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When a slipping or misaligned pulley costs you a failed print, a crashed axis, or a mis-timed cut, you need a synchronous wheel you can trust. This S2M timing belt pulley is engineered for makers, CNC builders, robotics integrators, and automation engineers who require repeatable, zero-slip power transmission in compact drive trains.
Each pulley is machined from aluminum alloy with an anodized or natural finish and is available in two flange configurations — BF-type (double-flanged) for guided belt retention and K-type (single or no flange) for open-ended belt paths. Tooth counts span 16T to 60T, and bore diameters range from 4 mm (~0.157 in) to 15 mm (~0.591 in), with slot widths of 7 mm or 11 mm to match standard S2M belt widths.
Typical use cases include S2M belt-driven 3D printer X/Y axes, lightweight CNC router gantries requiring low-backlash synchronous drive, and compact robotic joint actuators where a small-pitch 2 mm S2M pulley keeps the drive train tight and responsive.
BF-type offers double flanges for positive belt tracking; K-type provides single or open flange for flexible belt routing in constrained spaces.
Available from 16T to 60T, enabling drive ratios from 1:1 to approximately 3.75:1 within a single product family.
Bore diameters from 4 mm to 15 mm (approx. 0.157–0.591 in) cover common motor shaft sizes including 4, 5, 6, 6.35, 7, 8, 10, 12, 14, and 15 mm.
Lightweight yet rigid aluminum body keeps rotational inertia low — critical for high-acceleration motion control applications.
Conforms to the S2M synchronous belt standard, ensuring interchangeability with off-the-shelf S2M belts from major belt manufacturers.
Bore includes a set-screw flat or keyway slot (depending on variant) for secure shaft locking without adhesives or press-fit tooling.
| Belt Standard | S2M (2 mm pitch) |
|---|---|
| Flange Type | BF-type (double flange) / K-type (single/no flange) |
| Tooth Count | 16T, 20T, 24T, 25T, 30T, 32T, 35T, 36T, 38T, 40T, 45T, 48T, 50T, 55T, 60T |
| Bore Diameter | 4 mm / 5 mm / 6 mm / 6.35 mm / 7 mm / 8 mm / 10 mm / 12 mm / 14 mm / 15 mm |
| Slot Width | 7 mm (S2M-7 belt) or 11 mm (S2M-11 belt) |
| Material | Aluminum alloy |
| Outer Diameter | See variant options |
| Hub Length | See variant options |
| Weight | See variant options |
| Surface Finish | See variant options |
| Shaft Retention | Set screw (M3 or M4, contact us to confirm per variant) |
BF-type pulleys have double flanges on both sides of the tooth profile, which physically guides the belt and prevents it from walking off the pulley — ideal for horizontal or vibration-prone drive systems. K-type pulleys have a single flange or no flange, which is useful when the belt must enter or exit at an angle, or when space constraints prevent a flanged pulley from fitting. For most 3D printer and CNC applications, BF-type is recommended for the driven pulley and K-type for the idler.
The slot width dimension refers to the usable belt-contact width. A 7 mm slot is designed for S2M-7 belts (7 mm wide), and an 11 mm slot is designed for S2M-11 belts (11 mm wide). Using a belt narrower than the slot is generally acceptable but reduces torque capacity; using a belt wider than the slot will cause the belt to ride on the flanges and wear prematurely.
Match the bore diameter to your motor shaft diameter exactly. Common NEMA 17 stepper motors use a 5 mm shaft; NEMA 23 motors typically use an 8 mm shaft; servo motors and DC gearmotors vary widely from 4 mm to 15 mm. If your shaft is imperial (e.g., 1/4 inch = 6.35 mm), select the 6.35 mm bore variant. Always verify with calipers before ordering.
Aluminum alloy pulleys are well-suited for light-to-medium duty S2M applications — the 2 mm pitch belt itself is the limiting factor in torque capacity, not the pulley material. For typical 3D printer, small CNC, and robotics loads, aluminum provides sufficient strength while keeping rotational inertia low. Steel pulleys are generally only needed in high-cycle industrial applications where surface wear over millions of revolutions becomes a concern.
Aluminum alloy naturally forms a thin oxide layer that provides moderate corrosion resistance. Anodized variants offer enhanced protection. For prolonged outdoor or high-humidity exposure, applying a light coat of dry lubricant or corrosion inhibitor to the bore and set-screw area is recommended. The tooth profile itself does not require lubrication when used with standard rubber S2M belts.
Drive ratio = driven pulley teeth ÷ driving pulley teeth. For example, a 40T driven pulley paired with a 20T driving pulley gives a 2:1 reduction (output torque doubles, speed halves). For a 1:1 ratio (common in CoreXY 3D printers), use identical tooth counts on both pulleys. Center distance and belt length must also be calculated — use the formula: Belt length ≈ 2 × center distance + π × (D1 + D2) / 2, where D1 and D2 are the pitch diameters of each pulley.
No. S2M pulleys are designed exclusively for S2M synchronous belts. Although S2M and GT2 both have a 2 mm pitch, their tooth profiles differ — GT2 uses a curvilinear (arc) tooth form while S2M uses a trapezoidal tooth form. Mixing profiles causes poor meshing, increased noise, accelerated wear, and potential belt skipping under load. Always match pulley and belt profiles.
