8M Timing Belt Drive Pulley AF-type 50T/60T Bore 14mm-40mm Slot 16/21/27/32mm

The tooth count determines the pitch diameter and therefore the speed ratio between the driving and driven pulleys. A 50T pulley has a pitch diameter of approximately 127.3 mm, while a 60T pulley is approximately 152.8 mm. If you are replacing an existing pulley, match the original tooth count. If designing a new drive, choose 50T for a more compact assembly or 60T for smoother, lower-stress tooth engagement at higher torques.

AF-type pulleys use a plain (smooth) bore retained by one or two set screws tightened against the shaft. They are easy to install and reposition but can slip under heavy reversing loads. AF-type Keyway pulleys include a milled keyway slot that accepts a standard key, creating a positive mechanical lock between the pulley and shaft. Choose AF-type Keyway for servo drives, reversing axes, or any application where slip would cause positioning errors or damage.

The slot width should equal or closely match the width of your 8M timing belt. Common 8M belt widths are 16 mm, 21 mm, 25 mm, 30 mm, and 32 mm. Select the slot width option (16 mm, 21 mm, 27 mm, or 32 mm) that matches your belt width. Using a pulley narrower than the belt will cause the belt to overhang and wear unevenly; using one wider than the belt is generally acceptable but may require flanges to keep the belt tracking.

Measure your motor or gearbox output shaft diameter with a caliper. The bore you select should match the shaft diameter exactly — a loose bore will cause vibration and accelerated wear even with a set screw. For AF-type Keyway variants, also confirm that the keyway dimensions listed (e.g., 6×2.8 mm for a 19 mm bore) match the key already cut on your shaft, or plan to cut a matching key.

Yes. The 8M curvilinear tooth profile is designed for high-torque, moderate-to-high-speed synchronous drives. It is widely used in CNC routers, laser cutters, pick-and-place machines, and collaborative robot joints. For best results, ensure the belt tension is set correctly per the belt manufacturer's specification, the pulley bore is a close fit to the shaft, and — for reversing axes — use the AF-type Keyway variant to eliminate rotational play.

Keyway dimensions follow standard DIN 6885 / ISO 773 key-shaft fits and scale with bore size. As a guide: bores of 14–17 mm use a 5×2.3 mm keyway; 18–22 mm bores use 6×2.8 mm; 24–30 mm bores use 8×3.3 mm; 35–40 mm bores use 10×3.3 mm; and the 40 mm bore in the 32 mm slot variant uses 12×3.3 mm. The exact keyway for your chosen variant is shown in the Bore & Slot width option name (e.g., "19/6×2.8 mm & 21 mm" means 19 mm bore, 6×2.8 mm keyway, 21 mm slot).

In most cases, yes — provided the replacement pulley matches the original in pitch (8M), tooth count, bore diameter, keyway dimensions (if applicable), and slot width. Measure the original pulley carefully before ordering. If the original used a different hub style (e.g., taper-lock or QD bushing), these AF-type pulleys will not be a direct drop-in and may require a shaft modification or adapter.