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When a slipping or misaligned pulley causes your CNC router, 3D printer, or pick-and-place machine to lose steps, every job suffers. Engineers and makers who need repeatable, zero-backlash motion rely on a properly matched 3M timing belt drive pulley AF-Type to keep their synchronous drive systems running true. This listing covers the full AF-Type range so you can source the exact tooth count and bore in one place.
Each pulley is machined from aluminum alloy with a natural or anodized finish and features the AF-Type flange configuration — a flanged hub on one side that keeps the 3M pitch (3 mm / 0.118 in) timing belt tracking straight. Tooth counts span 35 T through 60 T, and bore sizes range from 5 mm (0.197 in) to 20 mm (0.787 in), with slot widths of 11 mm to accommodate standard set-screw clamping. Keyway-bore variants (e.g., 8 mm × 3 × 1.4 mm, 10 mm × 4 × 1.8 mm, 12 mm × 5 × 2.3 mm) are also available for keyed shaft applications.
Typical use cases include CNC router X/Y axis drives requiring a 3M timing belt pulley for stepper motor shafts, desktop laser engraver feed systems where a 35-tooth to 60-tooth synchronous pulley maintains consistent belt tension, and robotics joint actuators that need a compact AF-type flanged pulley for precise angular positioning.
The flanged hub on one side guides the timing belt laterally, preventing walk-off during high-speed or reversing motion without adding unnecessary width to the drive assembly.
Matches all standard 3M synchronous belts. The 3 mm tooth pitch delivers a balance of torque capacity and compact pulley diameter, making it a go-to choice for desktop CNC and robotics builds.
Ten tooth-count options let you dial in the exact gear ratio your drive system needs — from the smaller 35 T for higher speed to the larger 60 T for increased torque multiplication.
Round bores from 5 mm to 20 mm plus keyed bores (3×1.4 mm, 4×1.8 mm, 5×2.3 mm keyways) cover the most common stepper and servo motor shaft standards, including 1/4 in (6.35 mm) and 1/2 in (12.7 mm) imperial sizes.
Lightweight yet rigid aluminum alloy body keeps rotational inertia low — critical for responsive acceleration and deceleration in motion-control applications like CNC and pick-and-place systems.
The 11 mm slot width accommodates standard M3–M4 set screws, providing a firm grip on the motor shaft without requiring special tooling or adapters.
| Belt Pitch | 3 mm (3M) |
|---|---|
| Pulley Type | AF-Type (single flange) |
| Number of Teeth | 35 T, 36 T, 38 T, 40 T, 44 T, 45 T, 48 T, 50 T, 55 T, 60 T |
| Bore Size Range | 5 mm – 20 mm (round); keyed bores available |
| Slot Width | 11 mm |
| Keyway Options | 3×1.4 mm, 4×1.8 mm, 5×2.3 mm (see variant options) |
| Material | Aluminum alloy |
| Finish | See variant options |
| Compatible Belt Width | See variant options |
| Pitch Diameter (approx.) | See variant options |
| Hub Configuration | Single flange (AF-Type) |
| Application | CNC, 3D printer, laser engraver, robotics, automation |
The tooth count determines your pulley's pitch diameter and, combined with the tooth count on the mating pulley, sets your drive ratio. For a 1:1 ratio use identical tooth counts on both pulleys. For speed reduction, use a larger tooth count on the driven pulley; for speed increase, use a smaller count. Common CNC builds use 20 T driver / 40 T driven for 2:1 reduction, but this listing's 35–60 T range lets you fine-tune ratios for your specific axis requirements.
Match the bore to your motor shaft diameter. NEMA 17 steppers typically have a 5 mm shaft; NEMA 23 steppers commonly use 6.35 mm (1/4 in) or 8 mm shafts. If your shaft has a keyway, select the corresponding keyed bore variant (e.g., 8 mm × 3×1.4 mm). For plain shafts, a round bore with set-screw clamping is sufficient.
Yes — any synchronous belt with a 3 mm tooth pitch (3M profile) will mesh with these pulleys. Ensure the belt width does not exceed the pulley's usable belt-contact width. The AF-Type flange helps retain the belt on one side; for double-sided retention, pair with a matching flanged idler or use a belt guide.
Aluminum alloy pulleys are well-suited for the torque levels produced by NEMA 17 and NEMA 23 stepper motors in typical CNC and robotics applications. The limiting factor is usually belt tension rather than pulley strength. For very high-torque industrial drives, consider a keyed bore variant to distribute clamping load more evenly across the shaft.
Aluminum alloy naturally forms a thin oxide layer that provides moderate corrosion resistance. For environments with moisture, mild chemicals, or salt air, an anodized finish variant offers improved surface protection. Avoid prolonged exposure to strong acids or alkalis regardless of finish.
Yes. The pulleys are shaft-agnostic — they work with any motor whose shaft diameter matches the selected bore. Servo motors with 6 mm, 8 mm, or 10 mm shafts are common, and all of those bore sizes are available in this listing. Select the appropriate bore and keyway option to match your servo's shaft specification.
A round bore uses one or two set screws to clamp the pulley onto a smooth shaft. This is simple to install and reposition but can slip under sustained high torque. A keyed bore includes a rectangular slot (keyway) that mates with a matching key on the motor shaft, providing a positive mechanical lock that prevents rotational slipping — preferred for higher-torque or reversing-load applications.
