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When a stripped or mismatched gear brings your build to a halt, you need a replacement you can trust to mesh cleanly and hold torque. These 1 module spur gears are designed for hobbyists, robotics builders, and small-machine engineers who demand dimensional accuracy and consistent tooth geometry across every unit they install.
Each 1 module spur gear is machined from 45# medium-carbon steel, delivering a solid balance of hardness and machinability. The range covers 10 to 25 teeth with bore diameters from 4 mm (0.16 in) to 15 mm (0.59 in), and an outer diameter that scales proportionally with tooth count — typically 12 mm (0.47 in) for a 10T gear up to 27 mm (1.06 in) for a 25T gear. Face width is typically 10 mm (0.39 in) across the range.
Typical use cases include DC motor pinion drives in wheeled robots, rack-and-pinion linear actuators for CNC router Z-axes, and multi-stage reduction gearboxes in small conveyor systems. The standardized 1 Mod tooth profile ensures interchangeability with any other Module 1 rack or mating gear in your drivetrain.
| Material | 45# Medium-Carbon Steel |
|---|---|
| Module | 1 (Mod 1) |
| Pressure Angle | 20° |
| Teeth Count Range | 10 / 12 / 14 / 15 / 16 / 17 / 18 / 19 / 20 / 25 Teeth |
| Bore Diameter | 4 mm / 5 mm / 6 mm / 6.35 mm / 7 mm / 8 mm / 10 mm / 12 mm / 14 mm / 15 mm |
| Outer Diameter (OD) | See variant options (scales with tooth count; typically 12–27 mm) |
| Face Width | Typically 10 mm (0.39 in) |
| Hub Diameter | See variant options |
| Hub Length | See variant options |
| Set Screw | See variant options |
| Surface Finish | Machined, natural steel |
| Pack Quantity | 1 / 2 / 5 / 10 Pcs (select above) |
The gear ratio between two meshing gears equals the ratio of their tooth counts. For example, pairing a 10-tooth pinion with a 20-tooth gear gives a 2:1 reduction. Choose a smaller tooth count (10–15T) for higher speed output and a larger count (18–25T) when you need more torque multiplication or a gentler reduction ratio.
Measure your motor shaft diameter with calipers before ordering. Common DC and stepper motor shafts run 4 mm, 5 mm, 6 mm, 6.35 mm (1/4 in), 8 mm, 10 mm, and 12 mm. Select the bore that matches your shaft exactly. If your shaft has a flat (D-cut), confirm the set screw position aligns with it for a secure fit.
45# steel offers a tensile strength typically in the 600–800 MPa range after standard heat treatment, making it suitable for moderate continuous loads in robotics, small conveyors, and hobby CNC machines. For very high-torque or shock-load environments, consider whether a hardened or alloy-steel gear would be more appropriate for your specific torque and RPM requirements.
45# carbon steel is not inherently corrosion-resistant. For indoor, dry environments this is generally not a concern with normal use. If your application involves moisture, humidity, or outdoor exposure, apply a light machine oil or grease to the gear teeth and bore, or consider a stainless-steel alternative for long-term protection.
Yes — Module 1 is an internationally standardized tooth profile (ISO 54 / DIN 780). Any Mod 1 spur gear or rack from any manufacturer will mesh correctly with these gears, provided the pressure angle is also 20°. Always verify the pressure angle specification of your existing gears before mixing brands.
Order 1–2 pieces for prototyping or single-axis builds where you need to validate fit and ratio before committing. Order 5 pieces when building a small batch of identical assemblies or when you want a spare on hand. Order 10 pieces for production runs, classroom kits, or multi-axis machines where the same gear size appears repeatedly.
For a Module 1 spur gear, the theoretical outer diameter (addendum circle) equals (Teeth + 2) × Module. So a 10T gear has an OD of approximately 12 mm, a 15T gear approximately 17 mm, a 20T gear approximately 22 mm, and a 25T gear approximately 27 mm. Actual machined dimensions may vary slightly; contact us to confirm if tight housing clearances are critical.
