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When a slipping or mismatched pulley causes your motion system to lose steps, skip positions, or vibrate under load, the root cause is almost always a poorly toleranced synchronous wheel. Engineers, makers, and machine builders who rely on repeatable linear or rotary motion need an HTD3M timing pulley that holds its bore and tooth profile to spec across every cycle. This HTD3M timing pulley series is designed for exactly that demand.
Each pulley is machined from aluminum alloy (typically 6061-T6) and features the HTD 3M tooth profile — 3mm pitch, 15mm belt width — with teeth counts ranging from 15 to 38T and bore options from 4mm to 25mm (approximately 0.16" to 0.98"). Keyway variants are available for positive torque transmission without set-screw slippage. The outer diameter scales with tooth count, typically ranging from approximately 14mm to 36mm (0.55" to 1.42").
Typical use cases include 3D printer X/Y axis drives requiring low backlash HTD3M pulleys, CNC router spindle synchronization with 15mm wide belt pulleys, and desktop robotic arm joints where a compact aluminum timing pulley with keyway ensures zero-slip torque coupling.
3mm pitch curvilinear tooth geometry distributes belt load evenly, reducing tooth shear stress and extending belt life compared to trapezoidal profiles.
15 to 38 teeth and bore sizes from 4mm to 25mm (including 6.35mm / 1/4" and 12.7mm / 1/2" imperial sizes) cover the majority of motion-system shaft standards.
Select bore options include a precision-cut keyway (3mm, 4mm, 5mm, or 6mm key) for positive torque coupling — eliminating set-screw creep under reversing or high-cycle loads.
Machined from aluminum alloy for a low-inertia, corrosion-resistant pulley body. The anodized or natural finish resists oxidation in typical workshop and indoor automation environments.
The 16mm-wide tooth section (TC16 in SKU) accommodates standard 15mm HTD3M belts with lateral retention, keeping the belt tracked under dynamic loads.
Standard HTD3M tooth spacing ensures interchangeability with other HTD3M pulleys and belts from common motion-system suppliers — no custom belt required.
| Belt Profile | HTD 3M (3mm pitch, curvilinear) |
|---|---|
| Belt Width | 15mm (hub width 16mm) |
| Teeth Number | 15 – 38 T (see variant options) |
| Bore Diameter | 4 / 5 / 6 / 6.35 / 7 / 8 / 10 / 12 / 12.7 / 14 / 15 / 16 / 17 / 18 / 19 / 20mm (see variant options) |
| Keyway Options | 3mm / 4mm / 5mm / 6mm key (select bore variants) |
| Outer Diameter | See variant options (scales with tooth count) |
| Material | Aluminum alloy |
| Finish | See variant options |
| Pitch Diameter | See variant options |
| Set Screw | Contact us to confirm |
| Weight | See variant options |
The teeth count determines the pitch diameter and therefore the drive ratio. For a given belt length and center distance, a smaller pulley (fewer teeth) on the motor shaft paired with a larger pulley on the driven shaft creates a speed reduction and torque multiplication. Use a belt-drive calculator: enter your center distance, desired ratio, and 3mm pitch to find the ideal teeth combination. Common pairings for 3D printers are 20T motor / 20T idler for 1:1, or 16T / 32T for 2:1 reduction.
For applications with reversing loads, high cycle counts, or significant torque, a keyway bore provides positive mechanical engagement that a set screw alone cannot match. Set-screw bores are suitable for light-duty, unidirectional, or low-torque applications such as 3D printer extruder drives. If your system reverses direction frequently — such as a CNC axis — select a keyway variant to prevent the pulley from rotating on the shaft over time.
The HTD 3M tooth profile is an industry-standard geometry (3mm pitch, curvilinear tooth form). This pulley is compatible with any HTD3M timing belt of 15mm width from any manufacturer that conforms to the HTD standard. It is not compatible with GT2 or MXL belts, which use different tooth profiles despite similar pitch values.
Measure your motor or drive shaft diameter with a caliper. Common NEMA 17 stepper shafts are 5mm; NEMA 23 shafts are typically 6.35mm (1/4") or 8mm; servo motor shafts vary from 8mm to 20mm. Select the bore that matches your shaft diameter exactly — a loose fit will cause vibration and positional error. If your shaft has a flat or keyway, choose the corresponding keyway bore variant.
Aluminum alloy offers good natural corrosion resistance due to its self-forming oxide layer. For typical indoor automation, workshop, or 3D printing environments, no additional treatment is required. For humid or mildly corrosive environments, an anodized finish provides additional protection. These pulleys are not recommended for continuous immersion or highly corrosive chemical environments — contact us to confirm finish details for your specific conditions.
Yes, provided the teeth count, bore diameter, and belt width match your existing setup. The HTD3M tooth profile is standardized, so a 20T HTD3M pulley from this listing will mesh correctly with any 20T HTD3M belt. Verify the hub width (16mm here) fits within your frame clearance, and confirm the bore and any keyway dimensions match your shaft before ordering.
6.35mm is the metric equivalent of 1/4 inch, a common shaft size in North American and some European servo and stepper motors. The 6mm bore fits metric shafts. They are not interchangeable — a 6mm shaft in a 6.35mm bore will have approximately 0.35mm of radial play, causing vibration and positional error. Always match the bore to your exact shaft diameter.
