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When your motion control project demands repeatable, slip-free power transmission, a mismatched or poorly machined pulley becomes the weakest link in the chain. Engineers, hobbyists, and small-shop machinists building CNC routers, 3D printers, robotic arms, or custom conveyor systems need a synchronous wheel that holds tight tolerances without requiring custom tooling or long lead times.
These 3Mod timing belt pulleys feature a 3mm pitch tooth profile machined from aluminum alloy, with tooth counts ranging from 15T to 60T and selectable bore diameters from 3.175mm (~0.125 in) up to 25mm (~0.984 in). Each pulley is finished with an anodized surface to resist wear and corrosion. Overall outer diameter scales with tooth count, typically ranging from approximately 14mm (~0.55 in) for 15T up to approximately 57mm (~2.24 in) for 60T.
Typical use cases include CNC router X/Y axis drives requiring low-backlash synchronous motion, desktop robotic arm joints where precise angular positioning is critical, and DIY automated conveyor or pick-and-place systems where consistent belt engagement across long duty cycles is essential.
Ten tooth count options let you dial in your exact gear ratio for speed reduction or torque multiplication without custom fabrication.
Seventeen bore options — including 3.175mm, 4mm, 5mm, 6mm, 6.35mm, 7mm, 8mm, 10mm, 12mm, 12.7mm, 14mm, 15mm, 16mm, 17mm, 19mm, 20mm, and 25mm — cover the most common shaft standards used in CNC and robotics builds.
The 3M pitch standard ensures positive engagement with matching 3mm pitch timing belts, eliminating belt slip under dynamic loads.
Lightweight aluminum alloy body with anodized finish resists surface oxidation and reduces rotating mass compared to steel alternatives.
Each bore is machined to close tolerance for a secure shaft fit. A set screw or keyway can be added by the user for positive locking on the shaft.
Dimensionally compatible with industry-standard 3M timing belt systems, making these pulleys a direct swap-in for worn or undersized components in existing drive assemblies.
| Pitch | 3mm (3M) |
|---|---|
| Module | 3 Mod |
| Tooth Count (Types) | 15T, 17T, 20T, 22T, 24T, 25T, 30T, 40T, 50T, 60T |
| Bore Diameter | 3.175mm / 4mm / 5mm / 6mm / 6.35mm / 7mm / 8mm / 10mm / 12mm / 12.7mm / 14mm / 15mm / 16mm / 17mm / 19mm / 20mm / 25mm |
| Outer Diameter (approx.) | See variant options (scales with tooth count, typically 14mm–57mm) |
| Material | Aluminum alloy |
| Surface Finish | Anodized |
| Belt Compatibility | 3mm pitch (3M) synchronous timing belt |
| Flange | See variant options |
| Weight (per piece) | See variant options |
The tooth count determines your drive ratio. A smaller pulley (e.g., 15T) on the motor paired with a larger pulley (e.g., 60T) on the driven shaft gives a 4:1 speed reduction and torque multiplication. For direct-drive or 1:1 setups, use matching tooth counts on both pulleys. Calculate your required ratio based on motor RPM and desired output speed before selecting.
Select the bore that matches your shaft diameter exactly. Common shaft sizes: 5mm and 6mm for NEMA 17 stepper motors, 6.35mm (1/4 in) for many US-standard shafts, 8mm for NEMA 23 steppers, and 10mm–25mm for larger servo or gearbox shafts. Measure your shaft with calipers before ordering to avoid a loose or interference fit.
Yes — these pulleys are designed for the 3M (3mm pitch) synchronous belt standard. They will mesh correctly with any 3mm pitch timing belt of a compatible width. Verify that your belt width does not exceed the pulley's flange-to-flange width to prevent belt tracking issues.
Aluminum alloy pulleys offer a favorable strength-to-weight ratio suitable for most CNC, 3D printer, and light robotic applications. For very high torque or heavy industrial duty cycles, steel pulleys may be preferred. For typical DIY and maker applications with belt tensions under a few hundred Newtons, aluminum is the standard choice and reduces rotational inertia.
Anodizing creates an aluminum oxide layer that significantly improves corrosion resistance compared to bare aluminum. These pulleys are suitable for indoor environments and moderate humidity. For prolonged outdoor or salt-spray exposure, additional protective measures (such as a clear coat or periodic lubrication of the bore) are recommended.
The bore is machined to a close tolerance for a snug shaft fit, but for applications with significant torque or reversing loads, adding a set screw (radial grub screw) is strongly recommended to prevent rotational slippage. Keyway machining can be performed by a local machine shop if your shaft uses a keyed interface. Check your shaft and application requirements before assembly.
Yes. These 3M pitch pulleys are widely used in CoreXY and Cartesian 3D printer motion systems, CNC router gantry drives, and laser cutter axis assemblies. Select the tooth count and bore that match your motor shaft and belt specification. The 15T–30T range is most common for printer and router axis drives; larger tooth counts suit slower, higher-torque applications.
