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When your 3D printer skips steps, your CNC router loses position, or your robotics drive train slips under load, the culprit is often a poorly fitted pulley. Engineers, makers, and machine builders who demand repeatable, slip-free motion need a GT2 timing belt pulley that fits their shaft exactly — not one that requires shimming or loctite to stay put. These GT2 BF-type pulleys are designed for builders who refuse to compromise on dimensional accuracy.
Each pulley is machined from aluminum alloy and features the GT2 tooth profile (2 mm pitch) with a 7 mm tooth width, available in 40T, 42T, and 44T tooth counts. Bore diameters range from 5 mm to 15 mm (approximately 0.197 in to 0.591 in), with optional keyway widths of 3 mm, 4 mm, or 5 mm for positive shaft locking. The BF-type flange design keeps the belt tracking true under lateral load.
Typical use cases include GT2 belt-driven 3D printer axes (X/Y gantry replacement pulleys), CNC router spindle drive systems requiring 40–44 tooth reduction ratios, and custom robotics or automation rigs where a keyed shaft connection eliminates rotational slip during high-torque reversals.
Three tooth counts let you dial in the exact drive ratio your motion system needs — from compact 40T for tight belt runs to 44T for smoother low-speed torque delivery.
Dual flanges on both sides of the tooth profile keep the GT2 belt centered and prevent lateral walk-off, even during rapid direction changes on 3D printer gantries.
Nine bore diameter options (5, 6, 6.35, 8, 10, 12, 12.7, 14, 15 mm) cover NEMA stepper shafts, servo motor shafts, and standard metric/imperial rod diameters in one product line.
Select 3 mm, 4 mm, or 5 mm keyway variants to mechanically lock the pulley to a keyed shaft — eliminating rotational slip under high-torque or reversing loads without relying on set screws alone.
Lightweight yet rigid aluminum alloy body keeps rotational inertia low for fast acceleration on CNC and 3D printer axes while resisting deformation under belt tension.
Available in 1-piece or 2-piece packs so you can stock exactly what your build requires — whether replacing a single worn pulley or outfitting a dual-axis gantry in one order.
| Tooth Profile | GT2 (2 mm pitch) |
|---|---|
| Tooth Width | 7 mm |
| Number of Teeth | 40T / 42T / 44T (see variant options) |
| Pulley Type | BF-type (flanged both sides) |
| Bore Diameter | 5 / 6 / 6.35 / 8 / 10 / 12 / 12.7 / 14 / 15 mm (see variant options) |
| Keyway Width | Without keyway / 3 mm / 4 mm / 5 mm (see variant options) |
| Material | Aluminum alloy |
| Compatible Belt | 2GT / GT2 timing belt, 6–7 mm width |
| Outer Diameter (approx.) | See variant options |
| Quantity per Pack | 1 pc or 2 pcs (see variant options) |
The tooth count determines your drive ratio when paired with a pinion pulley. A 40T pulley gives a slightly higher belt speed for the same motor RPM, while 44T provides more torque multiplication. For most GT2 3D printer X/Y axes, 20T pinion + 40T driven pulley is common. If you are replacing an existing pulley, match the tooth count exactly to maintain your steps-per-mm calibration.
Standard NEMA 17 stepper motors have a 5 mm output shaft. Select the 5 mm bore option. If your motor has a D-cut or flat on the shaft, the without-keyway variant with a set screw is typically sufficient. For a fully keyed shaft, check your motor's keyway spec before selecting a keyway width.
For light-duty or low-torque applications such as 3D printer belt drives, a set screw on a D-shaft or smooth shaft is usually adequate. For CNC routers, robotics, or any application with frequent direction reversals or high torque, a keyed connection (3 mm, 4 mm, or 5 mm keyway) provides a positive mechanical lock that prevents rotational slip even if the set screw loosens over time.
Yes. These pulleys are designed for the GT2 / 2GT tooth profile with a 2 mm pitch. They are compatible with standard open-loop GT2 timing belts and closed-loop GT2 belts in 6 mm or 7 mm width. The 7 mm tooth width on this pulley accommodates both belt widths without overhang issues.
BF-type pulleys have flanges on both sides of the tooth section. These flanges act as guides that keep the timing belt from sliding off laterally during operation. This is especially important on long belt runs, high-speed axes, or any setup where the belt is not perfectly aligned. If your application has precise belt alignment and short belt spans, a no-flange pulley may work, but BF-type is the safer choice for most builds.
Yes. The 40–44 tooth range and aluminum alloy construction make these pulleys suitable for CNC router and laser cutter belt-drive axes. For CNC applications with higher belt tension, we recommend selecting a keyway variant to ensure the pulley does not slip on the motor shaft under cutting loads. Confirm the bore diameter matches your motor or drive shaft before ordering.
Yes. 6.35 mm is equivalent to 1/4 inch and 12.7 mm is equivalent to 1/2 inch. These bore sizes are included specifically for builders using imperial-dimensioned shafts common in North American CNC and robotics hardware. All other bore options (5, 6, 8, 10, 12, 14, 15 mm) are standard metric sizes.
