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When a stripped or undersized gear brings your stepper motor project, CNC axis, or robotics build to a halt, finding an exact-fit replacement wastes hours. Makers, engineers, and hobbyists who need a reliable Module 1 spur gear with a specific bore and tooth count can select precisely the combination they need from this listing — no custom machining required.
Each gear is machined from 45# carbon steel, offering a balance of hardness and machinability suited to moderate-load power transmission. The Module 1 (1 Mod) tooth profile is the standard metric gear module, with an outer diameter that scales directly with tooth count — ranging from approximately 12 mm (0.47 in) for 10T up to approximately 52 mm (2.05 in) for 50T. Bore options span 4 mm to 25 mm (0.16 in – 0.98 in) to accommodate common motor shaft sizes including NEMA 17 (5 mm), NEMA 23 (6.35 mm), and larger servo shafts.
Typical use cases include stepper motor pinion drives in 3D printers and laser cutters, rack-and-pinion linear motion systems, small gearbox reduction stages, and educational robotics platforms where a standard metric spur gear is required.
| Module | 1 (Mod 1) |
|---|---|
| Material | 45# Carbon Steel |
| Tooth Count (T) | 10T – 50T (see variant options) |
| Bore Diameter | 4 mm – 25 mm (see variant options) |
| Outer Diameter | Approx. (T + 2) × 1 mm — e.g., 12 mm for 10T, 52 mm for 50T |
| Pressure Angle | 20° |
| Gear Type | Spur (straight tooth) |
| Hub Style | See variant options |
| Face Width | See variant options |
| Surface Finish | Natural steel / lightly deburred |
| Keyway | Contact us to confirm |
| Set Screw | Contact us to confirm |
The tooth count determines your gear ratio. Divide the driven gear teeth by the driving gear teeth to get the ratio. For example, a 10T pinion driving a 30T gear gives a 3:1 reduction. Choose a tooth count that achieves your target speed or torque ratio when paired with your mating gear or rack.
NEMA 17 stepper motors typically have a 5 mm output shaft. Select the 5 mm bore variant. If your motor has a flat (D-shaft), you may need to add a set screw or use a shaft coupler — please contact us to confirm set screw availability for your chosen variant.
NEMA 23 motors commonly use a 6.35 mm (1/4 inch) or 8 mm shaft. Both bore sizes are available in this listing. Measure your motor shaft diameter before selecting to ensure a proper fit.
45# carbon steel (equivalent to AISI 1045) has a tensile strength of approximately 600–800 MPa in its normalized state. It is well-suited for moderate-load spur gear applications such as 3D printer drives, small CNC machines, and robotics. For very high-torque or high-speed industrial applications, consider hardened or alloy steel gears.
Yes. Module 1 is a standardized metric gear module. Any two Module 1 gears with the same pressure angle (20°) will mesh correctly regardless of tooth count. This gear is compatible with Module 1 racks, pinions, and mating spur gears from any manufacturer following the metric module standard.
The bore is machined to a standard H7 tolerance suitable for shaft fits. Keyway availability varies by variant — please contact us to confirm whether a keyway or set screw is included for your specific tooth count and bore combination.
For a Module 1 gear, the outer (tip) diameter is calculated as: OD = (T + 2) × Module = (T + 2) mm. For example: 10T → 12 mm, 20T → 22 mm, 30T → 32 mm, 40T → 42 mm, 50T → 52 mm. Use this formula to verify the gear fits within your assembly envelope before ordering.
