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When your CNC router, robotic arm, or automation drive train demands a gear that fits precisely and holds up under continuous load, a poorly toleranced or soft-metal substitute creates costly downtime. Engineers, makers, and small-batch manufacturers who need a reliable module 1 spur gear with a stepped hub bore will find this series purpose-built for that exact challenge.
Each gear is machined from 45# medium-carbon steel and finished with a blackening (black oxide) surface treatment that reduces surface friction and provides baseline corrosion resistance. The stepped hub design allows the gear to seat securely against a shoulder on the shaft, preventing axial migration without additional collars. Tooth counts range from 12T to 52T, and bore diameters span 5 mm (0.197 in) to 16 mm (0.630 in), covering the most common motor shaft sizes in this module class. Outer diameter scales proportionally with tooth count: a 12T gear measures approximately 14 mm (0.551 in) OD, while a 52T gear reaches approximately 54 mm (2.126 in) OD.
Typical use cases include module 1 spur gear for stepper motor drives in desktop CNC machines, gear-reduction stages in small robotic joints requiring a 45 steel spur gear with step bore, and replacement gearing in light industrial conveyor or indexing mechanisms where a blackening spur gear with stepped hub is specified.
45# Medium-Carbon Steel Construction
Machined from 45# steel for a balance of machinability and load-bearing strength, suitable for continuous-duty gear drives in automation and robotics.
Blackening Surface Treatment
Black oxide finish reduces bare-metal friction, provides mild corrosion resistance, and gives a uniform appearance across the full tooth profile.
Stepped Hub Design
The integrated step on the hub bore allows the gear to register against a shaft shoulder, eliminating axial float without requiring additional retaining hardware.
Wide Tooth Count Range: 12T–52T
Twenty-five tooth-count options in a single series let you dial in the exact gear ratio needed for your drive stage without custom machining.
Multiple Bore Diameters: 5–16 mm
Ten bore size options — 5, 6, 6.35, 7, 8, 10, 12, 14, 15, and 16 mm — cover standard metric and fractional motor shaft diameters used in stepper and servo applications.
Module 1 Standard Tooth Profile
Conforms to the Module 1 gear standard, ensuring direct interchangeability with any Module 1 rack, pinion, or mating spur gear in your existing drivetrain.
| Module | 1 |
|---|---|
| Tooth Count (T) | 12T, 13T, 14T, 15T, 16T, 18T, 20T, 22T, 24T, 25T, 26T, 28T, 30T, 32T, 33T, 35T, 36T, 38T, 40T, 42T, 44T, 45T, 48T, 50T, 52T |
| Bore Diameter | 5 mm, 6 mm, 6.35 mm, 7 mm, 8 mm, 10 mm, 12 mm, 14 mm, 15 mm, 16 mm |
| Outer Diameter (OD) | See variant options (OD = (T + 2) × 1 mm; e.g., 12T ≈ 14 mm, 52T ≈ 54 mm) |
| Hub Style | Stepped hub |
| Material | 45# medium-carbon steel |
| Surface Treatment | Blackening (black oxide) |
| Pressure Angle | 20° |
| Tooth Profile | Involute spur |
| Hub Length | See variant options |
| Keyway | Contact us to confirm |
| Package Quantity | 1 piece per order |
Tooth count determines your gear ratio. Divide the driven gear tooth count by the driving gear tooth count to get the ratio. For example, pairing a 12T driver with a 36T driven gear gives a 3:1 reduction. Select a tooth count that achieves your target ratio while keeping the outer diameter within your housing clearance. Use the formula OD = (T + 2) × module (1 mm) to estimate outer diameter for each option.
Measure your motor or gearbox output shaft diameter with a caliper and select the matching bore. Common stepper motor shafts are 5 mm and 6.35 mm (1/4 in); servo motors often use 6 mm, 8 mm, or 10 mm shafts. If your shaft diameter falls between listed sizes, a bore slightly larger than the shaft can be used with a set screw or shaft collar, but a matched bore is recommended for concentricity.
The stepped hub creates a shoulder that registers against a mating surface on the shaft or housing, preventing the gear from sliding axially during operation. This is particularly useful in applications where thrust loads or vibration could cause a plain-bore gear to migrate. If your shaft has a corresponding shoulder or snap-ring groove, the stepped hub provides a clean, hardware-free axial constraint.
45# steel (equivalent to C45 / SAE 1045) has a typical tensile strength of approximately 600–800 MPa in the normalized condition. It is well-suited for light-to-medium duty gear drives such as CNC axis drives, robotic joints, and indexing mechanisms. For very high-torque or impact-load applications, consider whether a heat-treated or alloy-steel gear would be more appropriate. Contact us if you need specific load capacity data for your tooth count and module.
Black oxide (blackening) provides mild corrosion resistance by converting the surface iron to magnetite, which is less reactive than bare steel. It is suitable for indoor, low-humidity environments and light oil-lubricated applications. For outdoor use, wet environments, or food-adjacent applications, additional lubrication or a corrosion-resistant coating is recommended. Applying a light machine oil after installation will significantly extend the finish life.
Yes. Any gear labeled Module 1 (M1) with a 20° pressure angle will mesh correctly with this gear series. Verify that your existing rack or mating gear is also Module 1 — mixing modules (e.g., M1 with M1.5) will result in incorrect tooth engagement and rapid wear. If you are unsure of your existing gear's module, measure the outer diameter and count the teeth: Module = OD ÷ (T + 2).
Each listing is sold as 1 piece (1Pcs). If you need multiple gears of the same or different specifications, simply add the required quantity to your cart or place separate orders for different tooth count and bore combinations. For larger volume requirements or project-based procurement, please contact us directly to discuss availability and pricing.
