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When a slipping or misaligned pulley throws off your CNC router, 3D printer, or robotic axis, every subsequent cut or layer compounds the error. Engineers and makers who need repeatable, backlash-free motion rely on a correctly matched 2GT timing pulley — one that locks onto the shaft without play and meshes cleanly with the belt tooth profile. These K-type pulleys are designed for that exact scenario.
Each pulley is machined from aluminum alloy and features the 2GT (GT2) tooth profile with a 2 mm pitch. The bore diameter ranges from 3 mm to 15 mm (approximately 0.12 in to 0.59 in), and the tooth count spans 14 T to 30 T, giving an outer diameter range of roughly 9 mm to 19 mm (0.35 in to 0.75 in). The belt-contact width is sized for 10 mm wide GT2 belts. Optional keyway widths of 3 mm or 4 mm are available on select bore/tooth combinations for positive torque transmission.
Typical use cases include CNC router X/Y axis drives where tooth-count ratio sets the steps-per-mm, 3D printer CoreXY or Cartesian motion systems requiring matched pulley pairs, and lightweight robotic arm joints where low inertia and dimensional accuracy matter. Long-tail search terms that describe this product: "2GT 20 tooth pulley 5mm bore", "GT2 timing pulley 10mm belt aluminum", "K-type pulley with keyway CNC".
| Belt Type | GT2 / 2GT, 2 mm pitch |
|---|---|
| Belt Width | 10 mm (0.39 in) |
| Number of Teeth | 14 T / 15 T / 16 T / 18 T / 20 T / 22 T / 24 T / 25 T / 26 T / 28 T / 30 T |
| Bore Diameter | 3 mm – 15 mm (see variant options) |
| Keyway Width | Without keyway / 3 mm / 4 mm (see variant options) |
| Material | Aluminum alloy |
| Pulley Type | K-type (flanged) |
| Outer Diameter (approx.) | Varies by tooth count — see variant options |
| Quantity per Pack | 1 pc / 2 pcs / 5 pcs (see variant options) |
| Surface Finish | See variant options |
The tooth count determines your drive ratio and steps-per-mm. For most desktop 3D printers using a standard stepper motor with 1/16 microstepping, a 20-tooth pulley paired with a 2 mm pitch belt gives approximately 80 steps/mm — a common baseline. For CNC routers, match the tooth count on both ends of the belt run to maintain a 1:1 ratio, or use different counts to gear up or down. Smaller tooth counts (14–18 T) suit compact, high-ratio drives; larger counts (24–30 T) are used where higher belt speed or smoother engagement is needed.
A keyway is needed when the pulley must transmit significant torque without slipping on the shaft. If you are relying solely on a set screw, the keyway-less variant is sufficient for light-duty or low-torque applications such as most 3D printer extruder drives. For CNC spindle drives or robotic joints under load, select the 3 mm or 4 mm keyway variant to match your motor shaft's keyway slot. Measure your shaft keyway width before ordering.
These pulleys are designed specifically for 10 mm wide GT2 / 2GT belts with a 2 mm pitch. Using a narrower belt (e.g., 6 mm) will work mechanically but may reduce load capacity and cause the belt to wander laterally. Do not use these pulleys with HTD, T5, or other non-GT2 belt profiles, as the tooth geometry is not compatible.
Aluminum alloy pulleys offer an excellent strength-to-weight ratio for the torque levels typical in CNC routing, 3D printing, and light robotics. They are significantly lighter than steel, which reduces rotational inertia and allows faster acceleration. For very high-torque industrial applications, steel pulleys may be preferred, but for the motion systems these pulleys are designed for, aluminum alloy is the standard material choice.
Aluminum alloy naturally forms a thin oxide layer that provides moderate corrosion resistance in typical indoor workshop or lab environments. For applications exposed to moisture, cutting fluids, or outdoor conditions, consider applying a light coat of machine oil or selecting an anodized variant if available. Avoid prolonged contact with strong acids or alkalis.
Use a digital caliper to measure the outer diameter of your motor shaft at the point where the pulley will sit. Common NEMA 17 stepper motor shafts are 5 mm; NEMA 23 shafts are typically 6.35 mm (1/4 in). Servo motors and DC motors vary widely — always measure before ordering. The bore should match the shaft diameter exactly; a loose fit will cause runout and vibration.
Yes. These K-type pulleys work with both open-loop (cut-to-length) and closed-loop (endless) GT2 belts of 10 mm width. For closed-loop systems, ensure the belt loop length is compatible with the center distance between your two pulleys. The pulley flanges help keep the belt tracking correctly on the pulley face.
