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When a mismatched or undersized gear causes slippage, noise, or premature failure in your motion-control build, the fix starts with choosing the right module and tooth count. These 45# steel spur gears are designed for engineers, makers, and small-shop builders who need reliable, dimensionally consistent pinion gears across a wide range of drive configurations.
Each gear is machined from 45# carbon steel and is available in Module 2, 2.5, 3, 4, and 5, with tooth counts ranging from 10T to 63T and face widths of 20 mm to 40 mm (approximately 0.79 in to 1.57 in). The bore diameter and keyway dimensions vary by module and tooth count — see variant options for exact bore specs.
Typical use cases include CNC router axis drives requiring a compact 2M or 2.5M pinion gear, robotic arm joints needing a 3M or 4M spur gear with higher torque capacity, and industrial automation conveyor or indexing systems where a 5M metal gear provides the load-bearing surface area needed for continuous-duty cycles.
Machined from 45# medium-carbon steel for a balance of hardness, toughness, and machinability — suitable for moderate-to-high load drive applications.
Available in Mod 2, 2.5, 3, 4, and 5 with tooth counts from 10T to 63T, covering compact pinion gears up to large-diameter spur gears in a single product family.
Choose the face width that matches your load and space envelope — thicker faces distribute torque over a wider contact zone, reducing tooth stress in heavy-duty cycles.
Cut to the industry-standard 20° pressure angle for smooth meshing, reduced backlash, and direct interchangeability with standard metric racks and mating gears.
Hobbed tooth profiles maintain consistent pitch diameter and tooth spacing across the full tooth count range, supporting reliable power transmission in indexing and positioning systems.
Suited for CNC routers, 3D printer extruder drives, robotic joints, conveyor indexers, and general automation equipment where a standard metric spur gear is specified.
| Material | 45# Carbon Steel |
|---|---|
| Module (Mod) | 2 / 2.5 / 3 / 4 / 5 |
| Tooth Count | 10T – 63T (varies by module; see variant options) |
| Pressure Angle | 20° |
| Face Width (Thickness) | 20 mm – 40 mm (0.79 in – 1.57 in) |
| Bore Diameter | See variant options |
| Keyway | See variant options |
| Surface Finish | Natural steel (uncoated) |
| Tooth Profile | Hobbed, involute |
| Gear Type | External spur gear (pinion) |
The module must match the mating gear or rack exactly. Mod 2 and 2.5 are common in compact CNC and 3D printer drives; Mod 3 suits medium-load robotics; Mod 4 and 5 are used in heavier industrial drives. Check your existing gear or rack specification before selecting.
Divide the desired gear ratio by the tooth count of your motor pinion to find the mating gear tooth count. For example, a 3:1 ratio with a 10T motor pinion requires a 30T output gear. This product covers 10T–63T, giving you flexibility across a wide ratio range.
45# carbon steel has a tensile strength of approximately 600–800 MPa in the normalized condition, making it suitable for moderate-to-high torque drives. For very high-shock or continuous heavy-duty applications, consider whether a heat-treated or alloy steel gear is more appropriate for your specific load cycle.
45# carbon steel is not inherently corrosion-resistant. For indoor, dry environments this is typically acceptable. If your application involves moisture, coolant, or outdoor exposure, apply a light machine oil coating or consider a stainless or coated alternative.
The bore diameter varies by module and tooth count. Check the variant detail page or contact us to confirm the bore size for your selected Mod-Teeth combination before ordering. Measure your shaft diameter with calipers to ensure a proper fit.
Yes — as long as both the gear and rack share the same module (Mod 3) and pressure angle (20°), they will mesh correctly regardless of brand. Always confirm the pressure angle specification with your rack supplier.
A wider face distributes the tooth load over a larger contact area, reducing stress and wear under higher torque. Choose 20 mm for light-duty or space-constrained builds and 40 mm for heavier loads or continuous-duty cycles. Match the face width to your mating gear where possible.
