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When your CNC router, robotic arm, or automation drive demands a gear that meshes cleanly and holds its tolerance under load, a mismatched or undersized pinion becomes the weakest link in the entire system. These C45 medium-carbon steel spur gears are engineered for makers, machine builders, and automation engineers who need a reliable, off-the-shelf solution across a wide range of module and tooth-count combinations.
Each C45 steel spur gear is machined to standard metric module dimensions — available in Module 1, 1.5, 2, 2.5, 3, 4, and 5 — with tooth counts spanning 12 to 160 teeth depending on the module selected. The flat (plain bore) hub style allows custom bore sizing on a lathe or with a broach, giving you full control over shaft fit. Outer diameter scales directly with module and tooth count per the standard formula OD = (Z + 2) × m, typically ranging from approximately 14 mm (0.55 in) for a Mod 1 / 12T up to roughly 810 mm (31.9 in) for a Mod 5 / 160T equivalent.
Typical use cases include CNC router X/Y axis drives and rack-and-pinion systems, stepper and servo motor pinions in 3D printer gantries and pick-and-place machines, and reduction gear trains in conveyor systems, rotary indexers, and DIY robotics platforms requiring precise angular positioning.
Machined from C45 (equivalent to 1045) medium-carbon steel for a balance of machinability, surface hardness after heat treatment, and tensile strength — suitable for moderate-to-high torque drives.
Seven module sizes (1, 1.5, 2, 2.5, 3, 4, 5) with tooth counts from 12 to 160 teeth, covering small precision pinions through large reduction gears in a single product listing.
Manufactured to the ISO/DIN metric gear standard with a 20° pressure angle, ensuring direct interchangeability with any conforming mating gear, rack, or gearbox of the same module.
The flat plain bore allows you to machine the bore to your exact shaft diameter, add a keyway, or press-fit a bushing — giving maximum flexibility for motor pinion and drive shaft applications.
Outer diameter follows the standard formula OD = (Z + 2) × m, so you can calculate the exact gear diameter for your drive geometry before ordering — no surprises during assembly.
Suitable for CNC routers, 3D printer gantries, robotic arms, conveyor drives, rotary indexers, and DIY automation projects requiring a reliable, standardized metric spur gear.
| Material | C45 medium-carbon steel (equiv. 1045) |
|---|---|
| Gear Type | Spur gear (straight tooth) |
| Module (m) | 1 / 1.5 / 2 / 2.5 / 3 / 4 / 5 (see variant options) |
| Tooth Count (Z) | 12 – 160 teeth (see variant options) |
| Pressure Angle | 20° |
| Outer Diameter | (Z + 2) × m mm — see variant options |
| Face Width | See variant options |
| Bore Style | Plain bore (flat hub) — custom machining required |
| Bore Diameter | See variant options |
| Surface Finish | Machined, natural steel |
| Standard | ISO/DIN metric module |
| Quantity | 1 pc per order (multi-pack options available) |
The module (m) determines the tooth size and pitch — larger modules mean larger, stronger teeth. Match the module to your mating gear or rack. The tooth count (Z) determines the gear ratio and the outer diameter: OD = (Z + 2) × m. Calculate your required OD and gear ratio first, then select the module and tooth count combination that fits your drive geometry.
These gears are supplied with a plain (flat) bore. The bore diameter varies by module and tooth count — please refer to the variant details or contact us to confirm the as-supplied bore size. Because the bore is plain, you can machine it to your exact shaft diameter, add a keyway, or install a set-screw collar using standard lathe or broaching operations.
Yes. These spur gears are manufactured to the standard ISO/DIN metric module specification with a 20° pressure angle. They will mesh correctly with any conforming mating spur gear, rack, or gearbox component of the same module and pressure angle, regardless of brand or source.
C45 (equivalent to SAE 1045) is a medium-carbon steel with a tensile strength of approximately 600–800 MPa in the normalized condition. It is well-suited for moderate-to-high torque drives in CNC, robotics, and automation. For very high-load or high-speed applications, consider surface hardening (induction hardening or case hardening) after machining the bore to your shaft size.
C45 steel is not stainless and will oxidize if left unprotected in humid environments. For indoor CNC and automation use, applying a light machine oil or grease to the tooth flanks during operation provides adequate protection and lubrication. For outdoor or wet environments, consider a zinc-phosphate primer coat or periodic re-greasing.
Yes — the plain bore design is specifically intended for motor pinion use. You will need to machine or have machined the bore to match your motor shaft diameter (e.g., 5 mm, 6 mm, 8 mm, 10 mm, etc.) and add a flat, keyway, or set-screw as required by your motor shaft style. Smaller modules (1, 1.5, 2) are most commonly used as motor pinions in CNC and 3D printer applications.
Face width varies by module and tooth count. As a general guideline, face width is typically 8–10 times the module for standard spur gears (e.g., approximately 8–10 mm for Mod 1, 16–20 mm for Mod 2). Please contact us to confirm the exact face width for your selected variant before ordering if this dimension is critical to your design.
