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When a slipping or mismatched pulley derails your CNC router, 3D printer, or conveyor build mid-run, the cost is more than time — it's accuracy and repeatability. The S3M AF-type timing belt pulley is engineered for makers, machine builders, and automation engineers who need a reliable, drop-in synchronous drive component that holds position under load.
Each pulley is machined from aluminum alloy with an anodized finish, featuring an S3M tooth profile (3mm pitch, ~1.14mm tooth height) and a fixed 11mm belt width (C11). Available in 18 to 80 teeth, with bore options from 8mm to 25mm (0.31" to 0.98") and matching keyway dimensions from 3×1.4mm up to 8×3.3mm. The AF-type flange configuration keeps the belt tracked without additional guides.
Typical applications include CNC axis drives requiring sub-millimeter positioning, 3D printer X/Y motion systems, light-duty conveyor and indexing tables, and robotics joint actuators where a compact synchronous belt pulley with keyway is needed for shaft locking.
Double-flange construction keeps the S3M belt centered on the pulley face, reducing lateral drift in high-speed CNC and automation drives.
Select from 18 to 80 teeth to dial in your exact gear ratio for stepper or servo motor drives without custom machining.
Bores from 8mm to 25mm with matched keyways (3×1.4mm to 8×3.3mm) for secure shaft engagement and zero-slip torque transmission.
Lightweight yet rigid aluminum body keeps rotational inertia low — ideal for rapid direction changes in CNC and pick-and-place systems.
Standardized C11 flange width ensures direct compatibility with S3M belts across common motion control platforms.
Precisely cut S3M tooth geometry delivers consistent pitch engagement, minimizing backlash and maintaining positional accuracy over long duty cycles.
| Belt Profile | S3M (Synchronous, 3mm pitch) |
|---|---|
| Pitch | 3mm (0.118") |
| Tooth Height | Typically 1.14mm (0.045") |
| Belt Width Compatibility | 11mm (C11 flange) |
| Number of Teeth | 18T – 80T (see variant options) |
| Bore Diameter | 8mm – 25mm (see variant options) |
| Keyway Dimensions | 3×1.4mm / 4×1.8mm / 5×2.3mm / 6×2.8mm / 8×3.3mm (see variant options) |
| Pulley Type | AF-type (double flange) |
| Material | Aluminum alloy |
| Finish | Anodized |
| Quantity per Order | 1 piece |
| Weight | See variant options |
The tooth count determines your drive ratio. Divide the driven pulley teeth by the driver pulley teeth to get the ratio. For example, a 40T driven pulley paired with a 20T driver gives a 2:1 reduction. For CNC and 3D printer axes, matching tooth counts on both ends gives a 1:1 ratio for direct motor-to-axis mapping. Select based on your required speed and torque trade-off.
Measure your motor or drive shaft diameter precisely with calipers. Available bores are 8mm, 10mm, 12mm, 12.7mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, and 25mm. Choose the bore that matches your shaft exactly — the keyway provides the locking mechanism, so a snug bore fit is essential for accurate torque transfer.
Keyway dimensions follow standard DIN 6885 sizing relative to bore diameter. As a guide: 8–10mm bores typically use 3×1.4mm keyways; 10–12mm bores use 4×1.8mm; 12–17mm bores use 5×2.3mm; 18–22mm bores use 6×2.8mm; and 25mm bores use 8×3.3mm. The exact keyway is shown in the variant name — always verify against your shaft's existing keyway slot.
Yes. This pulley is designed for S3M profile timing belts with a 3mm pitch. It is compatible with both open-end S3M belt stock and closed-loop S3M belts, provided the belt width is 11mm (C11). Do not use with S2M (2mm pitch) or HTD 3M belts, as the tooth profiles are not interchangeable.
The aluminum alloy construction provides a good strength-to-weight ratio suitable for light to medium duty CNC, 3D printing, and automation applications. For continuous high-torque industrial drives or environments with heavy shock loads, verify the pulley's rated torque against your application requirements. The keyway connection significantly increases torque capacity compared to set-screw-only designs.
The anodized aluminum finish provides good resistance to oxidation and mild environmental exposure. It is suitable for indoor workshop, laboratory, and light industrial environments. For outdoor or high-humidity applications, consider applying a light protective coating to the bore and keyway areas, which are bare metal after machining.
Yes. S3M pulleys are widely used in DIY CNC routers, laser cutters, and 3D printer motion systems. Select a bore that matches your stepper motor shaft (commonly 5mm, 6.35mm, or 8mm — note: 5mm and 6.35mm are not available in this listing; 8mm is the smallest bore offered here). Pair with an S3M belt of matching width for a complete synchronous drive system.
The pitch diameter (PD) of an S3M pulley is calculated as: PD = (Number of Teeth × Pitch) ÷ π. For example, a 30T pulley: PD = (30 × 3) ÷ 3.1416 ≈ 28.65mm. Use this to calculate center distances and belt lengths for your drive layout.
