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When a slipping or mismatched pulley is costing you accuracy on your CNC router, 3D printer, or conveyor drive, the root cause is almost always a pulley that wasn't machined to spec. Engineers and makers who demand repeatable positioning need an HTD-5M timing belt pulley they can trust to mesh cleanly with standard 5M belts, run true under load, and accept a keyed shaft without play. This listing covers the full range of HTD-5M pulleys in 21mm belt width, available in both K-type (pilot-bore) and BF-type (finished bore with flange) configurations.
Each pulley is machined from aluminum alloy, featuring an HTD-5M tooth profile with a 5mm pitch and 21mm working width. Tooth counts range from 10T to 75T (approximately 0.39 in to 2.95 in pitch diameter range), with finished bore options from 8mm to 28mm (0.31 in to 1.10 in) and matching keyway slots sized 3×1.4mm, 4×1.8mm, 5×2.3mm, 6×2.8mm, or 8×3.3mm depending on bore size. The anodized surface resists corrosion and wear in light-duty industrial and workshop environments.
Typical applications include CNC axis drives requiring HTD-5M belt pulley replacement, 3D printer extruder and motion system upgrades, light conveyor and indexing table builds, and robotics joint actuators where a keyed timing pulley with 5mm pitch is specified. The BF-type flange variant is particularly suited to open-belt runs where lateral belt retention is needed without a separate guide.
| Belt Profile | HTD-5M |
|---|---|
| Pitch | 5mm (0.197 in) |
| Belt Width (Working) | 21mm (0.83 in) |
| Tooth Count Range | 10T – 75T |
| Bore Range | 8mm – 28mm (0.31 – 1.10 in) |
| Keyway Size | See variant options |
| Material | Aluminum alloy |
| Surface Treatment | Anodized |
| Hub Type | K-type (pilot bore) / BF-type (finished bore with flange) |
| Quantity per Order | 1 piece |
| Weight | See variant options |
The tooth count determines the pitch diameter of the pulley and, combined with the tooth count of the mating pulley, sets your drive ratio. Divide the driven pulley teeth by the driver pulley teeth to get the ratio. For CNC axes, common driver pulleys are 20T or 25T paired with a matching tooth count on the motor shaft. If you are replacing an existing pulley, match the tooth count exactly.
K-type pulleys have a pilot bore that can be bored out to a custom diameter in a lathe — useful when your shaft size is non-standard. BF-type pulleys come with a finished bore to the listed diameter, a set-screw or keyway for shaft locking, and integrated flanges on both sides of the belt groove to keep the belt tracking without a separate guide. For most direct-mount applications, BF-type is the ready-to-use choice.
Yes — these pulleys are machined to the HTD-5M standard (5mm pitch, curved tooth profile). They are compatible with any standard HTD-5M open or closed timing belt up to 21mm wide. Do not use with MXL, GT2, or other pitch profiles, as the tooth geometry is different and will cause premature wear or belt jump.
The keyway provides a positive mechanical connection between the pulley and shaft, transmitting torque through the key rather than relying solely on friction. For the torque levels typical of CNC routers, 3D printers, and light conveyor drives, a properly fitted key and set screw will not slip. Ensure the key is a snug fit in both the shaft keyway and the pulley keyway, and tighten the set screw to the manufacturer's specification for your shaft diameter.
Aluminum alloy with an anodized finish is well-suited for indoor workshop, CNC, 3D printing, and light industrial automation environments. The anodizing provides corrosion resistance against moisture and mild chemicals. These pulleys are not recommended for outdoor exposure to salt spray or highly corrosive chemical environments — in those cases, consider stainless steel alternatives.
Measure your motor or drive shaft diameter precisely with a caliper. Select the bore option that matches your shaft diameter. The keyway dimensions are automatically matched to the bore size per standard DIN 6885 key sizing: 8mm bore uses 3×1.4mm key, 10–12mm bore uses 3×1.4mm or 4×1.8mm, 14–17mm bore uses 5×2.3mm, 18–20mm bore uses 6×2.8mm, and 24–28mm bore uses 8×3.3mm. If your shaft already has a keyway cut, verify the key width matches before ordering.
Yes. HTD-5M pulleys are widely used in CoreXY, Cartesian, and delta 3D printer motion systems, particularly for extruder drives and Z-axis lead screw alternatives. Ensure your belt is also HTD-5M profile and that the belt width does not exceed 21mm. For typical NEMA 17 motor shafts (5mm diameter), you would need to select a bore option and have the pilot bore machined, or use a 5mm bore variant if listed.
