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When a mismatched or undersized gear causes slippage, noise, or premature failure in your motion-control build, the root cause is almost always a compromise on material or dimensional accuracy. Engineers, CNC builders, and automation integrators who need a reliable, drop-in Module 2 spur gear with a keyed bore will find this C45 steel pinion engineered to hold up under real load cycles without play or wobble.
Each gear is machined from C45 medium-carbon steel and finished with a black oxide coating that reduces surface friction and provides baseline corrosion resistance. The tooth count spans 12 to 30 teeth, and bore diameters range from 10 mm (0.39 in) to 32 mm (1.26 in) with matching keyways from 4 mm to 10 mm wide — allowing direct shaft coupling without set-screw slippage. Overall gear outer diameter scales proportionally with tooth count, typically from approximately 28 mm (1.10 in) for a 12T up to approximately 64 mm (2.52 in) for a 30T at Module 2 geometry.
Typical use cases include CNC router Z-axis and rack-and-pinion drives, conveyor and indexing table geartrains, robotic arm joint actuators, and light industrial automation where a keyed Module 2 pinion is the standard interface. Long-tail search terms this product addresses: "module 2 spur gear with keyway," "C45 steel pinion gear 12 tooth to 30 tooth," and "black oxide gear bore 10mm to 32mm."
Machined from C45 steel for a balance of machinability, tensile strength (typically 580–700 MPa), and wear resistance — suitable for continuous-duty drive applications.
The black oxide treatment reduces light reflection, lowers surface friction against mating gears, and provides a baseline layer of corrosion inhibition in dry or lightly oiled environments.
Cut to Module 2 (M2) standard with a 20° pressure angle, ensuring smooth meshing and interchangeability with any M2-rated rack or mating gear in your drivetrain.
Each variant includes a precision-cut keyway (4 mm, 5 mm, 6 mm, 8 mm, or 10 mm wide depending on bore size) that eliminates rotational slip under torque — no reliance on set screws alone.
Available bore diameters from 10 mm (0.39 in) to 32 mm (1.26 in) cover the most common shaft sizes used in servo motors, stepper motors, and gearbox output shafts in CNC and automation builds.
Choose from 12T through 30T to dial in your gear ratio. Pair with a larger driven gear or M2 rack to achieve the speed-to-torque tradeoff your application requires.
| Material | C45 Medium-Carbon Steel |
|---|---|
| Surface Treatment | Black Oxide |
| Module | 2 (M2) |
| Pressure Angle | 20° |
| Tooth Count | 12T, 13T, 14T, 15T, 16T, 17T, 18T, 19T, 20T, 21T, 22T, 23T, 24T, 25T, 26T, 27T, 28T, 30T |
| Bore Diameter Range | 10 mm – 32 mm (0.39 in – 1.26 in) |
| Keyway Width Range | 4 mm, 5 mm, 6 mm, 8 mm, 10 mm (varies by bore) |
| Outer Diameter (approx.) | 28 mm (12T) – 64 mm (30T) at M2 geometry |
| Face Width | See variant options |
| Hub Style | Flat (no extended hub) |
| Weight | See variant options |
| Quantity per Order | 1 pcs (default); multi-pack options available |
Tooth count determines your gear ratio when paired with a mating gear or rack. A lower tooth count (e.g., 12T) on the drive pinion produces more torque multiplication but lower output speed; a higher tooth count (e.g., 30T) gives a closer-to-1:1 ratio. Calculate your required ratio by dividing the driven gear's tooth count by the pinion's tooth count. For rack-and-pinion linear drives, the linear travel per revolution equals π × Module × Tooth Count (in mm).
Measure your motor or gearbox output shaft diameter precisely with a caliper. Select the bore that matches your shaft — the bore must not be larger than the shaft OD. The keyway width is fixed per bore size (e.g., 10–12 mm bore uses a 4 mm keyway; 14–17 mm bore uses a 5 mm keyway; 18–20 mm bore uses a 6 mm keyway; 22–25 mm bore uses an 8 mm keyway; 28–32 mm bore uses an 8–10 mm keyway). Confirm your shaft has a matching keyway slot cut to the same width and depth.
C45 steel has a typical tensile strength of 580–700 MPa and yield strength of approximately 305–450 MPa in the normalized condition. For Module 2 gears, the allowable tangential tooth load depends on face width, tooth count, and operating speed. These gears are suited for light-to-medium duty drives (e.g., CNC routers, indexing tables, robotic joints) operating at moderate speeds. For heavy shock loads or continuous high-torque applications, consider heat-treated or alloy steel alternatives.
Black oxide provides a thin magnetite layer that offers mild corrosion inhibition in dry or lightly oiled indoor environments. It is not a substitute for zinc plating or stainless steel in humid, wet, or chemically aggressive environments. For best results, apply a light machine oil or grease to the gear teeth and bore after installation to extend service life and maintain the coating's protective properties.
Yes — any Module 2 gear or rack with a 20° pressure angle will mesh correctly with this pinion. Module (M) is a standardized metric tooth size parameter; M2 gears are interchangeable regardless of manufacturer as long as the module and pressure angle match. Do not attempt to mesh M2 gears with Module 1, Module 1.5, Module 2.5, or any other module, as tooth profiles are incompatible and will cause rapid wear or binding.
The keyway is designed for use with a standard parallel key (not included) to transmit torque reliably. While a set screw can be added through the hub if your application allows drilling, relying solely on a press fit or set screw on a keyed bore is not recommended for reversing or high-torque loads, as it may cause fretting or shaft damage over time. Always use a properly fitted key for positive torque transmission.
Face width varies by tooth count and bore configuration. Please refer to the variant detail page or contact us to confirm the face width for your specific model before ordering, especially if you are matching an existing gear in a constrained space.
