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When a worn or undersized pinion gear causes backlash, skipped steps, or premature drivetrain failure on your CNC router or 3D printer, the root cause is almost always inadequate material strength or imprecise tooth geometry. Engineers, makers, and machine builders who demand repeatable, low-noise motion need a spur gear that holds tolerance under continuous load — and that is exactly what these 5 Mod 45# steel pinion gears are designed to deliver.
Each gear is machined from 45# medium-carbon steel, offering a balanced combination of tensile strength and machinability. The face (tooth) width is a consistent 40 mm (approx. 1.57 in), and the module is 5 (Module 5 / Mod 5), with available tooth counts ranging from 10 to 18 teeth. Corresponding pitch circle diameters range from 50 mm (≈1.97 in) for the 10-tooth variant up to 90 mm (≈3.54 in) for the 18-tooth variant.
Typical applications include CNC gantry drives and rack-and-pinion linear motion systems, heavy-duty 3D printer extruder and Z-axis drives requiring high torque transmission, and industrial conveyor or rotary indexing mechanisms where consistent gear mesh and low backlash are critical.
| Material | 45# Medium-Carbon Steel |
|---|---|
| Module (Mod) | 5 |
| Tooth Count Options | 10, 11, 12, 13, 14, 15, 16, 17, 18 Teeth |
| Face Width (Thickness) | 40 mm (1.57 in) |
| Pitch Circle Diameter Range | 50 mm – 90 mm (1.97 in – 3.54 in) |
| Pressure Angle | 20° (standard) |
| Bore Diameter | See variant options |
| Keyway | See variant options |
| Surface Finish | See variant options |
| Gear Type | Spur Gear (Pinion) |
| Compatible Standard | Module 5 (ISO/DIN) |
| Typical Applications | CNC routers, 3D printers, rack-and-pinion drives, industrial conveyors |
The tooth count determines your gear ratio and pitch circle diameter. Fewer teeth (e.g., 10T) give a smaller pinion and higher speed reduction when meshed with a larger gear; more teeth (e.g., 18T) increase the pitch circle and reduce the ratio. Calculate your required ratio first, then select the tooth count that achieves it within your available center-distance constraints.
Module (Mod) is the international standard for gear tooth size — it equals the pitch circle diameter divided by the number of teeth. Module 5 gears will mesh correctly with any other Module 5 gear, rack, or pinion that shares the same pressure angle (20°). They are not interchangeable with Module 4, Module 6, or imperial Diametral Pitch gears.
45# steel has a typical tensile strength of approximately 600–700 MPa and yield strength of around 355 MPa, making it well-suited for moderate-to-heavy continuous-duty drives. For very high-shock or high-cycle applications, consider whether a hardened or alloy steel variant would better suit your load profile.
45# carbon steel has limited inherent corrosion resistance. For indoor, dry environments this is generally acceptable with periodic lubrication. For humid, outdoor, or washdown environments, apply a suitable gear lubricant or consider a stainless steel or coated alternative to prevent surface oxidation.
Bore diameter varies by variant — please refer to the variant specifications or contact us to confirm the bore size for your selected tooth count. The steel is machinable, so the bore can be enlarged or a keyway added by a competent machine shop if the standard bore does not match your shaft.
Yes. These Module 5 spur gears are a direct match for standard Mod 5 steel or nylon racks used in CNC gantry and linear motion systems. Ensure your rack is also Module 5 with a 20° pressure angle. The 40 mm face width provides ample contact area for the thrust loads typical in CNC router X/Y axes.
Apply a suitable open-gear grease or EP (extreme pressure) gear oil to the tooth flanks during installation and re-lubricate at regular service intervals based on your duty cycle. Inspect teeth periodically for pitting, wear, or chipping. Clean away old lubricant and debris before re-applying fresh grease.
