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When your CNC router skips steps or your 3D printer loses positional accuracy, the culprit is often a mismatched or worn timing pulley. Engineers, makers, and machine builders who demand repeatable, backlash-free motion need a pulley that fits precisely and holds up under continuous load. These GT2 2GT timing belt pulleys are designed for exactly that — delivering consistent tooth engagement across a wide range of tooth counts and bore sizes.
Each pulley features a GT2 2GT tooth profile machined from aluminum alloy, with a uniform belt width of 7mm (0.28 in). Tooth counts span from 28T to 58T, and through-hole bore diameters range from 4mm to 15mm (0.16–0.59 in), including 6.35mm (1/4 in) and 12.7mm (1/2 in) imperial options. Keyway variants (K 3mm, K 4mm, K 5mm) are available on select bore sizes for positive shaft locking without set-screw slippage.
Typical applications include open-loop CNC routing machines requiring precise X/Y axis drive, FDM 3D printer extruder and motion systems using GT2 belts, and lightweight robotic arm joints or linear actuator assemblies where low backlash timing pulleys are critical for repeatability.
| Tooth Profile | GT2 / 2GT |
|---|---|
| Pitch | 2mm |
| Belt Width | 7mm (0.28 in) |
| Tooth Count | 28T, 30T, 32T, 34T, 35T, 36T, 38T, 40T, 42T, 44T, 45T, 46T, 48T, 50T, 52T, 54T, 56T, 58T |
| Through-Hole Bore | 4mm, 5mm, 6mm, 6.35mm, 8mm, 10mm, 12mm, 12.7mm, 14mm, 15mm |
| Keyway Options | K 3mm, K 4mm, K 5mm (available on select bore sizes) |
| Material | Aluminum alloy |
| Outer Diameter | See variant options |
| Hub / Flange | Flanged step design (belt retention) |
| Compatible Belt | GT2 / 2GT, 2mm pitch, 6–7mm width |
| Quantity | 1 piece per order |
The tooth count determines your drive ratio. Divide the driven pulley teeth by the driving pulley teeth to get the ratio. For 1:1 motion (e.g., CoreXY 3D printers), use identical tooth counts on both ends. For speed reduction or torque multiplication in CNC applications, use a larger driven pulley. Common choices for 3D printers are 20T (not in this range) to 40T; this listing covers 28T–58T for larger-format or higher-torque setups.
Most NEMA 17 stepper motors have a 5mm shaft diameter — select the 5mm bore. NEMA 23 motors typically use an 8mm or 6.35mm (1/4") shaft. Servo motors and DC motors vary widely; measure your shaft with calipers before ordering. If your shaft has a flat (D-cut), a keyway variant (e.g., 8mm – K 3mm) provides a more secure fit than a plain round bore with a set screw alone.
A plain through-hole bore relies on one or two set screws to grip the shaft. A keyway bore has a rectangular slot machined into the bore that accepts a matching key inserted into a keyway on the shaft. The key transmits torque mechanically, preventing rotational slippage under high load or reversing motion — important for CNC routers and servo-driven axes where set screws alone may loosen over time.
These pulleys have a 7mm belt-contact width and flanged steps. They are designed for 6mm or 7mm wide GT2 belts. A 6mm belt will run within the flanges without issue. Do not use belts wider than 7mm, as they will contact the flanges and cause premature wear.
Aluminum alloy pulleys are suitable for the belt tension and torque loads typical of desktop and mid-size CNC routers using NEMA 17 or NEMA 23 stepper motors. For very heavy-duty industrial CNC applications with high belt tension, steel pulleys may be more appropriate. For 3D printers, laser cutters, and light-to-medium CNC routers, aluminum alloy provides an excellent balance of weight and rigidity.
Aluminum alloy naturally forms a thin oxide layer that provides moderate corrosion resistance in typical indoor workshop environments. No lubrication is required or recommended on the pulley teeth — GT2 timing belts are designed to run dry. Avoid exposing the pulleys to prolonged moisture, cutting fluids, or harsh chemicals that could degrade the aluminum surface over time.
Yes, but you will need to recalibrate your printer's steps-per-mm setting. Changing from a 20T to a 28T pulley (the smallest in this range) changes the linear distance per motor step. Recalculate using the formula: steps/mm = (motor steps × microstepping) ÷ (teeth × belt pitch). Update your firmware accordingly after swapping pulleys.
