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When a slipping or misaligned drive pulley brings your build to a halt, you need a replacement you can trust. This XL timing pulley is designed for engineers, makers, and machine builders who require accurate, repeatable motion transfer without backlash. Whether you are retrofitting a CNC router, upgrading a 3D printer axis, or building a custom conveyor, the right tooth count and bore size make all the difference.
Each pulley is machined from aluminum alloy and features a trapezoid XL tooth profile (pitch: 5.08 mm / 0.200 in) with a precision keyway bore. Available in 9 tooth counts — 15T, 16T, 18T, 20T, 22T, 24T, 25T, 30T, and 40T — and bore diameters ranging from 8 mm (0.31 in) to 25 mm (0.98 in), with matching keyway dimensions from 3×1.4 mm up to 8×3.3 mm. Sold in quantities of 1, 2, or 3 pieces per order.
Typical use cases include XL belt-driven CNC axis systems, stepper motor drive trains in desktop 3D printers, light-duty conveyor and indexing table drives, and robotics joint actuators requiring low-backlash synchronous motion. The keyway bore ensures positive torque transmission without relying solely on set screws, making this XL timing pulley a reliable choice for applications where shaft slip is not acceptable.
| Belt Pitch | XL — 5.08 mm (0.200 in) |
|---|---|
| Tooth Profile | Trapezoid (XL standard) |
| Available Tooth Counts | 15T, 16T, 18T, 20T, 22T, 24T, 25T, 30T, 40T |
| Bore Diameter Range | 8 mm – 25 mm (0.31 in – 0.98 in) |
| Keyway Dimensions (by bore) | 8–10 mm bore: 3×1.4 mm; 10–16 mm bore: 4×1.8 mm or 5×2.3 mm; 17–20 mm bore: 6×2.8 mm; 25 mm bore: 8×3.3 mm |
| Material | Aluminum alloy |
| Finish | Natural / anodized (see variant options) |
| Outer Diameter | See variant options |
| Hub Width | See variant options |
| Pack Quantity | 1 Pcs / 2 Pcs / 3 Pcs (select above) |
| Weight (per piece) | See variant options |
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 drive pulley paired with a 40T driven pulley gives a 2:1 reduction. Match the tooth count to your required speed or torque ratio, and ensure both pulleys share the same XL pitch (5.08 mm).
Measure your motor or drive shaft diameter precisely with calipers. Select the bore that matches your shaft diameter exactly — the keyway provides the positive drive, so a snug fit is essential. Available bores range from 8 mm to 25 mm. If your shaft is imperial (e.g., 1/2 in = 12.7 mm), select the 12.7 mm bore option where available.
The keyway is a rectangular slot machined into the bore that accepts a matching key on the shaft. This key transmits torque mechanically, preventing the pulley from spinning on the shaft under load. The keyway dimension (e.g., 3×1.4 mm, 5×2.3 mm) refers to the width × depth of the slot. Always match the keyway to your shaft's key specification.
Yes. These pulleys use the standard XL trapezoid tooth profile with a 5.08 mm (0.200 in) pitch, which is compatible with all standard XL synchronous timing belts. Verify that your belt's tooth profile is XL (not GT2, HTD, or T5) before ordering. Belt width must also be appropriate for the pulley flange width.
The aluminum alloy construction provides a good strength-to-weight ratio suitable for typical stepper and small servo motor applications in CNC and 3D printing. For very high-torque industrial drives, verify the pulley's rated torque against your motor's output. The keyway bore significantly increases torque capacity compared to set-screw-only designs.
Aluminum alloy naturally forms a thin oxide layer that provides moderate corrosion resistance in typical indoor workshop and machine environments. For humid or outdoor environments, consider applying a light coating of machine oil or selecting an anodized variant if available. Avoid prolonged exposure to salt spray or strong acids.
You can order 1, 2, or 3 pieces per variant. Select the Amounts option above to choose your preferred quantity. This flexibility lets you buy a single replacement pulley, a matched pair for a dual-axis machine, or a set of three for a multi-axis build or to keep a spare.
Some bore sizes (e.g., 10 mm, 12 mm) are available with two different keyway dimensions. The 4×1.8 mm keyway follows one standard (DIN 6885 series), while the 5×2.3 mm follows a slightly larger key standard. Match the keyway to the key already cut on your shaft. If you are cutting a new key, either standard works — just be consistent between shaft and pulley.
