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When your motor transmission project demands consistent tooth engagement and reliable torque transfer, undersized or poorly machined gears become the weak link. Whether you're a robotics engineer, RC hobbyist, or mechanical DIYer, these 0.5 module spur gears are machined to deliver repeatable performance across a wide range of drive configurations.
Each gear is machined from 45# carbon steel, offering a solid balance of hardness and machinability. The 0.5 module (Mod 0.5) standard governs tooth profile geometry, with tooth counts ranging from 25T to 60T and bore sizes spanning 4 mm (0.157 in) to 15 mm (0.591 in). Tooth thickness varies by model — 3 mm or 5 mm — and select variants feature a keyway bore for positive shaft locking. Overall gear outer diameter ranges from approximately 13.5 mm (0.53 in) for 25T up to approximately 31 mm (1.22 in) for 60T.
Typical use cases include small DC motor gearboxes for robotics and automation, RC car and truck drivetrain reduction stages, and custom pinion gear assemblies for 3D printer extruder or CNC axis drives. The wide tooth-count selection makes it straightforward to dial in your target gear ratio for any 0.5 module spur gear motor transmission application.
Machined from 45# medium-carbon steel for a reliable combination of surface hardness and core toughness — suited for continuous-duty motor transmission loads.
Wide Tooth Count Range: 25T – 60TTwenty-six tooth-count options let you select the exact gear ratio needed for your drivetrain, from compact 25-tooth pinions to large 60-tooth driven gears.
Multiple Bore Sizes: 4 mm – 15 mmStandard round bores from 4 mm to 15 mm (including 6.35 mm / ¼ in) plus keyway variants (8/3×1.4, 10/3×1.4, 10/4×1.8, 12/4×1.8, 14/5×2.3, 15/5×2.3) cover most motor shaft standards.
Keyway Bore Options AvailableSelect 48T, 50T, and 60T variants are offered with keyway bores for positive shaft-to-gear locking — eliminating slip under high-torque or reversing loads.
Dual Tooth Thickness Options on Key Sizes30T and 40T gears are available in both 3 mm and 5 mm tooth thickness, allowing you to match face width to your load requirements and available axial space.
Standard Mod 0.5 Profile for Universal MeshingConforms to the international Module 0.5 tooth profile standard, ensuring correct mesh with any other Mod 0.5 spur gear, rack, or pinion in your assembly.
| Module | 0.5 (Mod 0.5) |
|---|---|
| Tooth Count Range | 25T – 60T (see variant options) |
| Material | 45# Carbon Steel |
| Bore Size Range | 4 mm – 15 mm (round); keyway bores available on select sizes |
| Tooth Thickness | 3 mm or 5 mm (see variant options) |
| Outer Diameter (approx.) | ~13.5 mm (25T) to ~31 mm (60T) |
| Pressure Angle | 20° (standard Mod 0.5) |
| Gear Type | Spur (straight tooth) |
| Keyway | Available on 48T, 50T, 60T variants |
| Quantity per Order | 1 piece |
| Weight | See variant options |
Divide the number of teeth on the driven gear by the number of teeth on the driving (pinion) gear to get your gear ratio. For example, a 50T driven gear meshed with a 25T pinion gives a 2:1 reduction. Select tooth counts that achieve your target ratio while fitting within your available center distance.
Measure your motor shaft diameter with calipers. Available round bores are 4, 5, 6, 6.35, 8, 10, 12, 14, and 15 mm. For a ¼-inch shaft, select the 6.35 mm bore. If you need a positive lock, choose a keyway bore variant (available on 48T, 50T, and 60T) and match the keyway dimensions to your shaft key.
Tooth thickness (face width) affects load capacity. The 5 mm face width distributes torque over a wider contact area, making it better suited for higher-load or higher-speed applications. The 3 mm option is more compact axially and works well in space-constrained assemblies with moderate loads.
45# carbon steel provides a tensile strength of approximately 600–700 MPa in the normalized condition, making these gears suitable for continuous-duty light-to-medium motor transmission applications such as robotics joints, RC drivetrains, and small automation axes. For very high shock loads, consider heat-treated or alloy steel gears.
45# carbon steel has moderate corrosion resistance. For outdoor or humid environments, apply a light machine oil or grease to the gear teeth and bore after installation. If corrosion resistance is a primary requirement, consider stainless steel or plastic gear alternatives.
Yes. These gears conform to the standard Module 0.5 tooth profile (20° pressure angle), so they mesh correctly with any other Mod 0.5 spur gear, pinion, or rack regardless of manufacturer, as long as the module and pressure angle match.
Center distance = (T1 + T2) × Module / 2, where T1 and T2 are the tooth counts of the two gears. For example, a 25T and 50T Mod 0.5 pair: (25 + 50) × 0.5 / 2 = 18.75 mm center distance.
