HTD-5M 42-120Teeth Timing Belt Pulley Pitch 5mm AF-type Drive Pulleys Width 16mm

The tooth count determines the pitch diameter and, combined with your motor pulley tooth count, sets your drive ratio. A larger driven pulley (more teeth) reduces output speed and increases torque; a smaller one does the opposite. For CNC and 3D printer axes, 20T driver + 40T driven is a common 2:1 ratio. Use the formula: Pitch Diameter = (Teeth × Pitch) ÷ π. Select the tooth count that achieves your target ratio and fits within your frame geometry.

Measure your shaft diameter with calipers and select the matching bore. Common stepper motor shaft sizes are 5mm, 6.35mm (1/4 in), and 8mm; servo motor output shafts are often 10–20mm. The AF-type set screw locks onto a flat or round shaft — for best grip, use a shaft with a D-flat or keyway aligned with the set screw. If your shaft size is not listed, contact us to confirm availability.

Yes. These pulleys are machined to the HTD-5M standard tooth profile (5mm pitch, curvilinear tooth form) and are compatible with any HTD-5M belt up to 16mm wide. They are not compatible with T5, GT2, or other pitch belts — always verify the belt profile before ordering.

Aluminum alloy pulleys are well-suited for light-to-medium duty applications such as CNC routers, 3D printers, laser cutters, and small automation systems. For very high torque or heavy industrial loads, steel pulleys are typically recommended. The anodized surface adds hardness and wear resistance to the tooth flanks, extending service life under normal operating conditions.

Anodizing creates an aluminum oxide layer that provides good resistance to moisture and mild chemical exposure, making these pulleys suitable for indoor environments with occasional humidity. For prolonged outdoor exposure or contact with aggressive chemicals, additional protective measures (such as a clear coat or periodic lubrication of the bore) are advisable.

These pulleys follow standard HTD-5M pitch and groove dimensions, so they are dimensionally interchangeable with other 5M-pitch pulleys of the same tooth count and groove width. Verify your existing pulley's tooth count, bore diameter, and belt width before ordering. If your machine uses a 15mm or 16mm wide HTD-5M belt, this pulley will fit without modification.

AF-type (also called "pilot bore" or "set-screw bore") means the bore is finished to a specific diameter and secured to the shaft with one or two radial set screws. This is the simplest and most common bore style for small-to-medium pulleys. It differs from taper-lock or keyway bores, which require a separate bushing or machined keyway. AF-type is ideal when you need quick installation or plan to reposition the pulley on the shaft.