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When a slipping or mismatched pulley causes positioning errors in your motion system, every project suffers. Engineers, CNC builders, and robotics hobbyists who demand repeatable, slip-free power transmission need a synchronous wheel they can trust across a wide range of shaft sizes and tooth counts. These S3M timing belt pulleys are designed exactly for that audience.
Each S3M timing belt pulley features an AF-type (set-screw) hub machined from aluminum alloy, with a 3mm pitch tooth profile and an 11mm belt-contact width. The tooth count range spans 65T to 120T, and bore options run from 5mm to 25mm (approximately 0.20 in to 0.98 in), covering the most common motor and shaft diameters used in light-duty and medium-duty drive systems.
Typical applications include CNC router X/Y axis drives requiring an S3M 80T synchronous wheel with 10mm bore, 3D printer extruder and Z-axis assemblies using a compact S3M 65T pulley, and small robotic arm joints where an S3M 100T timing pulley with 8mm bore provides the needed gear reduction. The AF-type hub allows quick shaft changes without full disassembly, making these pulleys a practical choice for iterative prototyping and production runs alike.
Available from 65T to 120T (S3M65T through S3M120T), giving you precise gear-ratio flexibility for CNC, robotics, and automation builds without sourcing from multiple suppliers.
The AF-type hub design uses a radial set screw to lock onto the shaft, enabling fast installation and removal. No press-fit tooling required — ideal for prototyping and field maintenance.
Engineered to the S3M standard: 3mm tooth pitch and 11mm belt-contact width ensure accurate meshing with S3M synchronous belts, minimizing backlash and maintaining positional accuracy.
Choose from 5, 6, 8, 10, 12, 14, 15, 17, 19, 20, or 25mm bores to match stepper motors, servo shafts, and lead screws commonly found in DIY and industrial motion systems.
Machined from aluminum alloy for a balance of low rotational inertia and sufficient strength for light-to-medium duty drives. The material resists corrosion in typical indoor workshop and lab environments.
The toothed profile locks mechanically with the belt, eliminating the slip inherent in V-belt or flat-belt systems. This makes these pulleys suitable for stepper-motor-driven axes where lost steps cannot be tolerated.
| Belt Standard | S3M (Super Torque 3mm pitch) |
|---|---|
| Tooth Pitch | 3mm |
| Belt Width | 11mm |
| Tooth Count Options | 65T, 68T, 70T, 72T, 75T, 76T, 80T, 90T, 100T, 110T, 120T |
| Bore Options | 5 / 6 / 8 / 10 / 12 / 14 / 15 / 17 / 19 / 20 / 25mm |
| Hub Type | AF-type (set-screw) |
| Material | Aluminum alloy |
| Outer Diameter | See variant options |
| Flange | See variant options |
| Finish | Natural / anodized (see variant options) |
| Quantity per Order | 1 piece |
The tooth count determines the pulley's pitch diameter and, combined with the tooth count of the mating pulley, sets your drive ratio. A higher tooth count means a larger diameter pulley. For example, pairing an S3M 80T drive pulley with an S3M 20T driven pulley gives a 4:1 reduction. Calculate your required ratio first, then select tooth counts that achieve it while fitting within your frame clearance.
Match the bore to your motor's output shaft diameter. Common NEMA 17 stepper motors use a 5mm shaft, NEMA 23 motors typically use an 8mm shaft, and larger servo motors may use 10–20mm shafts. Measure your shaft with calipers before ordering. The AF-type set screw accommodates minor shaft tolerance variation but cannot compensate for a bore that is too large.
These pulleys conform to the S3M open standard (3mm pitch, trapezoidal tooth profile). They are compatible with any S3M synchronous belt of 11mm width from any manufacturer that follows the standard. Always verify the belt width matches the 11mm pulley face before assembly.
The AF-type set screw provides adequate holding force for light-to-medium duty applications such as CNC routers, 3D printers, and small robotic joints. For high-torque or shock-load applications, consider adding a keyway or using a shaft with a flat for the set screw to bear against. Always torque the set screw to the fastener manufacturer's specification and re-check after initial run-in.
Aluminum alloy naturally forms a thin oxide layer that protects against corrosion in typical indoor environments with normal humidity. These pulleys are not recommended for continuous exposure to water, salt spray, or aggressive chemicals. For outdoor or wet environments, consider applying a light protective coating or selecting a stainless-steel alternative.
Yes. S3M pulleys can be used on both the motor (drive) side and the load (driven) side. Simply select the appropriate tooth count for each position to achieve your desired speed or torque ratio. Ensure both pulleys share the same 3mm pitch and 11mm belt width for proper meshing.
S3M uses a trapezoidal tooth profile with a 3mm pitch, which is an older but widely used standard. GT2 (Gates Tooth) uses a curvilinear profile for lower backlash and is common in 3D printers. HTD uses a rounded tooth for higher torque capacity. These profiles are not interchangeable — always match the pulley standard to your belt standard.
