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When a slipping or mismatched pulley derails your CNC router, 3D printer, or automation rig mid-job, the cost is more than downtime — it's lost precision and wasted material. Engineers, makers, and small-batch manufacturers who demand repeatable motion control need a drive pulley that holds its pitch under load. These XL aluminium timing belt drive pulleys are machined to XL belt standards and available in three hub types (AF, BF, and K) to suit a wide range of shaft and belt configurations.
Each pulley is machined from aluminium alloy, keeping rotating mass low while maintaining dimensional stability. The belt-contact width is 10mm (approximately 0.39"), with a standard XL pitch of 5.08mm (0.2"). Tooth counts range from 10 to 40T, and bore sizes span 4mm to 25mm (approximately 0.16" to 0.98"), with select variants offering keyway bores (4mm, 5mm, or 6mm keyway) for positive shaft engagement.
Typical use cases include XL belt-driven CNC axis drives, stepper motor pulleys for desktop automation, timing belt tensioner replacements, and custom robotics joint drives where low backlash and consistent pitch are required. Long-tail applications include DIY laser cutter X/Y drives, pick-and-place machine actuators, and belt-driven linear rail systems.
Machined to XL belt standard for accurate tooth engagement and minimal backlash across the full 10–40 tooth range.
Bore options from 4mm to 25mm (0.16"–0.98") cover most stepper, servo, and DC motor shaft sizes used in CNC and automation builds.
Select BF variants include keyway bores (4mm, 5mm, or 6mm) for positive shaft locking — ideal for high-torque or reversing-load applications.
Type AF (no flange), Type BF (single flange), and Type K (double flange) allow belt retention to be matched to your drive geometry and belt tracking requirements.
Aluminium alloy body reduces rotational inertia compared to steel equivalents, supporting faster acceleration in servo and stepper-driven axes.
Choose from 10T, 12T, 15T, 16T, 18T, 20T, 24T, 25T, 30T, and 40T to dial in your drive ratio for speed or torque optimization.
| Belt Type | XL (Extra Light) |
|---|---|
| Belt Pitch | 5.08mm (0.2") |
| Belt Width | 10mm (0.39") |
| Tooth Count | 10T, 12T, 15T, 16T, 18T, 20T, 24T, 25T, 30T, 40T |
| Hub Type | Type AF (no flange) / Type BF (single flange) / Type K (double flange) |
| Bore Diameter | 4mm – 25mm (0.16" – 0.98"); keyway options: 4mm, 5mm, 6mm |
| Material | Aluminium alloy |
| Finish | See variant options |
| Set Screw | See variant options |
| Outer Diameter | See variant options |
| Hub Length | See variant options |
| Quantity per Order | 1 pc |
Tooth count determines your drive ratio. A smaller driving pulley paired with a larger driven pulley reduces speed and increases torque. For CNC routers and 3D printers, 20T is a common starting point. Calculate your required ratio by dividing the driven pulley tooth count by the driving pulley tooth count. Match the tooth count to your belt length and center distance to avoid belt tension issues.
Type AF has no flanges on either side of the pulley — the belt is guided by the drive system geometry. Type BF has a single flange on one side to help retain the belt laterally. Type K has flanges on both sides for maximum belt containment, which is useful in applications where belt tracking cannot be guaranteed by alignment alone. Choose based on your belt width, tension, and whether your system has other belt-guiding features.
Measure your motor or drive shaft diameter precisely with calipers. Select the bore size that matches your shaft diameter. For a secure fit without play, the bore should match the shaft closely. If your shaft has a flat or keyway, select a keyway bore variant (available in 4mm, 5mm, or 6mm keyway) to prevent rotational slipping under load. Avoid selecting a bore larger than your shaft diameter.
Yes. These pulleys are machined to the XL timing belt standard with a 5.08mm (0.2") pitch and are designed for 10mm-wide XL belts. They will mesh correctly with any standard XL open-end or closed-loop belt of the same pitch. Confirm your belt width is 10mm before ordering — XL belts also come in wider widths (e.g., 3/8" or 1/2") that require different pulleys.
For light-duty or low-torque applications (e.g., 3D printer extruder drives), a plain bore with a set screw is typically sufficient. For higher-torque applications, reversing loads, or where shaft slippage would cause positioning errors (e.g., CNC axis drives), a keyway bore provides a more positive mechanical connection and is recommended. Keyway variants are available for select BF tooth counts with 4mm, 5mm, and 6mm keyway widths.
These pulleys are machined from aluminium alloy. Aluminium offers a good balance of low weight, machinability, and corrosion resistance for indoor automation and CNC environments. The lower density compared to steel reduces rotational inertia, which benefits systems with frequent direction changes or high acceleration requirements. For outdoor or high-humidity environments, consider whether additional surface protection is needed for your specific conditions.
Yes. XL pulleys are widely used in desktop CNC machines, laser cutters, and some 3D printer designs — particularly those using XL belts rather than the more common GT2 belt. Verify that your machine uses XL (5.08mm pitch) belts and 10mm belt width before ordering. Common tooth counts for these applications are 20T and 25T for the driving pulley, depending on your desired steps-per-mm and motor resolution.
