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When a slipping or mismatched pulley throws off your axis calibration mid-print or derails a CNC pass, the cost is more than just wasted material — it's lost time and lost confidence in your machine. Engineers, makers, and automation integrators who demand repeatable motion control need a pulley they can trust. These S3M 3mm pitch timing belt pulleys are machined to keep your drive train locked in sync, run after run.
Each S3M timing belt pulley features a 3mm tooth pitch (S3M profile) with a tooth width of 11mm (approximately 0.43 in), compatible with standard 10mm wide S3M belts. Bore options range from 3mm to 25mm (approximately 0.12–0.98 in), and tooth counts span 15T to 120T, giving you precise gear-ratio flexibility. The body is typically machined from aluminum alloy with a natural or anodized finish; set-screw retention is standard on most bore sizes.
Typical use cases include CNC router X/Y axis drives, FDM 3D printer extruder and motion systems, light-duty conveyor and pick-and-place automation, and DIY robotics requiring low-backlash synchronous drive. Long-tail applications: S3M pulley for Ender 3 upgrade, S3M aluminum pulley for GRBL CNC, 3mm pitch synchronous pulley replacement.
| Belt Profile | S3M (3mm pitch, synchronous) |
|---|---|
| Tooth Pitch | 3mm (0.118 in) |
| Tooth Width | 11mm (0.43 in) |
| Compatible Belt Width | 10mm |
| Number of Teeth | See variant options (15T – 120T) |
| Bore Diameter | See variant options (3mm – 25mm) |
| Body Material | Aluminum alloy |
| Finish | Natural / anodized (varies by batch) |
| Bore Retention | Set-screw (radial) |
| Flange | Double-flanged |
| 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 20T driver paired with a 40T driven pulley gives a 2:1 reduction (half speed, double torque). For CNC and 3D printer motion axes, matching tooth counts on both ends gives a 1:1 ratio for direct speed mapping to your steps-per-mm setting.
Standard NEMA 17 stepper motors have a 5mm output shaft diameter. Select the 5mm bore variant. If your motor has a flat (D-cut) shaft, the set-screw will seat against the flat for a more secure grip. For NEMA 23 motors, the shaft is typically 6.35mm or 8mm — choose the 8mm bore in that case.
No. This pulley uses the S3M tooth profile (trapezoidal, 3mm pitch). GT2 belts use a curvilinear 2mm pitch profile, and HTD belts use a different curvilinear profile. Mixing profiles causes poor mesh, accelerated wear, and potential belt skipping. Always match the pulley profile to your belt profile exactly.
Aluminum alloy offers good natural oxidation resistance for indoor and light-industrial environments. For humid or mildly corrosive environments, anodized variants provide an additional oxide layer. These pulleys are not recommended for continuous immersion or highly corrosive chemical exposure without additional protective coating.
Maximum RPM and torque capacity depend on the specific tooth count, bore size, belt tension, and operating temperature. For typical CNC and 3D printer applications (low-to-medium load, under 3000 RPM), these pulleys perform reliably. For high-speed or high-torque industrial applications, contact us to confirm suitability for your specific duty cycle.
The standard bore is smooth (no keyway). The set-screw provides the primary retention. If your shaft has a keyway, the set-screw can still be used, but for high-torque applications a custom keyed bore is recommended. Contact us to confirm if a keyed bore option is available for your required size.
Slide the pulley onto the shaft to the desired axial position. Ensure the belt is routed before tightening. Tighten the set-screw(s) with the appropriate hex key to the manufacturer's recommended torque (typically 0.5–1.5 Nm for small bores). Use a straightedge or laser alignment tool to verify the pulley face is coplanar with the mating pulley to prevent belt tracking issues.
