HTD 8M Timing Belt Pulley for 15-40mm Wide, Bore 8-30mm, 30-40T, CNC 3D Printer

Tooth count determines your drive ratio and linear speed per motor revolution. A lower tooth count (e.g., 30T) gives a smaller pulley diameter and higher belt speed per RPM, while a higher count (e.g., 40T) gives a larger diameter and more torque multiplication when paired with a smaller driven pulley. Calculate your required linear speed and torque, then select the tooth count that achieves your target ratio with your motor's RPM range.

Match the bore diameter to your motor or gearbox output shaft. Common NEMA 17 stepper shafts are 5 mm; NEMA 23 shafts are typically 6.35 mm (0.25 in) or 8 mm; servo motors often use 8–14 mm shafts. If your shaft is imperial (e.g., 0.5 in = 12.7 mm), select the 12.7 mm bore option. The set screw secures the pulley once installed.

The "Applicable Belt Width" listed in each variant option (e.g., "12mm bore & 20mm belt") indicates the maximum belt width the pulley flanges are designed to guide. Always select a pulley whose belt-width rating matches or slightly exceeds your belt width. Using a narrower pulley with a wider belt will cause the belt to ride over the flanges and derail.

The HTD 8M profile is a heavy-duty timing belt standard rated for significantly higher torque than the smaller 3M or 5M profiles. The aluminum alloy construction provides adequate strength for most CNC router, laser cutter, and industrial automation drives. For very high-torque applications (e.g., large-format CNC with heavy gantries), verify that the belt's rated load capacity is the limiting factor, not the pulley.

The anodized aluminum finish provides a layer of corrosion resistance suitable for indoor workshop and light industrial environments. For prolonged outdoor exposure or contact with cutting fluids, periodic inspection is recommended. The anodized layer is harder than bare aluminum and resists light abrasion as well.

Variants listed with a key dimension in parentheses — such as "20mm(6x2.8mm)" — include a keyway machined into the bore. The numbers indicate the key width × key depth (e.g., 6 mm wide × 2.8 mm deep). Keyed bores provide positive rotational locking without relying solely on the set screw, making them preferable for high-torque or reversing-load applications. Standard bore variants use a set screw only.

Yes. The HTD 8M tooth profile is standardized, so these pulleys are compatible with both open-end (cut-to-length) and closed-loop (endless) HTD 8M timing belts of the matching width. Ensure the belt pitch is 8 mm and the tooth profile is HTD (rounded), not trapezoidal (XL, L, H, etc.).