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When a gear slips mid-project or a mismatched module ruins a build, the frustration is real — especially for engineers, hobbyists, and makers who depend on precise power transmission. These spur gears and pinion gears are engineered for DIYers, CNC builders, robotics enthusiasts, and mechanical engineers who need consistent, repeatable gear mesh without compromise.
Each gear is machined from 45# medium carbon steel, offering a tensile strength typically in the 600–800 MPa range. Available in five module sizes — 1.5, 2.5, 3, 4, and 5 Mod — with tooth counts ranging from 12 to 100 teeth. Pitch diameters scale accordingly: a 1.5 Mod 12T gear measures approximately 18 mm (0.71 in) PD, while a 5 Mod 35T gear reaches 175 mm (6.89 in) PD. Bore diameter and hub dimensions vary by model — see variant options for specifics.
These flat spur gears suit a wide range of use cases: CNC router axis drives and rack-and-pinion setups, robotics joint actuators and servo transmission stages, and custom gearbox builds for conveyor systems or DIY lathe headstocks. Their standardized module sizing makes them interchangeable with other metric-module gears across your build.
Machined from 45# steel for solid load-bearing capacity and wear resistance across continuous-duty transmission applications.
Choose from Mod 1.5, 2.5, 3, 4, or 5 to match your existing gear train. Standardized metric module ensures accurate meshing with compatible gears.
From compact 12-tooth pinions to large 100-tooth spur gears, covering a broad gear ratio range for speed reduction or torque multiplication.
Standard spur gear tooth form transmits power between parallel shafts with minimal noise and predictable load distribution.
Drop-in compatible with any same-module metric gear — ideal for replacing worn gears or expanding existing gear trains without custom machining.
Trusted in CNC axis drives, robotic joints, conveyor systems, and custom gearbox builds where dimensional accuracy and material consistency matter.
| Material | 45# Medium Carbon Steel |
|---|---|
| Gear Type | Spur Gear (Flat) |
| Module (Mod) | 1.5 / 2.5 / 3 / 4 / 5 |
| Tooth Count | 12 – 100 Teeth (varies by variant) |
| Pressure Angle | 20° (standard metric) |
| Pitch Diameter | See variant options |
| Bore Diameter | See variant options |
| Hub / Face Width | See variant options |
| Surface Finish | See variant options |
| Shaft Compatibility | Parallel shaft, metric bore |
| Application | CNC, robotics, conveyor, gearbox, DIY machinery |
| Quantity per Order | 1 piece |
The module (Mod) must match between meshing gears — a Mod 3 gear only meshes with another Mod 3 gear. Tooth count determines your gear ratio: divide the driven gear teeth by the driving gear teeth to get the ratio. For example, a 60T gear driven by a 20T pinion gives a 3:1 reduction. Select the module that fits your center distance and torque requirements, then choose tooth counts to achieve your target ratio.
45# steel (also written as 45 steel or C45) is a medium carbon steel widely used in mechanical components. It typically has a tensile strength of 600–800 MPa in the normalized condition and can be heat-treated (quenched and tempered) to achieve higher hardness. It offers a good balance of machinability, strength, and wear resistance — making it a standard choice for spur gears in moderate-load applications.
Yes — as long as the other gear shares the same module and pressure angle (20°, which is the international standard for metric spur gears). Module is a standardized metric measurement, so a Mod 3 gear from any manufacturer will mesh correctly with these Mod 3 gears. Always verify the module, pressure angle, and bore diameter before combining gears from different sources.
45# steel has moderate corrosion resistance. For outdoor or humid environments, we recommend applying a rust-inhibiting coating, grease, or oil after installation. If your application requires higher corrosion resistance, consider stainless steel or nylon gears instead. These gears are best suited for indoor machinery, enclosed gearboxes, or applications where lubrication is maintained.
To identify the module of an existing gear, count the number of teeth and measure the outer diameter (tip diameter) in millimeters. Use the formula: Module = Tip Diameter ÷ (Tooth Count + 2). For example, a gear with 30 teeth and a 96 mm tip diameter gives Module = 96 ÷ 32 = 3. Then match the bore diameter and face width to your shaft and housing dimensions.
Bore dimensions vary by variant — please check the specific variant details or contact us to confirm the bore diameter before ordering. Some variants may require additional machining (such as keyway cutting or bore enlargement) to fit your specific shaft. If you need a custom bore size, please reach out before purchasing so we can advise on the best option.
For most applications, a light machine oil or gear grease applied to the tooth flanks is sufficient. For higher-speed or higher-load applications, use an EP (extreme pressure) gear oil. Lubrication reduces wear, lowers operating temperature, and extends gear life. Re-lubricate periodically based on your duty cycle and operating conditions.
