HTD-5M 46T-75T Timing Belt Pulleys Pitch 5mm BF-type Bore 5mm-20mm Width 21mm

The tooth count determines your drive ratio. Divide the driven pulley's tooth count by the driving pulley's tooth count to get the ratio. For example, pairing a 20T motor pulley with a 60T axis pulley gives a 3:1 reduction. Choose a larger tooth count for more torque and slower speed; a smaller count for higher speed and less torque. Also verify that the resulting pulley outer diameter fits within your frame clearance.

Match the bore to your shaft diameter exactly. Common stepper motor shafts are 5 mm or 6.35 mm (1/4 in); NEMA 23 steppers typically use 6.35 mm or 8 mm; servo motors vary from 8 mm to 25 mm+. Measure your shaft with calipers before ordering. The BF-type bore includes a set-screw flat, so the shaft must have a matching flat or you should file one to prevent rotation.

Yes — these pulleys are designed for standard HTD 5M belts (5 mm pitch, rounded tooth profile). Ensure your belt width is compatible with the 21 mm pulley width; belts of 15 mm or 20 mm width are commonly used with this pulley size. Do not use with MXL, T5, GT2, or other non-HTD 5M profiles, as tooth geometry differs and will cause skipping or accelerated wear.

The BF-type bore uses a set screw bearing against a flat on the shaft, which provides reliable clamping for typical CNC and robotics loads. For very high-torque applications (e.g., heavy gantry axes or industrial conveyors), consider using thread-locking compound on the set screw and verifying torque limits against your motor's rated output. A keyway-style pulley may be more appropriate for sustained high-torque industrial duty cycles.

The anodized aluminum finish provides good resistance to oxidation, light moisture, and common workshop lubricants. It is suitable for indoor CNC, 3D printing, and robotics environments. Avoid prolonged exposure to salt spray, strong acids, or alkaline cutting fluids, which can degrade the anodized layer over time.

Yes. The BF-type bore design works on any shaft of the matching diameter, whether it is a motor output shaft, a lead screw coupling, or a driven axis shaft. Just ensure the bore size matches each shaft and that both pulleys are aligned in the same plane to prevent belt tracking issues and premature wear.

HTD (High Torque Drive) and GT2/GT3 are different tooth profiles and are not interchangeable. HTD has a semicircular tooth root designed for high-torque power transmission; GT2/GT3 uses a modified curvilinear profile optimized for low-backlash positioning. Mixing pulleys and belts of different profiles will cause poor meshing, skipping, and rapid wear. Always match pulley and belt profiles exactly.