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When your motor drive system demands tight tolerances and consistent mesh quality, an undersized or poorly machined pinion gear becomes the weakest link in the chain. Engineers, robotics builders, and CNC hobbyists who need a reliable Module 1 spur pinion gear with a broad selection of tooth counts and bore diameters will find this range covers virtually every common configuration in a single listing.
Each gear is machined from 45# carbon steel — a medium-carbon structural steel known for its balance of hardness and machinability. The module is 1M (metric), with tooth counts spanning 10T through 46T and bore diameters from 4 mm (0.157 in) up to 25 mm (0.984 in). Select step-bore variants are also available for applications requiring a shoulder or hub register. Outer diameter scales with tooth count: approximately 12 mm (0.47 in) for 10T up to approximately 48 mm (1.89 in) for 46T.
Typical use cases include DC motor pinion drives in wheeled robots and AGVs, stepper motor output stages in desktop CNC routers and 3D printer extruder gearboxes, and general-purpose speed-reduction or torque-multiplication stages in light industrial automation. The wide bore range — including 6.35 mm (1/4 in) and 12.7 mm (1/2 in) imperial-standard options — makes these gears compatible with both metric and fractional motor shafts.
| Module | 1M (Metric Module 1) |
|---|---|
| Material | 45# Carbon Steel |
| Tooth Count Range | 10T – 46T |
| Bore Diameter Range | 4 mm – 25 mm (see variant options) |
| Step-Bore Options | Available on select tooth counts (see variant options) |
| Outer Diameter (approx.) | ~12 mm (10T) to ~48 mm (46T) |
| Pressure Angle | See variant options |
| Face Width | See variant options |
| Hub / Step Diameter | See variant options |
| Surface Treatment | See variant options |
| Weight | See variant options |
The tooth count determines your gear ratio when meshed with a mating gear. Divide the driven gear's tooth count by the pinion's tooth count to get the reduction ratio. For example, a 10T pinion driving a 40T gear gives a 4:1 reduction. Choose a lower tooth count for higher speed reduction and more torque; choose a higher tooth count for a closer-to-1:1 ratio.
Measure your motor shaft diameter with a caliper. Select the bore that matches your shaft exactly — a bore that is too large will cause runout and noise. If your shaft is a fractional size such as 1/4 in (6.35 mm) or 1/2 in (12.7 mm), those bore options are available in this listing. For setscrew retention, the bore should be a close sliding fit on the shaft.
A step-bore gear has a larger-diameter hub shoulder machined into the gear body. This shoulder can register against a bearing face, a motor flange, or a housing bore to control axial positioning. If your design requires the gear to be located axially by a shoulder rather than a setscrew or retaining ring alone, choose a step-bore variant. If axial location is handled by other means, a standard bore variant is sufficient.
Yes. All gears in this listing are Module 1 (1M) metric standard. They will mesh correctly with any other Module 1 spur gear, helical gear (same helix angle), or rack regardless of brand, provided the pressure angle also matches. The standard pressure angle for Module 1 gears is typically 20°; confirm your mating gear's pressure angle before assembly.
45# carbon steel (approximately equivalent to AISI 1045) has a tensile strength typically in the range of 600–800 MPa in the normalized condition and can be heat-treated to higher hardness for demanding applications. It is significantly stronger than aluminum or plastic gears and is the standard material for motor pinions in robotics, CNC, and light industrial drives. For very high-load or high-speed applications, consider whether additional surface hardening is required.
45# steel gears are susceptible to surface oxidation in humid environments. For indoor, dry applications a light machine oil or grease on the tooth flanks is sufficient. For outdoor or high-humidity environments, consider applying a corrosion-inhibiting grease or a surface coating after installation. Lubrication also reduces tooth wear and noise, so periodic re-greasing is recommended for continuous-duty applications.
These gears are designed for motor pinion use. The bore is typically machined to an H7 or similar close-tolerance fit suitable for a light press-fit or a setscrew/grub-screw retention. For a true interference press-fit, verify the bore tolerance against your shaft tolerance class. If in doubt, contact us to confirm bore tolerance for your specific variant before ordering.
