2.5 Modul 45# Steel Spur Gears Pinion Gear Thick 25mm 10-80 Teeth For 3D CNC

Select your tooth count based on the gear ratio you need. Divide the driven gear's tooth count by the driving pinion's tooth count to get the reduction ratio. For example, a 10-tooth pinion meshing with a 40-tooth gear gives a 4:1 reduction. Also confirm that the resulting outer diameter fits within your housing clearance — refer to the Size(mm) variant field for OD values.

Bore diameter scales with tooth count: smaller pinions (10–15 teeth) use an 8 mm bore, mid-range gears (16–25 teeth) use a 10–12 mm bore, and larger wheels (26–80 teeth) use 14–20 mm bores. The exact bore for each variant is listed in the Size(mm) option as Bore × OD × Face-Width (e.g., 8×30×25 means 8 mm bore, 30 mm OD, 25 mm face width).

Yes. These gears conform to the Module 2.5 standard with a 20° pressure angle, which is the most common rack-and-pinion specification used in CNC routers and linear motion systems. They will mesh correctly with any ISO/DIN Mod 2.5 rack or mating gear from any supplier.

45# steel has a typical tensile strength of approximately 600–800 MPa and yield strength around 355 MPa in the normalised condition. For heavily loaded or high-cycle applications, consider whether a hardened or case-hardened variant would better suit your duty cycle. For light-to-medium CNC and 3D printer drives, 45# steel in the as-machined condition is generally adequate.

45# carbon steel is not inherently corrosion-resistant. For indoor, dry environments (typical of CNC workshops and 3D printer enclosures) this is not usually a concern. If your application involves moisture, coolant mist, or outdoor exposure, apply a light machine oil or consider a stainless or coated alternative. Wiping the gear with oil after installation is recommended as standard practice.

Yes — the smaller tooth-count variants (10–20 teeth) with 8–10 mm bores are well-suited to direct-drive and Bowden extruder gear trains. Confirm that the bore matches your motor shaft diameter and that the OD clears your extruder housing. The 25 mm face width provides ample contact area for the torque levels typical of filament extrusion.

The Size(mm) field follows the format Bore × Outer Diameter × Face Width, all in millimetres. For example, "12×55×25" means a 12 mm bore, 55 mm outer diameter, and 25 mm face width. Use the bore value to match your shaft, the OD to check housing clearance, and the face width (always 25 mm) to confirm axial alignment with your mating gear.