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When your motion system demands repeatable, slip-free power transfer, a mismatched or worn pulley becomes the weakest link in the chain. Engineers, makers, and CNC builders who need a reliable HTD-3M timing belt pulley with a keyed bore will find this AF-type wheel a direct, drop-in solution across a wide range of shaft sizes and tooth counts.
Each HTD-3M timing belt pulley in this listing features a 3mm pitch HTD tooth profile machined to accept standard 3M timing belts. The wheel width is 11mm, and the bore diameter ranges from 8mm (~0.31 in) to 25mm (~0.98 in) depending on the variant selected. Tooth counts span 17T through 80T, giving pitch circle diameters from approximately 16.2mm (~0.64 in) up to 76.4mm (~3.01 in). Each pulley ships with a pre-cut keyway matched to the bore size — keyway dimensions range from 3×1.4mm (for 8–10mm bores) up to 8×3.3mm (for 25mm bores).
Typical use cases include 3D printer X/Y axis drives requiring low-backlash HTD-3M pulley sets, desktop CNC router spindle-to-motor belt drives needing a keyed 3mm pitch pulley, and compact robotics joint actuators where a lightweight AF-type timing pulley with keyway keeps assembly weight minimal.
| Belt Pitch | 3mm (HTD-3M) |
|---|---|
| Tooth Profile | HTD (rounded) |
| Tooth Count Range | 17T – 80T (see variant options) |
| Wheel Width | 11mm |
| Bore Diameter | 8mm / 10mm / 12mm / 12.7mm / 14mm / 15mm / 16mm / 17mm / 18mm / 19mm / 20mm / 25mm (see variant options) |
| Keyway Dimensions | 3×1.4mm / 4×1.8mm / 5×2.3mm / 6×2.8mm / 8×3.3mm (matched to bore) |
| Pulley Type | AF-type (flanged, with keyway) |
| Material | See variant options |
| Pitch Circle Diameter | See variant options |
| Compatible Belt Width | ≤11mm |
| Quantity per Order | 1 piece |
The tooth count determines the pitch circle diameter and, combined with your motor pulley tooth count, sets the drive ratio. Divide the driven pulley teeth by the drive pulley teeth to get the reduction ratio. For example, a 3M40T driven by a 3M20T gives a 2:1 reduction. Use a smaller tooth count for higher speed output and a larger tooth count for more torque.
Match the bore diameter to your motor or drive shaft diameter. Common NEMA 17 stepper motors use 5mm shafts (not listed — check your motor spec), while NEMA 23 motors typically use 6.35mm (1/4 in) or 8mm shafts. Servo motors and DC gearmotors often use 8mm, 10mm, or 12mm shafts. Select the bore that matches your shaft, then confirm the keyway dimension aligns with your shaft's key slot.
Keyway dimensions are matched to the bore size per DIN 6885 standard conventions: 8–10mm bore uses a 3×1.4mm keyway; 12–12.7mm bore uses 4×1.8mm or 5×2.3mm; 14–17mm bore uses 5×2.3mm; 18–20mm bore uses 6×2.8mm; 25mm bore uses 8×3.3mm. The exact keyway for each variant is shown in the Keyway option selector above.
Yes. This pulley is designed for standard HTD-3M open or closed-loop timing belts with a 3mm pitch and a belt width of 11mm or less. It will not fit MXL, T2.5, T5, or GT2 belts, which use different tooth profiles. Always verify the belt pitch and profile before ordering.
The AF-type design uses a machined keyway slot that mates with a key inserted between the shaft and pulley bore, providing a positive mechanical lock. This is significantly more secure than set-screw-only retention for continuous or reversing loads. For very high torque applications, confirm the key material and fit tolerance match your shaft specification.
Corrosion resistance depends on the pulley material. If your application involves moisture, chemicals, or outdoor exposure, contact us to confirm the material of the specific variant you need before ordering. For harsh environments, consider adding a protective coating or selecting a stainless or anodized variant if available.
AF-type pulleys include side flanges that help keep the timing belt centered on the pulley face during operation, reducing the risk of belt walk-off in open-loop or lightly tensioned systems. Non-flanged pulleys rely on belt tension and frame alignment alone. For most CNC and robotics builds, AF-type is the recommended choice for reliable belt tracking.
