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When a slipping or mismatched pulley throws off your CNC router, 3D printer, or conveyor drive, the entire project stalls. Engineers, makers, and machine builders who need repeatable, slip-free motion rely on S3M timing belt pulleys to keep every axis locked in sync. This listing covers the full S3M 65T–120T range, letting you match the exact tooth count and bore your application demands without compromise.
Each S3M timing belt pulley in this range features a 3mm pitch (tooth-to-tooth spacing), a 16mm belt-contact width, and an AF-type hub with a set-screw bore. Tooth counts span from 65T to 120T, giving pitch diameters from approximately 62mm to 115mm (roughly 2.44" to 4.53"). Bore options run from 8mm to 25mm (0.31" to 0.98") to suit common motor and shaft sizes. The body is machined from aluminum alloy with an anodized or natural finish depending on variant.
Typical use cases include CNC router X/Y axis drives where tooth count determines travel-per-revolution, 3D printer Z-axis or extruder geartrains requiring low backlash S3M belt pulley pairing, and light industrial conveyor or pick-and-place automation where a synchronous drive pulley with a 3mm pitch belt ensures positional accuracy across long duty cycles.
| Belt Standard | S3M (3mm pitch, rounded tooth profile) |
|---|---|
| Tooth Pitch | 3mm |
| Number of Teeth | 65T / 70T / 72T / 75T / 76T / 80T / 90T / 100T / 110T / 120T |
| Pitch Diameter Range | Approx. 62mm–115mm (2.44"–4.53") — varies by tooth count |
| Belt Width (Pulley) | 16mm |
| Compatible Belt Width | 15mm or 16mm S3M timing belt |
| Hub Type | AF-type (set-screw clamping, no keyway) |
| Bore Diameter Options | 8 / 10 / 12 / 14 / 15 / 17 / 19 / 20 / 25mm |
| Material | Aluminum alloy |
| Finish | See variant options |
| Flanges | See variant options |
| Weight (per piece) | See variant options |
| Quantity per Order | 1 piece |
The tooth count determines the pitch diameter and, combined with your belt length and the driven pulley's tooth count, sets your drive ratio. For CNC axes, divide your desired travel-per-step by the motor's step angle and belt pitch to calculate the required tooth count. If you're replacing an existing pulley, count the teeth on the original or measure the pitch diameter (PD = Teeth × Pitch ÷ π).
NEMA 17 stepper motors typically have a 5mm output shaft — however, this listing starts at 8mm bore. You may need a 5mm-to-8mm shaft adapter or a different pulley series for NEMA 17. NEMA 23 motors commonly use 6.35mm (1/4") or 8mm shafts, so the 8mm bore variant is a direct fit for 8mm NEMA 23 shafts. Always verify your motor's shaft diameter in its datasheet before ordering.
AF-type hubs use a radial set screw to clamp the pulley onto the shaft. They are well-suited for light-to-medium duty CNC, 3D printing, and automation applications. For high-torque or reversing-load applications, consider adding a flat on the shaft to prevent rotation under the set screw. If your application involves heavy shock loads, a keyed bore variant may be more appropriate.
Yes — as long as your belt is an S3M standard (3mm pitch, rounded tooth profile) and is 15mm or 16mm wide, it will mesh correctly with this pulley. Do not use this pulley with HTD 3M belts; although both have a 3mm pitch, the tooth profiles differ and will cause premature wear or skipping.
Both S3M and HTD 3M have a 3mm tooth pitch, but the tooth profiles are different. S3M uses a trapezoidal/rounded tooth designed for lighter loads and precise positioning, while HTD 3M uses a deeper, curvilinear tooth optimized for higher torque. The belts and pulleys are not interchangeable. Always match your belt standard to the pulley standard.
Yes. S3M pulleys are commonly used in 3D printer Z-axis lead screw drives and some extruder geartrains. Select the tooth count that matches your existing drive ratio, and choose a bore that fits your motor shaft or leadscrew diameter. The 16mm width is compatible with standard S3M belts used in desktop 3D printers.
Slide the pulley onto the shaft until it is aligned with your belt path. Use a hex key (Allen wrench) to tighten the set screw against the shaft. For best results, apply a small amount of thread-locking compound to the set screw and ensure the shaft surface is clean and free of oil. If your shaft has a flat, align the set screw with the flat for maximum holding force.
Aluminum alloy offers natural oxidation resistance suitable for most indoor and light-duty outdoor environments. For prolonged exposure to moisture, salt spray, or corrosive chemicals, consider applying a protective coating or selecting a stainless steel alternative. Standard anodizing (where applied) further improves surface corrosion resistance.
