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When a slipping or mismatched pulley brings your CNC router, 3D printer, or conveyor line to a halt, you need a drop-in replacement that fits exactly right. These S3M timing belt pulleys are engineered for makers, machine builders, and automation engineers who demand repeatable, slip-free motion transmission without the guesswork of custom machining.
Each pulley is machined from aluminium alloy with an anodised finish, featuring an AF-type (set-screw) bore hub. The belt-contact width is 16 mm (0.63 in), with a 3 mm (0.118 in) tooth pitch conforming to the S3M synchronous belt standard. Tooth counts span from 15T to 60T, and bore diameters range from 4 mm to 25 mm (0.157 in – 0.984 in), covering the most common shaft sizes used in light-duty drive systems.
Typical applications include CNC router X/Y axis drives, desktop 3D printer extruder and motion systems, small robotic arm joints requiring precise angular positioning, and light-duty conveyor or indexing table synchronous drives.
| Belt Standard | S3M (Synchronous 3 mm Pitch) |
|---|---|
| Tooth Pitch | 3 mm (0.118 in) |
| Belt Width | 16 mm (0.63 in) |
| Tooth Count | 15T – 60T (see variant options) |
| Bore Diameter | 4 mm – 25 mm (see variant options) |
| Hub Type | AF-type (set-screw) |
| Material | Aluminium alloy |
| Finish | Anodised |
| Quantity per Order | 1 piece |
| Weight | See variant options |
The tooth count determines your drive ratio. Divide the driven pulley tooth count by the driving pulley tooth count to get the speed reduction ratio. For example, a 15T driver paired with a 30T driven pulley gives a 2:1 speed reduction (and 2× torque increase). Match your required output speed and torque to select the correct pairing.
Measure your motor or drive shaft diameter with a calliper. Select the bore that matches exactly — for example, a 6.35 mm bore fits a standard ¼-inch (0.25 in) shaft. If your shaft is metric, choose the matching metric bore. The AF-type set screw secures the pulley once installed; no additional machining is needed for most applications.
Use any standard S3M synchronous timing belt with a 3 mm pitch and a width of 16 mm or narrower. The belt width should not exceed the pulley's 16 mm belt contact width. S3M belts are widely available in closed-loop and open-ended forms for CNC, 3D printing, and automation applications.
Yes, for light-to-medium duty CNC applications. The aluminium alloy construction provides adequate rigidity for typical desktop and benchtop CNC routers. For heavy-duty industrial CNC machines with high cutting forces, verify that the S3M belt system's torque rating meets your load requirements before ordering.
The anodised aluminium finish provides good resistance to oxidation and light moisture exposure typical of indoor workshop environments. These pulleys are not rated for continuous immersion or highly corrosive chemical environments. For outdoor or wet applications, consider additional protective measures.
Yes. S3M pulleys are commonly used in 3D printer extruder drives and motion systems. Verify that your printer's belt is S3M pitch (3 mm) and that the bore matches your stepper motor shaft diameter — typically 5 mm for NEMA 17 motors. Select the tooth count that matches your printer's original pulley specification to maintain correct steps-per-mm calibration.
AF-type (also called plain bore with set screw) means the bore is smooth (no keyway) and a set screw on the hub clamps the pulley to the shaft. This is the most common type for light-duty drives and is easy to install and adjust. Keyway-type hubs are used for higher-torque applications where a key prevents rotational slipping under heavy load.
