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When a slipping or mismatched pulley causes your machine to lose synchronization mid-run, the cost in downtime and rework adds up fast. Engineers, CNC builders, and automation hobbyists who need a dependable S8M timing belt pulley with a precise 8mm pitch will find this AF-type drive pulley a straightforward, drop-in solution. The AF (set-screw) bore style makes shaft mounting quick without requiring a keyway, which is ideal for prototyping and retrofit builds alike.
Each pulley is machined from aluminum alloy, featuring a 16mm belt-contact width (tooth width) and an 8mm pitch (distance between tooth centers). Tooth counts range from 10T to 30T, and bore diameters span 6mm to 30mm (approximately 0.24 in to 1.18 in), letting you dial in the exact gear ratio and shaft fit your drive system requires. The outer diameter scales with tooth count — for reference, a 20T pulley measures approximately 50.9mm (2.00 in) OD.
Typical use cases include desktop CNC router X/Y axis drives, 3D printer extruder and motion systems requiring S8M belt compatibility, and light industrial conveyor or indexing table builds where a compact synchronous drive pulley with a selectable bore is needed.
Keyway-free AF bore design clamps directly onto the shaft via set screw, enabling fast installation and easy repositioning without special tooling.
Matches standard S8M timing belts precisely — 8mm center-to-center tooth pitch and 16mm tooth width ensure full belt engagement and minimal backlash.
Thirteen tooth-count options from 10T to 30T let you configure the drive ratio you need without custom machining or compromise.
Bore sizes from 6mm to 30mm (including 12.7mm for imperial shafts) accommodate a wide range of motor and shaft diameters in a single product line.
Lightweight yet rigid aluminum alloy body keeps rotational inertia low while providing the dimensional stability needed for repeatable positioning applications.
Each unit is sold as a single pulley, so you can order exactly the quantity your build requires — no forced multi-packs.
| Belt Type | S8M (Synchronous, 8mm pitch) |
|---|---|
| Pitch | 8 mm |
| Belt Width (Tooth Width) | 16 mm |
| Bore Type | AF-type (set-screw, no keyway) |
| Number of Teeth | 10T, 12T, 14T, 15T, 16T, 18T, 20T, 22T, 24T, 25T, 26T, 28T, 30T |
| Bore Diameter | 6, 8, 10, 12, 12.7, 14, 15, 16, 17, 18, 19, 20, 22, 24, 25, 28, 30 mm |
| Material | Aluminum alloy |
| Outer Diameter | See variant options |
| Flange | See variant options |
| Finish / Color | See variant options |
| Quantity per Order | 1 piece |
The tooth count determines your drive ratio. Divide the driven pulley's tooth count by the driving pulley's tooth count to get the ratio. For example, a 20T driver paired with a 40T driven pulley gives a 2:1 reduction. Smaller tooth counts produce higher speed at the output shaft; larger tooth counts increase torque. Match the tooth count to your required RPM and torque targets before ordering.
Measure your motor or drive shaft diameter with calipers. Select the bore size that matches exactly — for example, a 6.35mm (1/4 in) shaft fits the 6mm bore with light press, while a 12.7mm bore is provided for standard 1/2 in imperial shafts. The AF set-screw design allows minor shaft diameter variation to be compensated, but the bore should not exceed the shaft diameter.
Yes — these pulleys are designed specifically for S8M synchronous timing belts with an 8mm pitch. Confirm that your belt is labeled S8M and has a 16mm width (or narrower, as a wider pulley can run a narrower belt). Do not use with HTD 8M belts; while the pitch is the same, the tooth profile differs and will cause premature wear.
The AF-type bore uses one or two radial set screws that bear directly on the shaft. For light-to-medium duty applications such as CNC motion axes, 3D printer drives, and indexing tables, the clamping force is sufficient. For high-torque or shock-load applications, consider adding a flat on the shaft to give the set screw a positive seat, which significantly increases holding strength.
Aluminum alloy naturally forms a thin oxide layer that resists light corrosion in typical indoor environments. For humid, wet, or mildly corrosive environments, the pulleys can be anodized or coated after purchase. They are not recommended for direct immersion in water or exposure to strong acids or alkalis without additional surface protection.
Yes. S8M pulleys are interchangeable between driving and driven positions. Simply select the appropriate tooth count for each side to achieve your desired ratio. Both pulleys must share the same pitch (8mm) and belt width (16mm) for proper belt tracking.
Both have an 8mm pitch, but the tooth profiles differ. S8M uses a trapezoidal tooth form, while HTD 8M uses a curvilinear (rounded) profile. They are not interchangeable — using an S8M pulley with an HTD 8M belt (or vice versa) will result in poor meshing, noise, and accelerated wear. Always match pulley and belt by both pitch and profile designation.
