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When your motion system demands exact synchronization, a mismatched or worn pulley becomes the weakest link in the chain. Engineers, CNC builders, and automation hobbyists working with L-series timing belts need a pulley that holds tooth engagement under load without slipping or skipping. These L-type timing belt pulleys are machined to match the 9.525mm (3/8") L-pitch standard, with an AF-type open bore design that accepts a set screw for secure shaft mounting.
Each pulley is machined from aluminum alloy, featuring a 21mm belt-contact width and a precisely cut tooth profile to match standard L-type timing belts. Bore options range from 6mm to 28mm (approximately 0.24" to 1.10"), and tooth counts span from 10T to 40T, giving you the flexibility to dial in your drive ratio. The AF-type designation indicates a through-bore with a set-screw flat, suitable for solid shafts in the specified bore range.
These pulleys are well-suited for CNC router X/Y axis drives, 3D printer extruder and motion systems, light conveyor belt assemblies, and robotic arm joint drives where repeatable positioning and low backlash are required. The L-pitch standard is widely used in applications demanding moderate torque and speed, making these pulleys a practical choice for both prototyping and production builds.
| Belt Type | L-type (3/8" pitch) |
|---|---|
| Pitch | 9.525mm (0.375") |
| Belt Width (max) | 21mm |
| Pulley Face Width | 21mm |
| Tooth Count | 10T, 12T, 14T, 15T, 16T, 17T, 18T, 19T, 20T, 22T, 24T, 25T, 26T, 28T, 30T, 40T |
| Bore Type | AF-type (through bore with set-screw flat) |
| Bore Diameter | 6mm, 6.35mm, 8mm, 10mm, 12mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 22mm, 24mm, 25mm, 28mm |
| Material | Aluminum alloy |
| Outer Diameter | See variant options |
| Hub Diameter | See variant options |
| Flange | See variant options |
| Finish | Natural / anodized (see variant options) |
| Quantity per Order | 1 piece |
The tooth count determines your drive ratio when paired with a second pulley. Divide the driven pulley tooth count by the driving pulley tooth count to get the ratio. For example, a 10T driver paired with a 20T driven pulley gives a 2:1 reduction. Choose a smaller tooth count for higher speed output and a larger tooth count for more torque. For CNC and 3D printer motion axes, 16T–20T is a common starting point.
Measure your motor or gearbox output shaft diameter with calipers before ordering. Common stepper motor shaft sizes are 5mm, 6.35mm (1/4"), and 8mm. Servo motors often use 8mm, 10mm, or larger shafts. The AF-type bore includes a set-screw flat, so the bore must match the shaft diameter exactly — do not select a bore larger than your shaft.
AF-type refers to a through-bore with a machined flat on the inner bore surface. A set screw tightens against this flat to lock the pulley onto the shaft, preventing rotation and axial movement. This is a common and reliable mounting method for timing pulleys in light-to-medium duty applications. Ensure your shaft has a corresponding flat or keyway, or use a shaft with a smooth surface and rely on the set screw friction.
Yes. These pulleys are machined to the L-series pitch standard of 9.525mm (3/8"). They are compatible with any standard L-type timing belt with a width of 21mm or less. Common L-belt widths include 3/8" (9.5mm), 1/2" (12.7mm), 3/4" (19mm), and 1" (25.4mm) — all narrower than 21mm will fit the pulley face. Confirm your belt pitch matches 9.525mm before ordering.
Aluminum alloy pulleys offer a good strength-to-weight ratio for light-to-medium duty power transmission. They are well-suited for CNC routers, 3D printers, robotics, and small conveyor systems. For heavy industrial applications with sustained high torque or abrasive environments, steel pulleys may be more appropriate. The aluminum construction keeps rotational inertia low, which benefits servo and stepper motor responsiveness.
Aluminum alloy naturally forms a thin oxide layer that provides moderate corrosion resistance in typical indoor environments. These pulleys are suitable for workshop, laboratory, and light industrial use. They are not recommended for prolonged exposure to saltwater, strong acids, or highly humid outdoor environments without additional protective coating. For corrosive environments, consider anodized variants or stainless steel alternatives.
Yes — L-type pulleys are widely used in CNC router gantry drives, laser cutter motion systems, and some 3D printer designs that use L-belt drives rather than GT2. Confirm your belt pitch is 9.525mm (L-series), not 2mm (GT2) or 5mm (HTD), as these are not interchangeable. The 21mm face width accommodates most L-belt widths used in these applications.
