H-Type Timing Belt Idler Pulley Pitch 12.7mm CNC Toothed Tensioner Width 27mm

The tooth count determines the pulley's pitch diameter and affects the wrap angle of the belt around the idler. A higher tooth count gives a larger diameter, which can improve belt wrap and reduce bending stress on the belt. For most CNC and 3D printer tensioner applications, H12T–H16T are common choices. If you need a larger wrap angle or are working with a longer belt span, H18T or H20T may be more appropriate. Match the tooth count to your drive geometry and available mounting space.

Select the bore diameter that matches your shaft diameter exactly. Available bores are 10mm, 12mm, 15mm, 17mm, 20mm, 25mm, and 30mm. If your shaft is metric, choose the matching size. If you are using an imperial shaft, convert to the nearest metric equivalent and verify fit before final assembly. A bore that is too large will require a bushing or set-screw collar to secure properly.

Yes — this pulley is designed for standard H-series synchronous timing belts with a 12.7mm (0.500 in) pitch. The belt contact width is 27mm, so it is best paired with H-series belts up to 27mm wide (e.g., H075, H100 width designations). Confirm your belt's pitch and width before ordering to ensure full tooth engagement across the belt face.

A toothed idler engages the belt teeth directly, preventing the belt from riding up or skipping under load. This is especially important in high-torque or high-speed applications where a smooth idler could allow the belt to slip laterally or lose tooth engagement. For CNC routing and 3D printing where positional accuracy matters, a toothed idler tensioner provides more consistent tension and better belt tracking than a smooth alternative.

The pulley is CNC-machined from aluminum alloy, which offers a good balance of strength, low weight, and corrosion resistance for indoor mechanical applications. Aluminum is suitable for the load levels typical of CNC machines, 3D printers, and light automation equipment. For environments with exposure to moisture or chemicals, consider applying a light lubricant or protective coating to the bore and mounting surfaces.

This pulley is designed and listed as an idler/tensioner component. While the toothed profile is geometrically compatible with H-series belts, idler pulleys are typically not keyed or designed to transmit torque from a shaft. If you need a drive pulley (one that is keyed or set-screwed to a motor shaft to transmit torque), please look for a dedicated H-type drive pulley with a keyway or set-screw specification.

Each order includes 1 piece (1Pcs) as shown in the Amount variant option. If you need multiple pulleys for a multi-axis machine or a complete tensioner kit, simply increase the quantity in your cart or place multiple orders for different bore/tooth count combinations.