STS S3M 15-60T Timing Belt Pulley Pitch 3mm AF-type CNC Drive Pulleys Width 11mm

The number of teeth determines the pulley's pitch diameter and your drive ratio. Divide the desired output speed by the input speed to get your ratio, then select tooth counts accordingly. For example, a 20 T driver paired with a 40 T driven pulley gives a 2:1 reduction. Smaller tooth counts (15–20 T) suit compact, high-speed drives; larger counts (40–60 T) are used for torque multiplication or larger belt wrap angles.

Measure your motor or spindle shaft diameter with a caliper and select the matching bore. Common stepper motor shafts are 5 mm or 6.35 mm (1/4 in); servo motors often use 6 mm, 8 mm, or 10 mm. If your shaft is imperial (e.g., 1/4 in = 6.35 mm), select the 6.35 mm bore option. The AF-type hub includes a set-screw for secure locking once installed.

Yes. These pulleys are machined to the S3M tooth profile standard with a 3 mm pitch, making them directly compatible with any S3M open-end or closed-loop timing belt of 11 mm width. They are not compatible with other pitch standards such as GT2, HTD 3M, or T5 without verification of tooth profile geometry.

Aluminum alloy pulleys are well-suited for light-to-medium duty CNC, 3D printing, robotics, and automation applications. For the torque levels typical of NEMA 17 and NEMA 23 stepper motors or small servo motors, aluminum provides sufficient strength while keeping rotational inertia low. For heavy industrial loads or continuous high-torque applications, consult your system's torque requirements against the pulley's rated capacity.

The anodized aluminum surface provides good resistance to oxidation and mild chemical exposure typical of workshop environments. Anodizing creates a hard oxide layer that protects the base aluminum from corrosion. For wet or highly corrosive environments, additional protective measures may be advisable.

Yes. You can use any two pulleys from this series as a matched driver/driven pair, provided both are S3M profile and the belt width is 11 mm. Simply select the tooth counts that give your desired drive ratio. Using the same series ensures consistent tooth geometry and belt engagement on both sides of the drive.

AF-type (also called plain bore or through-bore with set-screw) means the bore is machined straight through the hub and secured to the shaft via one or more set-screws. This is the most common type for DIY and light industrial use. Other hub types include taper-lock (for quick removal under load) and keyway bores (for higher torque transmission). For most CNC and robotics applications, AF-type is sufficient and the easiest to install.