure to cutting fluid mist or humidity — the finish performs reliably. Avoid prolonged immersion in strong acids or alkalis.

These pulleys are designed as driven or drive pulleys with a set screw for shaft mounting. To use one as a smooth idler, you would need to press-fit a bearing into the bore — the bore diameter must match your bearing's outer diameter. For dedicated idler use, a flanged bearing or purpose-built idler pulley is typically a more direct solution.

A plain bore relies entirely on the set screw to prevent the pulley from rotating on the shaft. A keyway bore adds a rectangular slot that mates with a matching key on the shaft, providing a positive mechanical lock that transfers torque without depending on set screw friction alone. Keyway variants are recommended for higher-torque applications or where the set screw may loosen under vibration.