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When your DIY drive system slips, squeals, or loses alignment, the culprit is almost always an undersized or poorly machined pulley. Hobbyists, makers, and small-scale machine builders who need a reliable, repeatable belt drive solution will find these aluminum U groove pulleys a direct fix — available in outer diameters from 30mm to 100mm (1.18" to 3.94") with matching bore options to suit your shaft.
Each pulley is machined from aluminum alloy with a single U-shaped groove profile sized for PU round belts. Outer diameters span 30mm, 40mm, 50mm, 60mm, 80mm, and 100mm (1.18"–3.94"); bore sizes range from 5mm to 32mm (0.20"–1.26") depending on the OD selected. Groove width is 8mm across all variants. The lightweight aluminum construction keeps rotational inertia low while providing adequate rigidity for light-to-medium duty applications.
Typical use cases include 3D printer filament drive and idler systems requiring a smooth U-channel, small conveyor belt assemblies for maker projects and lab automation, and custom DIY transmission builds where a compact single-groove aluminum pulley for round belt drives is needed to replace worn or mismatched components.
Six outer diameter options — 30, 40, 50, 60, 80, and 100mm — let you match pulley ratio and belt speed to your specific drive design without custom machining.
Bore sizes from 5mm to 32mm (varies by OD) allow direct shaft mounting across a broad range of motor and axle diameters common in DIY and light industrial builds.
Machined aluminum body delivers a favorable strength-to-weight ratio, keeping rotational inertia low for responsive acceleration in drive systems.
The 8mm-wide U-shaped groove is profiled to seat PU round belts securely, reducing belt walk and maintaining consistent tracking under load.
Single-groove configuration simplifies belt routing in compact drive trains — ideal for 3D printers, small conveyors, and custom transmission assemblies.
Each pulley is machined to consistent dimensional tolerances, ensuring repeatable fit when replacing or pairing pulleys across a multi-stage drive system.
| Material | Aluminum alloy |
|---|---|
| Groove Type | U-groove (single groove) |
| Groove Width | 8mm |
| Outer Diameter (OD) | 30 / 40 / 50 / 60 / 80 / 100mm — See variant options |
| Bore Diameter | 5–32mm (range varies by OD) — See variant options |
| Belt Compatibility | PU round belts |
| Surface Finish | See variant options |
| Item Quantity | 1 pcs per order (default) |
| Weight | See variant options |
The OD determines your pulley ratio and belt surface speed. A larger OD increases belt speed at the same RPM, while a smaller OD gives more torque. Measure the available space in your drive housing and calculate the desired speed ratio between driver and driven pulleys before selecting an OD. Available options are 30, 40, 50, 60, 80, and 100mm.
The bore must match your shaft diameter exactly for a secure fit. Measure your motor or axle shaft with calipers before ordering. Bore options range from 5mm to 32mm depending on the OD selected — check the variant selector for the bore sizes available for your chosen OD. A bore that is too large will cause runout and vibration.
These pulleys are designed for PU (polyurethane) round belts. The U-shaped groove profile with 8mm width seats round-section PU belts securely. Do not use flat belts or V-belts, as the groove geometry is optimized specifically for round belt cross-sections.
Aluminum alloy is well-suited for light-to-medium duty drive applications such as 3D printers, small conveyors, and maker projects. It offers a good strength-to-weight ratio and resists corrosion in typical indoor environments. For heavy-duty industrial applications with high torque or abrasive environments, consider whether a steel pulley would be more appropriate for your load requirements.
Aluminum naturally forms a thin oxide layer that provides moderate corrosion resistance in dry and indoor environments. For applications exposed to moisture, chemicals, or outdoor conditions, additional surface protection (such as anodizing) may be advisable. Contact us if you need clarification on the surface finish of a specific variant.
Yes. The U groove profile works for both driven (powered) and idler (tensioning) pulley positions in a belt drive system. When used as an idler, ensure the bore is fitted with an appropriate bearing or bushing on a fixed shaft to allow free rotation. When used as a driver, secure the pulley to the shaft using a set screw or keyway arrangement appropriate for your torque level.
Use the variant selector on this page — first choose your OD under "Sizes" (which also shows the bore), then confirm the groove width (8mm) and quantity. Not all bore sizes are available for every OD; the selector will only show valid combinations. If you need a specific combination not listed, contact us to confirm availability.
