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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 motion control need a pulley that fits their shaft precisely — not one that requires shimming or loctite to stay put. These GT2 2GT timing belt pulleys are designed for builders who won't compromise on dimensional accuracy.
Each pulley is machined from aluminum alloy with a hard-anodized finish, featuring a 2mm GT2 tooth profile and an 11mm belt-contact width. Tooth counts range from 70T to 120T (70, 72, 74, 75, 76, 78, 80, 90, 100, 110, 120 teeth), and through-hole bore diameters span 5mm to 25mm (approximately 0.20" to 0.98"). Keyway variants are available for bore sizes from 8mm upward, with keyway widths of 3mm, 4mm, 5mm, or 6mm depending on the bore selected. A set-screw step hub is included for secure shaft locking.
Typical use cases include large-format CNC router axis drives where high tooth count reduces belt wrap angle stress, direct-drive extruder systems on FDM 3D printers requiring precise filament feed ratios, and rotary axis or robotic arm joints where keyway engagement eliminates shaft slip under torque loads.
| Tooth Profile | GT2 / 2GT (2mm pitch) |
|---|---|
| Tooth Count Options | 70, 72, 74, 75, 76, 78, 80, 90, 100, 110, 120 teeth |
| Belt Width (tooth face) | 11mm (0.43") |
| Compatible Belt Width | 6mm or 10mm GT2 belts |
| Bore Diameter Range | 5mm – 25mm (0.20" – 0.98") |
| Keyway Options | 3mm, 4mm, 5mm, 6mm (bore-dependent; see variant options) |
| Material | Aluminum alloy |
| Hub Style | Stepped hub with set screw |
| Outer Diameter | See variant options |
| Quantity per Order | 1 piece |
The tooth count determines the pitch diameter and, combined with your motor pulley tooth count, sets the drive ratio. Higher tooth counts (e.g., 80T–120T) are typically used on the driven axis of a CNC router to reduce belt tension and increase torque multiplication. Lower tooth counts on the motor side paired with higher counts on the driven side create a speed-reduction / torque-increase ratio. Calculate your required ratio first, then select the tooth count that fits your available shaft and frame geometry.
NEMA 17 stepper motors typically have a 5mm output shaft, so the 5mm bore variant is the standard choice. NEMA 23 motors commonly use an 8mm or 1/4" (6.35mm) shaft — select the 8mm or 6.35mm bore accordingly. Always measure your actual shaft diameter with calipers before ordering, as some motors deviate from nominal sizing.
Keyway variants are recommended when the pulley must transmit significant torque without slipping, such as on a driven axis under heavy cutting loads or in a robotic joint subject to reversing torque. A keyway provides a positive mechanical interlock between the shaft and pulley, whereas a set screw alone can loosen over time under vibration. For light-duty 3D printer extruder or idler applications, a plain bore with set screw is typically sufficient.
Yes. The GT2 2mm tooth profile is identical whether the belt is open-loop (sold by the meter) or a closed-loop fixed-length belt. Ensure the belt width (6mm or 10mm) is compatible with the 11mm tooth face width of these pulleys — both widths run correctly on an 11mm-wide pulley with proper belt alignment guides or flanges.
Measure your shaft diameter with a micrometer or digital calipers to confirm it matches the selected bore size. For plain-bore variants, the set screw provides clamping force — ensure the shaft has a flat ground onto it for the set screw to seat against, which prevents the pulley from rotating on the shaft. For keyway variants, the key must match both the shaft keyway and the pulley keyway dimensions exactly.
6.35mm is the metric equivalent of exactly 1/4 inch (25.4mm ÷ 4 = 6.35mm). These are the same bore size — the 6.35mm variant is designed to fit 1/4" shafts commonly found on US-market stepper motors, servo motors, and small DC motors. If your motor shaft is labeled as 1/4", select the 6.35mm bore.
These large-tooth-count pulleys (70T–120T) are generally used on driven axes rather than direct-drive extruder gears, which typically use much smaller tooth counts (16T–20T). However, they are well-suited for the X/Y/Z axis belt drives on Cartesian and CoreXY printers, or as the driven pulley in a geared extruder reduction stage where a high gear ratio is needed.
