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Slipping belts and inconsistent tension are a constant headache for CNC builders, 3D printer enthusiasts, and automation engineers. These 3M idler and drive pulleys are engineered for builders who need reliable, repeatable belt path control across a wide range of shaft sizes and tooth counts — without having to source multiple incompatible components.
Each pulley is machined from aluminum alloy with a hard-anodized or natural finish and is available in both smooth (idler) and toothed (drive) configurations. Tooth counts range from 15T to 60T, bore diameters from 3 mm (0.12 in) to 17 mm (0.67 in), and belt widths of 6 mm and 10 mm are supported. The set-screw slot width is either 7 mm or 11 mm depending on the selected variant.
Typical use cases include 3M GT2/3M pitch belt tensioning in CoreXY and Cartesian 3D printers, linear axis drives in desktop CNC routers, and compact conveyor or indexing systems in light industrial automation. Long-tail applications such as "3M 20-tooth idler pulley bore 5mm" and "aluminum timing pulley for 10mm belt" are covered across the full variant matrix.
Available from 15T to 60T, covering low-speed high-torque and high-speed precision drive applications in a single product family.
Bore diameters from 3 mm to 17 mm (0.12–0.67 in) accommodate stepper motor shafts, servo shafts, and idler axle bolts without adapters.
Choose smooth-rim idler pulleys for belt tensioning or toothed drive pulleys for positive engagement — both share the same bore and slot dimensions.
Lightweight yet rigid aluminum body keeps rotating mass low, reducing inertia in high-acceleration motion systems such as 3D printer gantries.
Integrated set-screw slot (7 mm or 11 mm width depending on variant) locks the pulley securely to the shaft, preventing slippage under load.
Engineered to the 3 mm tooth pitch standard, ensuring accurate meshing with 3M GT and standard 3M timing belts for repeatable positioning.
| Belt Pitch | 3M (3 mm tooth pitch) |
|---|---|
| Tooth Count | 15T, 16T, 18T, 20T, 24T, 25T, 30T, 32T, 35T, 36T, 40T, 50T, 60T |
| Pulley Type | Without teeth (idler) / With teeth (drive) |
| Compatible Belt Width | 6 mm / 10 mm |
| Bore Diameter | 3 mm – 17 mm (see variant options) |
| Set-Screw Slot Width | 7 mm or 11 mm (see variant options) |
| Material | Aluminum alloy |
| Weight | See variant options |
| Flange | See variant options |
Tooth count determines the pulley pitch diameter and, combined with your motor steps-per-revolution, sets the linear resolution of your drive. Lower tooth counts (15T–20T) give finer resolution and higher torque at the cost of speed; higher counts (40T–60T) increase speed and reduce torque. Match the tooth count to your belt ratio and desired travel-per-step calculation.
"Without teeth" (smooth rim) pulleys are idler pulleys used to guide or tension the belt without driving it — the belt slides over the smooth surface. "With teeth" pulleys are drive pulleys that positively engage the belt teeth for accurate motion transmission. Use smooth idlers on the non-driven side of your belt path and toothed pulleys on the motor shaft.
Standard NEMA 17 stepper motors have a 5 mm output shaft diameter. Select the 5 mm bore variant. If your motor has a flat (D-cut) shaft, ensure the set-screw slot aligns with the flat for a secure grip. For idler axles using M3 or M5 bolts, choose the 3 mm or 5 mm bore accordingly.
These pulleys use a 3M tooth profile (3 mm pitch). Standard GT2 belts have a 2 mm pitch and are not interchangeable. If your system uses 3M pitch belts (3 mm center-to-center tooth spacing), these pulleys are compatible. Always verify the pitch of your existing belt before ordering.
The slot width refers to the width of the set-screw groove machined into the bore. Variants with an 11 mm slot width are designed for 10 mm wide belts, while 7 mm slot variants suit 6 mm wide belts. Selecting the correct slot width ensures the belt tracks centrally on the pulley flange and does not ride up or derail under tension.
Yes. CoreXY and H-bot printers commonly use 3M pitch belts with a mix of toothed drive pulleys on the motor shafts and smooth idler pulleys at the belt path corners. This product covers both roles. Select toothed variants for your X and Y motor shafts and smooth variants for all idler positions, matching the bore to your idler bolt or bearing axle diameter.
Each pulley includes a set-screw slot. Insert an appropriately sized hex key (typically M3 or M4) through the slot and tighten the set screw against the shaft. For D-cut shafts, align the flat with the set screw before tightening to maximize holding force. Apply a small amount of thread-locking compound if vibration is a concern.
