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When a slipping or misaligned drive pulley causes positioning errors in your CNC router, 3D printer, or automated conveyor, every lost step costs time and accuracy. Engineers, makers, and machine builders who demand repeatable motion need a synchronous wheel that holds its pitch under load — and that is exactly what these 3M timing belt pulleys are designed to deliver.
Each pulley is machined from aluminum alloy and features a 3M tooth profile (3 mm pitch). The range covers 20 to 38 teeth across two flange styles — BF-type (double-flanged) and K-type (single-flanged) — with bore diameters from 4 mm to 19 mm (approximately 0.16 in to 0.75 in) and keyway slot widths of 11 mm or 16 mm to suit standard set-screw or key-shaft assemblies.
Typical applications include 3M timing belt drive systems for desktop CNC machines and laser cutters, stepper-motor shaft couplings in 3D printer X/Y axes, and light-duty conveyor or indexing table synchronous drives where low backlash and consistent tooth engagement are critical.
| Belt Pitch | 3M (3 mm) |
|---|---|
| Tooth Profile | 3M synchronous (trapezoidal) |
| Number of Teeth | 20T / 22T / 24T / 25T / 28T / 30T / 32T / 35T / 36T / 38T |
| Flange Type | BF-type (double flange) / K-type (single flange) |
| Bore Diameter | 4 mm – 19 mm (see variant options) |
| Keyway Slot Width | 11 mm or 16 mm (see variant options) |
| Material | Aluminum alloy |
| Outer Diameter | See variant options |
| Hub Width | See variant options |
| Surface Finish | Natural anodized / machined |
| Compatible Belt | Standard 3M open-end or closed-loop timing belt |
| Quantity | 1 piece per order |
BF-type pulleys have flanges on both sides of the tooth face, which keeps the timing belt tracking centrally and prevents it from walking off under lateral forces — ideal for horizontal or multi-axis drives. K-type pulleys have a flange on one side only, which is useful when space constraints prevent a double-flanged pulley from fitting, or when the mating pulley already provides the opposing flange. If you are unsure, BF-type is the safer default for most desktop CNC and 3D printer applications.
Drive ratio equals the tooth count of the driven pulley divided by the tooth count of the driving pulley. For example, pairing a 20T driver with a 40T driven pulley gives a 2:1 reduction. Choose your tooth counts based on the speed and torque requirements of your axis. Smaller tooth counts produce higher belt wrap angles on small-diameter shafts, which can reduce tooth-skip risk at high torque. Larger tooth counts spread load across more teeth and suit higher-speed, lower-torque applications.
Measure your motor shaft diameter with calipers before ordering. Common stepper motor shaft sizes are 5 mm, 6.35 mm (1/4 in), 8 mm, and 10 mm. NEMA 17 motors typically use a 5 mm shaft; NEMA 23 motors commonly use 6.35 mm or 8 mm. Select the bore that matches your shaft exactly — a bore that is too large will require shimming and will introduce runout. If your shaft has a flat (D-cut), confirm the keyway slot width matches the flat dimension.
The keyway slot width refers to the width of the machined slot cut into the bore wall. An 11 mm slot suits narrower set-screw or key assemblies, while a 16 mm slot accommodates wider keys for higher-torque applications. Match the slot width to the key or flat on your shaft. If your shaft has no key, either slot width works — the set screw bears against the shaft directly. Check your shaft specification sheet or measure the flat width if present.
These pulleys are designed to the standard 3M tooth profile (3 mm pitch, trapezoidal tooth form) and will mesh correctly with any 3M-pitch timing belt that conforms to that standard, regardless of brand. Verify that your belt is labeled 3M or 3 mm pitch — do not confuse it with GT2 (2 mm pitch) or HTD 3M (a different tooth profile). If you are replacing an existing belt-and-pulley system, match the pitch of the existing belt.
Aluminum alloy pulleys offer a favorable strength-to-weight ratio for most light-to-medium duty synchronous drive applications, including CNC routers, 3D printers, laser cutters, and small conveyor systems. They are significantly lighter than steel, which reduces rotational inertia and improves acceleration response on servo and stepper axes. For heavy industrial loads exceeding the rated torque of the belt itself, steel pulleys may be warranted — but for the applications these pulleys are sized for, aluminum alloy is the standard material of choice.
Yes — this listing covers the pulley only. You will need to source a compatible 3M pitch timing belt separately. When selecting a belt, specify the pitch (3M), the belt width (match to your pulley tooth face width), and the length or number of teeth for closed-loop belts. Open-end belts can be cut to length. Ensure the belt width does not exceed the pulley tooth face width to avoid edge loading.
