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When your belt-driven system loses tension or runs off-track, the culprit is often a worn or mismatched idler pulley. Engineers, CNC builders, and 3D printer enthusiasts who demand consistent, low-vibration motion need a smooth idler pulley that holds tolerance under continuous load. This 5M20T smooth idler pulley with a 6mm bore is engineered for exactly that role — keeping your 15mm wide timing belt aligned and tensioned without introducing tooth engagement noise.
This idler pulley is machined to suit the 5M (HTD 5M) belt profile with 20 teeth equivalent pitch diameter. The bore diameter is 6mm, accepting standard 6mm shafts or bearings. The pulley body is typically 28–32mm in outer diameter and compatible with 15mm wide belts. Constructed from aluminum alloy with a smooth, anodized or natural finish, it offers a lightweight yet rigid running surface that minimizes belt wear.
Typical applications include CNC router belt tensioning systems, 3D printer X/Y axis idler positions, automated conveyor tensioners, and DIY linear motion rigs where a smooth idler timing belt pulley for 15mm HTD belt is required. Its compact form factor also suits robotic arm drive trains and laser cutter gantry systems.
No teeth on the running face — eliminates engagement noise and reduces belt fatigue when used as a tensioner or redirector in HTD 5M drive systems.
Accepts 6mm shafts or flanged bearings directly, making installation straightforward on most CNC, 3D printer, and DIY motion platforms without custom machining.
Flanged profile keeps 15mm wide HTD 5M belts centered and prevents lateral drift during high-speed or high-load operation.
Lightweight aluminum body reduces rotational inertia for faster acceleration response while maintaining the rigidity needed for sustained tension loads.
20-tooth equivalent pitch diameter ensures the belt wraps with the correct bend radius, protecting belt integrity and extending service life in continuous-duty applications.
Dimensionally consistent with standard 5M20T idler pulleys used across popular open-source CNC and 3D printer designs — swap in without redesigning your tensioner bracket.
| Belt Profile | HTD 5M |
|---|---|
| Number of Teeth (Pitch Equiv.) | 20T |
| Belt Width | 15mm (0.59 in) |
| Bore Diameter | 6mm (0.236 in) |
| Outer Diameter | See variant options |
| Flange Outer Diameter | See variant options |
| Hub Width | See variant options |
| Material | Aluminum Alloy |
| Surface | Smooth (no teeth) |
| Finish | Natural / Anodized (See variant options) |
| Quantity | 1 piece |
| Weight | Approx. 30–70g (1.1–2.5 oz) |
This pulley is designed for the HTD 5M timing belt profile — a 5mm pitch, rounded tooth profile. It is not compatible with T5, GT2, or other belt profiles. Always confirm your belt's pitch before ordering.
This is a smooth idler pulley — the running surface has no teeth. It is used to tension or redirect the belt, not to drive it. If you need a toothed drive pulley, please check our 5M20T drive pulley listings.
The bore is 6mm in diameter, fitting standard 6mm shafts or 6mm outer-diameter flanged bearings (such as F686ZZ). If your shaft is a different diameter, please select the appropriate bore variant or contact us to confirm availability.
Check your machine's belt specification (must be HTD 5M, 15mm wide) and idler shaft diameter (must be 6mm). This pulley is dimensionally compatible with many popular open-source designs including those using 15mm wide 5M belts on 6mm idler shafts. If unsure, share your machine model and we can advise.
Aluminum alloy provides a good strength-to-weight ratio for idler pulley applications. For most CNC, 3D printing, and light industrial tensioning duties, aluminum idler pulleys perform reliably. For very high-load or high-temperature environments, contact us to discuss material options.
Please refer to the product variant description or contact us to confirm whether a bearing is pre-installed. Some configurations ship with a flanged bearing inserted; others are bare bore for use with your own bearing or shaft. Check the variant title for clarification.
Yes — this is a direct drop-in replacement for standard 5M20T smooth idler pulleys with a 6mm bore and 15mm belt width. Verify the outer diameter and flange dimensions match your tensioner bracket before installing.
