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When your CNC router, 3D printer, or linear motion system loses belt tension or develops unwanted slack, the culprit is often a missing or worn idler pulley. Engineers and makers who rely on GT2 belt-driven motion need a reliable 2GT idler pulley that fits precisely, runs quietly, and holds alignment under continuous load. These 2GT idler pulleys are designed for exactly that role — keeping your drive belt taut and your motion system accurate.
Each pulley is machined from aluminum alloy with a pre-installed bearing for smooth rotation. Two styles are available: Smooth Idler Drive (flat outer rim, for belt back-side tensioning) and Teeth Idler Drive (toothed outer rim, for meshing with the belt tooth profile). Tooth counts range from 16 to 40 teeth; bore diameters span 3 mm (~0.12 in) to 8 mm (~0.31 in). Compatible belt widths are 6 mm and 10 mm, matching standard GT2 / 2GT belt profiles.
Typical use cases include CoreXY and Cartesian 3D printer belt path routing, CNC router X/Y axis tensioning, laser engraver carriage systems, and compact robotics or automation belt drives where a low-profile idler is required to redirect or tension a 2GT timing belt.
Choose Smooth Idler Drive for back-side belt tensioning or Teeth Idler Drive for tooth-engaged routing — both available across the full size range.
Tooth counts from 16 T to 40 T and bore diameters from 3 mm to 8 mm let you match the exact shaft and belt geometry of your build.
Lightweight yet rigid aluminum construction keeps rotational inertia low while maintaining dimensional stability under belt tension loads.
Each pulley ships with a bearing already seated, enabling immediate installation on your idler shaft without additional hardware sourcing.
Available for both 6 mm and 10 mm wide GT2 belts, covering the two most common widths used in desktop CNC and 3D printing platforms.
Standard 2GT tooth profile and common bore sizes make these a direct drop-in replacement for worn or missing idlers in existing motion systems.
| Belt Profile | 2GT / GT2 |
|---|---|
| Drive Style | Smooth Idler Drive / Teeth Idler Drive (see variant options) |
| Tooth Count | 16 T, 20 T, 25 T, 30 T, 36 T, 40 T (see variant options) |
| Belt Width | 6 mm or 10 mm (see variant options) |
| Bore Diameter | 3 mm / 4 mm / 5 mm / 6 mm / 7 mm / 8 mm (see variant options) |
| Body Material | Aluminum alloy |
| Bearing | Pre-installed (type: see variant options) |
| Outer Diameter | See variant options |
| Flange | See variant options |
| Finish | Natural anodized / machined aluminum |
| Quantity per Order | 1 pc or 2 pcs (see variant options) |
Use Smooth Idler Drive when the pulley contacts the back (flat) side of the belt — common for tensioning in CoreXY and Cartesian printers. Use Teeth Idler Drive when the pulley engages the toothed face of the belt, such as in path-routing configurations where the belt wraps around the pulley teeth for positive engagement.
Match the tooth count to your existing belt path geometry. Smaller tooth counts (16 T, 20 T) are common in compact printer frames where tight bend radii are needed. Larger counts (30 T, 36 T, 40 T) are used where the belt path allows a larger pulley diameter, reducing belt stress. Check your printer or CNC documentation for the recommended idler tooth count.
The bore diameter must match your idler shaft or bolt diameter. Common shaft sizes are 3 mm, 4 mm, 5 mm, and 6 mm for desktop motion systems; 7 mm and 8 mm are used in heavier-duty or larger-format machines. Measure your existing shaft or check your BOM before ordering.
Yes — both belt widths are available. The belt width is specified in the Size variant option (e.g., "20 Teeth-Belt 6mm-Bore 3mm" uses a 6 mm belt; "20 Teeth-Belt 10mm-Bore 3mm" uses a 10 mm belt). Select the variant that matches your belt width.
Yes, each pulley ships with a bearing pre-installed. The bearing type is a standard radial ball bearing sized to the bore diameter. This allows the pulley to spin freely on a fixed shaft or bolt. No additional bearing sourcing is required for standard installations.
Yes. CoreXY systems commonly use both smooth and toothed idlers to route the two belts through the gantry. Smooth idlers handle back-side belt contact at direction-change points, while toothed idlers are used where the belt tooth face must be engaged. Select the appropriate style and tooth count based on your CoreXY design's idler positions.
The outer diameter of a 2GT pulley is determined by its tooth count: OD ≈ (tooth count × 2 mm pitch) / π. For example, a 20-tooth pulley has an OD of approximately 12.7 mm (~0.50 in). If you need an exact OD for your design, contact us to confirm before ordering.
