5M BF-Type Timing Belt Pulley 24-28T Synchronous Wheel For 15mm/20mm Width Belt

The tooth count determines the pulley's pitch diameter and, combined with your belt length and the driven pulley's tooth count, sets your drive ratio. A 24T pulley has a slightly smaller pitch diameter than a 25T pulley of the same pitch. If you are replacing an existing pulley, match the original tooth count exactly. If you are designing a new drive, calculate the required ratio (motor RPM ÷ desired output RPM) and select tooth counts accordingly. For most desktop CNC and 3D printer applications, 24T and 25T are interchangeable in 1:1 drive configurations.

Measure your motor or drive shaft diameter with calipers before ordering. Available round bores range from 6 mm to 20 mm, including 6.35 mm (1/4 in) and 12.7 mm (1/2 in) for imperial shafts. If your shaft has a keyway, select the matching keyed-bore variant (e.g., 8 mm with 3×1.4 mm keyway). A bore that is too large cannot be used safely; a bore that is too small requires machining. When in doubt, choose the bore that matches your shaft exactly.

For light-duty or low-torque applications (small 3D printer extruder drives, for example), a plain round bore secured with a set screw is typically sufficient. For higher-torque applications — such as CNC axis drives, conveyor systems, or servo motors — a keyed bore provides positive torque transmission and prevents the pulley from rotating on the shaft under load. If your shaft already has a machined keyway, always use the matching keyed-bore pulley variant.

Yes. The 5M designation refers to the HTD (High Torque Drive) 5M profile, which has a 5 mm pitch and a rounded tooth form. These pulleys are designed to mate with standard HTD 5M synchronous belts. Ensure your belt width matches the variant you select (15 mm or 20 mm). Do not use these pulleys with T5 or GT2 belts, as those have different tooth profiles and pitches.

Measure the width of your existing belt across its flat face. A 15 mm belt is approximately 0.59 inches wide; a 20 mm belt is approximately 0.79 inches wide. The pulley's flange spacing is matched to the belt width, so using a 20 mm belt on a 15 mm pulley (or vice versa) will result in poor tracking and accelerated belt wear. If you are designing a new system, 20 mm wide belts generally offer higher load capacity for the same pitch.

These pulleys are machined from aluminum alloy, which offers a favorable strength-to-weight ratio and natural corrosion resistance through the formation of an oxide layer. They are suitable for indoor workshop, laboratory, and light industrial environments. For outdoor or high-humidity environments, consider applying a light coating of machine oil to the bore and flanges. Aluminum pulleys are not recommended for direct contact with strong acids or alkalis.

Yes, provided the bore diameter matches your motor shaft and the belt pitch and width are correct. These pulleys are mechanically compatible with any motor type — stepper, servo, or DC — as long as the shaft diameter falls within the available bore range (6–20 mm). For servo motors with higher peak torques, prefer keyed-bore variants to prevent shaft slippage during rapid acceleration and deceleration cycles.