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When a stripped or undersized gear brings your CNC router, robotic arm, or custom drive system to a halt, finding an exact-spec replacement fast is everything. These 2M and 2.5M module spur gears are machined from 45# medium-carbon steel and are sized to fit the most common DIY, maker, and light-industrial gear trains — giving hobbyists, engineers, and repair technicians a reliable drop-in solution without custom fabrication.
Each gear is CNC-turned from solid 45# steel billet. The 2M (Module 2) variant has a tooth thickness of 20 mm (approx. 0.79 in) and is available from 10T to 100T. The 2.5M (Module 2.5) variant has a tooth thickness of 25 mm (approx. 0.98 in) and spans 10T to 76T. Bore diameter varies by tooth count — see variant options for exact bore specs. Both series share a standard involute tooth profile for smooth, low-noise meshing.
Typical use cases include CNC machine axis drives and rack-and-pinion setups, 3D printer extruder and Z-axis gear trains, robotics joint actuators requiring a compact spur gear for torque transmission, and DIY go-kart or electric vehicle reduction stages where a steel pinion gear with a precise module is required.
| Module | 2M / 2.5M (select variant) |
|---|---|
| Tooth Count | 10T – 100T (2M); 10T – 76T (2.5M) |
| Tooth Thickness (Face Width) | 2M: 20 mm (0.79 in) / 2.5M: 25 mm (0.98 in) |
| Material | 45# Medium-Carbon Steel |
| Tooth Profile | Standard Involute |
| Pressure Angle | 20° |
| Bore Diameter | See variant options |
| Keyway | See variant options |
| Surface Finish | Natural steel (uncoated) |
| Quantity per Order | 1 Piece |
The module number defines the size of each tooth. A 2.5M gear has larger, stronger teeth than a 2M gear of the same tooth count. Match the module to your existing rack, pinion, or mating gear — mixing modules will prevent proper meshing. If you are designing from scratch, choose 2.5M for higher torque loads and 2M for more compact, lighter-duty drives.
Gear ratio equals the tooth count of the driven gear divided by the tooth count of the driving gear. For example, pairing a 20T pinion with a 60T gear gives a 3:1 reduction. With tooth counts from 10T to 100T available in the 2M series, you can achieve a wide range of ratios in a single mesh or compound gear train.
45# steel offers a tensile strength of approximately 600–700 MPa in the normalized condition, making it suitable for moderate-load gear applications such as CNC drives, robotics joints, and light power transmission. For very high-torque or high-speed industrial applications, consider whether additional heat treatment or a higher-alloy steel would be appropriate for your load case.
45# carbon steel is not inherently corrosion-resistant. For use in humid or outdoor environments, we recommend applying a light machine oil, grease, or a rust-inhibiting coating after installation. If corrosion resistance is a primary requirement, consider stainless steel or nylon gear alternatives.
Bore diameter varies by tooth count and module. Please check the variant detail or contact us to confirm the bore size for your specific tooth count before ordering. You can also have the bore enlarged by a local machine shop if needed, as 45# steel machines readily.
Yes. A Module 2 spur gear will mesh correctly with a Module 2 rack, and a Module 2.5 spur gear with a Module 2.5 rack. This makes these gears well-suited for CNC router axes, linear actuators, and rack-and-pinion steering systems. Ensure the rack pressure angle (typically 20°) matches the gear.
Each order is for 1 piece. If your drive system requires a matched pair or a compound gear set, simply add the required quantity to your cart or place separate orders for each tooth count you need.
