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When a slipping or misaligned drive pulley brings your CNC router, 3D printer, or automation project to a halt, you need a replacement that fits exactly right the first time. This S2M timing pulley (Zahnriemenrad / Riemenscheibe) is engineered for engineers, makers, and machine builders who cannot afford dimensional guesswork in their synchronous drive systems.
Each pulley is machined from aluminum alloy and features the S2M tooth profile (2 mm pitch, rounded tooth form). Available in two belt widths — 6 mm and 10 mm — with tooth counts ranging from 20 Z to 80 Z. Bore diameters span 4 mm to 15 mm (approximately 0.16 in to 0.59 in), with select variants offering a keyway bore (K3 / K4 / K5) for positive shaft engagement. Overall pulley outer diameter scales with tooth count, typically 12–52 mm (approx. 0.47–2.05 in).
Typical use cases include open-loop and closed-loop CNC axis drives requiring low-backlash S2M belt pairing, extruder and Z-axis assemblies in desktop 3D printers using 2 mm pitch belts, and lightweight robotic arm joints or conveyor indexing systems where a compact synchronous pulley with a precise bore fit is critical.
| Belt Profile | S2M (2 mm pitch, synchronous) |
|---|---|
| Tooth Count | 20 Z / 22 Z / 24 Z / 25 Z / 26 Z / 28 Z / 30 Z / 32 Z / 34 Z / 35 Z / 48 Z / 50 Z / 55 Z / 60 Z / 70 Z / 80 Z |
| Belt Width | 6 mm or 10 mm (select variant) |
| Bore Diameter | 4 / 5 / 6 / 6.35 / 8 / 10 / 12 / 12.7 / 14 / 15 mm; keyway variants: 8K3, 10K3, 10K4, 12K4, 12.7K5, 14K5, 15K5 |
| Material | Aluminum alloy |
| Outer Diameter | See variant options (scales with tooth count) |
| Hub / Flange | See variant options |
| Surface Finish | Natural aluminum (uncoated) |
| Quantity per Order | 1 piece |
The tooth count determines the pulley's pitch diameter and, combined with your motor pulley, sets the drive ratio. For a 1:1 ratio use identical tooth counts on both pulleys. For speed reduction, use a larger tooth count on the driven pulley. Common CNC and 3D printer setups use 20 Z driver pulleys paired with 20–40 Z driven pulleys. Refer to your machine's belt routing diagram for the correct count.
A plain bore relies on a set screw to grip the shaft, which can slip under high torque or vibration. A keyway bore (K3, K4, K5 — where the number indicates the keyway width in mm) uses a matching key inserted between the shaft and pulley hub, providing a positive mechanical lock. Choose a keyway variant when your shaft has a pre-cut keyway or when you need reliable torque transmission without slippage.
Yes — these pulleys are machined to the standard S2M tooth profile (2 mm pitch, rounded tooth form) and are compatible with any S2M synchronous belt of the matching width (6 mm or 10 mm). They are not compatible with GT2, HTD, or other belt profiles, even if the pitch appears similar. Always confirm both pitch and width before ordering.
Use a digital caliper to measure the shaft diameter at the point where the pulley will sit. Round to the nearest standard bore size listed in the variant options (4, 5, 6, 6.35, 8, 10, 12, 12.7, 14, or 15 mm). A bore that is too large will cause runout; a bore that is too small will not fit. For shafts with an existing keyway, select the matching keyway bore variant (e.g., 8K3 for an 8 mm shaft with a 3 mm keyway).
The aluminum alloy construction keeps weight low and handles the speeds typical of CNC routers, 3D printers, and light robotics (generally up to several thousand RPM depending on belt tension and alignment). For very high torque applications, the keyway bore variants provide significantly better shaft grip than plain bore with set screw. Ensure proper belt tension and pulley alignment to maximize service life.
It is not recommended. A 6 mm belt on a 10 mm pulley will track off-center and may derail under load. A 10 mm belt on a 6 mm pulley will overhang the flanges and risk damage. Always match the belt width to the pulley width exactly. Select the 6 mm variant for 6 mm S2M belts and the 10 mm variant for 10 mm S2M belts.
Aluminum alloy offers natural oxidation resistance suitable for indoor workshop, laboratory, and light industrial environments. The natural (uncoated) finish is not rated for prolonged exposure to salt spray, acids, or high-humidity outdoor conditions. If your application involves moisture or corrosive atmospheres, consider applying a light machine oil or anodizing the pulley after purchase.
