0.5 Mod 20-72 Teeth Rigid Aluminum Spur Gear Pinion Gear Motor Gear Bore 4-18mm

Divide the driven gear tooth count by the driver gear tooth count to get your ratio. For example, pairing a 20T pinion with a 40T gear gives a 2:1 reduction. Select the tooth counts that achieve your target ratio while keeping the center distance within your mechanical envelope. Center distance = (T1 + T2) × module / 2.

Measure your motor shaft diameter with calipers before ordering. Common sizes in this listing include 4, 5, 6, 6.35 (1/4 in), 8, 10, 12, 14, 15, 16, 17, and 18 mm. For K-Type gears, a slight clearance fit is acceptable since the set screw provides retention. For B-Type gears, a transition or light interference fit is recommended for secure mounting.

K-Type gears feature a hub with a set-screw hole, allowing you to lock the gear onto a shaft without adhesive or press-fitting tools — ideal for prototyping and applications where the gear may need to be repositioned. B-Type gears have a plain through-bore and rely on a press fit, adhesive, or an external retaining ring for shaft retention, which can provide a cleaner profile in space-constrained assemblies.

Aluminum alloy spur gears at 0.5 module are well-suited for light-to-medium duty applications such as robotics joints, 3D printer drives, and small automation mechanisms. For heavy-load or high-impact applications, consider a steel gear of the same module. Actual load capacity depends on tooth count, face width, operating speed, and lubrication — contact us to confirm suitability for your specific torque requirements.

Aluminum alloy forms a natural oxide layer that provides moderate corrosion resistance in typical indoor environments. For outdoor or high-humidity applications, a light coating of dry lubricant or grease on the tooth flanks is recommended to reduce wear and extend service life. Avoid prolonged exposure to salt spray or strong acids without additional surface protection.

Yes. Any gear with a 0.5 module and 20° pressure angle will mesh correctly regardless of material, as long as the tooth profile is standard involute. When pairing aluminum with steel, the aluminum gear will typically wear faster — this is often intentional in designs where the aluminum gear acts as a sacrificial element to protect a more expensive steel component.

For a standard spur gear: Outer Diameter (mm) = (Tooth Count + 2) × Module. For this 0.5 module series: a 20T gear has OD ≈ 11 mm, a 40T gear has OD ≈ 21 mm, a 60T gear has OD ≈ 31 mm, and a 72T gear has OD ≈ 37 mm. Use this formula to verify the gear fits within your housing or frame cutout before ordering.