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Engineers and makers who rely on synchronous drive systems know the frustration of pulleys that slip, wobble, or fail to mesh cleanly with S3M belts. Whether you are building a CNC router, a 3D printer, or an automated conveyor, mismatched or poorly machined pulleys introduce backlash and ruin repeatability. These S3M timing belt pulleys are designed for those who need dimensional accuracy and reliable engagement every time.
Each pulley is machined from aluminum alloy and features a step (flanged) drive profile with a tooth width of 16mm (0.63 in) and a belt pitch of 3mm (0.118 in). Tooth counts range from 42T to 150T, and bore diameters span 5mm to 25mm (0.197 in to 0.984 in), covering the most common shaft sizes used in motion-control applications.
Typical use cases include S3M belt drive systems for desktop CNC machines requiring low-backlash transmission, 3D printer extruder and axis drives where consistent tooth engagement prevents layer shifting, and light-duty robotics or automation rigs where a compact step pulley profile saves axial space while maintaining torque transfer.
| Belt Standard | S3M (Synchronous 3mm pitch) |
|---|---|
| Pitch | 3mm (0.118 in) |
| Tooth Width | 16mm (0.63 in) |
| Drive Style | Step Drive (Flanged) |
| Number of Teeth | 42T / 44T / 45T / 46T / 48T / 50T / 52T / 54T / 56T / 58T / 60T / 65T / 70T / 72T / 75T / 80T / 90T / 100T / 120T / 140T / 150T |
| Bore Diameter | 5 / 6 / 6.35 / 8 / 10 / 12 / 12.7 / 14 / 15 / 16 / 17 / 18 / 19 / 20 / 22 / 24 / 25mm |
| Material | Aluminum alloy |
| Finish | See variant options |
| Weight | See variant options |
| Quantity per Order | 1 piece |
The tooth count determines your drive ratio. Divide the driven pulley teeth by the driving pulley teeth to get the ratio. For example, a 60T driven pulley paired with a 20T motor pulley gives a 3:1 reduction. Choose a tooth count that achieves your target speed or torque ratio while keeping the belt span within your frame constraints.
Match the bore to your shaft diameter exactly. Common metric sizes are 5, 6, 8, 10, 12, 14, 15, 16, 17, 18, 19, 20, 22, 24, and 25mm. For imperial shafts, select 6.35mm (1/4") or 12.7mm (1/2"). If your shaft requires a keyway or set-screw, verify the hub wall thickness is sufficient for your bore size before ordering.
Yes. These pulleys are machined to the S3M tooth profile standard (3mm pitch). They are compatible with any S3M open-end or closed-loop timing belt with a tooth width of 16mm or narrower. Do not use with GT2, HTD, or other pitch standards — the tooth geometry is not interchangeable.
The aluminum alloy construction provides a good strength-to-weight ratio for light to medium duty applications such as 3D printers, CNC routers, and small automation systems. For heavy industrial loads or high-speed continuous operation, verify the torque rating of your belt and pulley combination against your application requirements. The step (flanged) design helps prevent belt walk, which reduces side-load stress on the pulley hub.
Aluminum alloy naturally forms a thin oxide layer that provides moderate corrosion resistance in typical indoor workshop and laboratory conditions. For prolonged exposure to moisture, salt spray, or harsh chemicals, consider applying an additional protective coating or selecting a stainless steel alternative. These pulleys are not rated for submersion or continuous outdoor exposure.
A step drive (flanged) pulley has raised shoulders on one or both sides of the tooth section. These flanges act as guides that keep the timing belt centered on the pulley face, preventing lateral drift during operation. A flat (unflanged) pulley relies on the belt tension and system alignment alone to stay on track. For most DIY and light-industrial builds, a flanged pulley is the safer choice as it tolerates minor misalignment without belt derailment.
Yes. S3M pulleys are widely used in desktop CNC routers, laser cutters, and 3D printers where the 3mm pitch provides a good balance of resolution and load capacity. Confirm that your existing belt is S3M standard and that the bore matches your stepper motor shaft before purchasing. The 16mm tooth width is compatible with most standard S3M belt widths used in these machines.
