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When a stripped or undersized gear brings your CNC router, robotic arm, or custom drive train to a halt, you need a replacement that holds tolerance under load. These 2.5 module spur gears are engineered for hobbyists, prototype builders, and small-batch manufacturers who demand consistent mesh accuracy without sourcing from a full industrial catalog.
Each gear is machined from 45# medium-carbon steel — a material known for its balanced hardness and machinability — and features a 25 mm (approximately 0.984 in) face width. The tooth count spans from 10 T to 47 T, giving you a pitch circle diameter range of roughly 25 mm (0.984 in) for the 10-tooth variant up to approximately 117.5 mm (4.626 in) for the 47-tooth variant. Bore diameter varies by tooth count; confirm your shaft size against the variant listing before ordering.
Typical use cases include motor-to-gearbox pinion stages in DIY CNC machines, speed-reduction transmission assemblies in robotics and automation rigs, and replacement drive gears in 3D printer extruder or axis systems requiring a 2.5 mod standard pitch.
| Module | 2.5 |
|---|---|
| Pressure Angle | 20° |
| Tooth Count Range | 10 T – 47 T (select variant) |
| Face Width (Thickness) | 25 mm (≈ 0.984 in) |
| Pitch Circle Diameter | 25 mm – 117.5 mm (varies by tooth count) |
| Material | 45# Medium-Carbon Steel |
| Surface Finish | See variant options |
| Bore Diameter | See variant options |
| Keyway | See variant options |
| Hub Diameter | See variant options |
| Overall Diameter (OD) | See variant options |
| Weight | See variant options |
| Gear Standard | ISO/DIN Module System |
Determine your required gear ratio first: divide the driver tooth count by the driven tooth count. For example, pairing a 10 T pinion with a 30 T gear gives a 3:1 reduction. Select the tooth count that achieves your target ratio while keeping the center distance compatible with your housing or frame design. Center distance = (T1 + T2) × Module / 2.
Bore diameter varies by tooth count and is listed in the individual variant details. Please check the variant specification or contact us to confirm the bore size before ordering, especially if you need a specific shaft fit.
45# steel provides solid load-bearing capacity for moderate-to-high torque in intermittent or continuous-duty cycles. For very high-speed or heavy industrial loads, consider whether a heat-treated or case-hardened variant is more appropriate for your duty cycle. These gears are well-suited for robotics, CNC, and maker-grade machinery.
45# carbon steel has moderate corrosion resistance. For environments with moisture, coolant exposure, or outdoor use, we recommend applying a light machine oil or grease coating during installation and periodically during service. If corrosion resistance is a primary requirement, consider stainless steel or plastic gear alternatives.
Yes — as long as your existing gears conform to the standard Module 2.5 pitch with a 20° pressure angle, these gears will mesh correctly. Module and pressure angle must match between mating gears; tooth count only affects ratio and center distance.
A pinion is simply the smaller of two meshing spur gears — typically the driver gear mounted on a motor shaft. In this listing, the lower tooth-count variants (10 T–15 T) are commonly used as pinion gears, while larger tooth-count variants serve as the driven gear in a reduction stage. Both are standard spur gears with straight, parallel teeth.
Mounting method (keyway, set screw, or interference fit) depends on the specific variant. Please check the variant detail page or contact us to confirm the hub configuration for your selected tooth count before finalizing your design.
