Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
When a slipping or mismatched pulley derails your CNC router, 3D printer, or automation rig mid-job, the frustration is real. Engineers, makers, and robotics builders who need repeatable, slip-free power transmission rely on S3M timing belt pulleys that match their belt pitch exactly. These S3M pulleys are designed for anyone running 3M-pitch synchronous belts who demands dimensional accuracy and consistent tooth engagement across every cycle.
Each pulley is machined from aluminum alloy with a natural silver finish. The tooth profile follows the S3M (3mm pitch) standard, with a belt-contact width of 16mm (0.63 in). Available tooth counts range from 12T to 40T, and bore options span 5mm to 20mm (0.20–0.79 in), covering the most common shaft sizes used in motion-control applications. Two hub styles are offered: K-type (standard hub with set-screw) and BF-type (flanged hub with set-screw), sold individually (1 piece per order).
Typical use cases include CNC router X/Y axis drives, desktop 3D printer extruder and gantry assemblies, light-duty conveyor and indexing systems, and DIY robotic arm joint actuators — all applications where an S3M timing belt pulley with a 3mm pitch and 16mm width delivers the tooth count and bore flexibility needed for a clean, rattle-free drive.
Available from 12T to 40T, letting you dial in the exact gear ratio your drive system requires without compromise.
Bore options from 5mm to 20mm (0.20–0.79 in) accommodate a broad range of motor and shaft diameters common in CNC and robotics builds.
Choose a standard K-type hub or a flanged BF-type hub — both secured with a set-screw for firm, repeatable shaft clamping.
Tooth geometry conforms to the S3M standard, ensuring smooth meshing with any S3M-compatible timing belt and minimizing backlash.
Lightweight yet rigid aluminum alloy body keeps rotational inertia low while withstanding the cyclic loads of continuous-duty motion systems.
Each order ships as 1 piece, so you can source exactly the quantity you need for single-axis or multi-axis drive configurations.
| Belt Standard | S3M (Synchronous 3M) |
|---|---|
| Pitch | 3mm (0.118 in) |
| Belt Width | 16mm (0.63 in) |
| Number of Teeth | 12T – 40T (see variant options) |
| Bore Diameter | 5 / 6 / 6.35 / 7 / 8 / 10 / 12 / 12.7 / 14 / 15 / 16 / 17 / 18 / 19 / 20mm (see variant options) |
| Hub Style | K-type (standard) or BF-type (flanged) — see variant options |
| Material | Aluminum alloy |
| Finish | Natural silver (uncoated) |
| Fastening Method | Set-screw |
| Quantity per Order | 1 piece |
| Outer Diameter | See variant options |
| Weight | See variant options |
The tooth count determines your drive ratio. Divide the driven pulley teeth by the driver pulley teeth to get the ratio. For example, a 20T driver paired with a 40T driven pulley gives a 2:1 reduction. Match the tooth count to your required speed and torque output, and ensure both pulleys share the same S3M 3mm pitch.
Measure your motor or drive shaft diameter precisely with calipers. Select the bore that matches — common sizes include 5mm, 6mm, 6.35mm (1/4 in), 8mm, 10mm, 12mm, and larger. The set-screw secures the pulley once installed, so the bore should match the shaft diameter closely rather than being oversized.
K-type pulleys have a standard cylindrical hub with a set-screw for shaft clamping — suitable for most inline drive applications. BF-type pulleys add a flange on the hub, which helps retain the belt laterally and is preferred in applications where belt walk-off is a concern, such as high-speed or vertically oriented drives.
Yes. These pulleys are machined to the S3M tooth profile standard (3mm pitch), so they mesh with any S3M-compatible synchronous timing belt of 16mm width. Confirm your belt is labeled S3M or 3M pitch before ordering — do not use with HTD 3M or GT2 3mm belts, as those have different tooth profiles.
Aluminum alloy pulleys handle the cyclic loads of typical CNC, 3D printing, and light automation applications reliably. For heavy industrial loads or high-torque applications exceeding the belt's rated tension, consider whether a steel pulley is more appropriate. For most maker and engineering projects, aluminum provides an excellent balance of strength and low rotational inertia.
Yes. This listing covers the pulley only (1 piece per order). You will need to source an S3M timing belt of 16mm width separately. When selecting belt length, account for center distance, both pulley pitch diameters, and any tensioner travel in your design.
Absolutely. S3M pulleys are widely used in desktop CNC routers, laser cutters, and 3D printers that use 3mm-pitch belt drives. Verify that your machine's belt is S3M-compatible and that the bore matches your stepper motor shaft diameter (commonly 5mm or 6.35mm for NEMA 17/23 motors).
