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When a slipping or mismatched pulley causes timing errors in your CNC router, 3D printer, conveyor, or servo-driven machine, the entire system loses accuracy. Engineers, machine builders, and serious DIY makers who need a reliable synchronous drive component will find this HTD-8M timing belt pulley a direct, no-compromise solution.
Each pulley is machined from solid aluminum alloy (6061-grade equivalent), featuring an HTD-8M tooth profile with an 8mm pitch and a fixed belt width of 42mm (approximately 1.65 inches). Tooth counts range from 20T to 40T, with bore diameters from 12mm to 38mm (approximately 0.47 to 1.50 inches). Variants are available without a keyway (plain bore) or with standard keyways ranging from 4×1.8mm up to 10×4mm, matched to the bore size.
Typical applications include CNC axis drives requiring precise 8M synchronous belt engagement, industrial conveyor timing systems where consistent tooth pitch prevents belt skip, and servo motor coupling in robotics or automation rigs where a keyed bore ensures zero-slip torque transmission.
8mm pitch curvilinear tooth form engineered for smooth, low-noise meshing with standard HTD-8M belts — reduces stress concentration versus trapezoidal profiles.
Twelve tooth count options (20T, 22T, 24T, 25T, 26T, 28T, 30T, 32T, 34T, 36T, 38T, 40T) let you dial in the exact gear ratio your drive system requires.
Fourteen bore options from 12mm to 38mm cover a wide range of motor and shaft diameters, eliminating the need for custom machining in most applications.
Choose NO keyway for press-fit or set-screw mounting, or select a matched keyway (4×1.8mm, 5×2.3mm, 6×2.8mm, 8×3.3mm, or 10×4mm) for positive torque transmission without slip.
The 42mm (1.65 in) belt seat width provides a stable, wide contact surface that distributes load evenly and reduces edge wear on the belt.
Lightweight yet rigid aluminum body keeps rotational inertia low — ideal for high-acceleration servo and stepper motor applications where response time matters.
| Belt Profile | HTD-8M (curvilinear) |
|---|---|
| Pitch | 8mm |
| Belt Width | 42mm (1.65 in) |
| Number of Teeth | 20T, 22T, 24T, 25T, 26T, 28T, 30T, 32T, 34T, 36T, 38T, 40T |
| Bore Diameter | 12, 14, 15, 16, 17, 18, 19, 20, 22, 24, 25, 28, 30, 38mm |
| Keyway Options | NO (plain bore), 4×1.8mm, 5×2.3mm, 6×2.8mm, 8×3.3mm, 10×4mm |
| Material | Aluminum alloy |
| Pitch Diameter Range | Approx. 50.9mm (20T) – 101.9mm (40T) |
| Outside Diameter Range | See variant options |
| Hub Style | Without step (straight hub) |
| Quantity per Order | 1 piece |
| Weight | See variant options |
| Surface Finish | See variant options |
The tooth count determines the pitch diameter and, combined with your driven pulley's tooth count, sets the drive ratio. Divide the driven pulley teeth by the driver pulley teeth to get the ratio. For example, a 20T driver paired with a 40T driven pulley gives a 2:1 reduction. Use a smaller tooth count for higher speed output and a larger count for more torque.
Measure your motor or drive shaft diameter with calipers. Select the bore that matches exactly — for example, a 19mm shaft requires the 19mm bore option. If your shaft diameter falls between listed sizes, contact us to confirm before ordering. Do not select an oversized bore and attempt to shim it, as this will cause runout and belt skip.
A keyway is required when transmitting significant torque or when the shaft must not rotate relative to the pulley under load. The keyway dimensions are matched to the bore per standard DIN 6885 guidelines: 12mm bore → 4×1.8mm; 14–15mm bore → 5×2.3mm; 16–17mm bore → 5×2.3mm; 18–22mm bore → 6×2.8mm; 24–28mm bore → 8×3.3mm; 38mm bore → 10×4mm. If your shaft has no keyway slot, choose the NO keyway option and secure with a set screw.
Yes — this pulley is designed to the standard HTD-8M tooth profile and will mesh correctly with any HTD-8M synchronous belt that is 42mm wide. Ensure your belt width matches the 42mm seat. Using a narrower belt on this pulley is not recommended as it will not track properly and may cause premature wear.
Aluminum alloy pulleys are well-suited for most servo, stepper, and light industrial drive applications. The 8M profile distributes load across multiple teeth simultaneously, reducing per-tooth stress. For very high torque applications with shock loads, consider whether a steel pulley would be more appropriate. Contact us with your torque and RPM requirements if unsure.
Aluminum naturally forms a thin oxide layer that provides good corrosion resistance in most indoor and light-duty environments. For humid, wet, or chemically aggressive environments, additional anodizing or coating may be advisable. Contact us if you require a specific finish such as hard anodize.
Yes. HTD-8M pulleys are commonly used on larger-format CNC routers, laser cutters, and industrial 3D printers where higher torque and wider belts are needed. Confirm that your machine's belt is HTD-8M and that the belt width is 42mm before selecting your variant.
Pitch diameter (PD) = (Number of Teeth × Pitch) ÷ π. For this 8mm pitch pulley: 20T ≈ 50.9mm, 22T ≈ 56.0mm, 24T ≈ 61.1mm, 25T ≈ 63.7mm, 26T ≈ 66.2mm, 28T ≈ 71.3mm, 30T ≈ 76.4mm, 32T ≈ 81.5mm, 34T ≈ 86.6mm, 36T ≈ 91.7mm, 38T ≈ 96.8mm, 40T ≈ 101.9mm.
