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When a mismatched or undersized gear causes backlash, premature wear, or unexpected downtime on your CNC router, 3D printer frame, or industrial drive train, the fix starts with selecting the right module 4 spur gear. These module 4 spur gears are engineered for makers, machine builders, and automation engineers who need dimensionally accurate, drop-in replacements or new-build drive components without compromise.
Each gear is machined from 45# medium-carbon steel — a material known for its balanced hardness and toughness — and features a 40 mm (approximately 1.57 in) face width. The tooth count range spans 12 T through 48 T, with pitch diameter scaling from approximately 48 mm (1.89 in) for the 12-tooth variant up to approximately 192 mm (7.56 in) for the 48-tooth variant. Bore diameter and keyway dimensions vary by tooth count; see variant options for confirmed bore specs.
Typical use cases include rack-and-pinion linear motion systems for CNC gantry axes, gear-reduction stages in 3D printer extruder drives, and rotary indexing tables in light industrial automation — all applications where a module 4 spur gear with a 40 mm face width delivers the torque capacity and positional accuracy the job demands.
| Module (Mod) | 4 |
|---|---|
| Tooth Count Range | 12 T – 48 T (see variant options) |
| Face Width | 40 mm (≈ 1.57 in) |
| Material | 45# Medium-Carbon Steel |
| Tooth Profile | Involute, 20° pressure angle |
| Pitch Diameter | Module × Teeth (e.g., 4 × 20 = 80 mm) |
| Bore Diameter | See variant options |
| Keyway | See variant options |
| Surface Finish | See variant options |
| Quantity per Order | 1 Pcs (default); bulk options available |
Calculate your required gear ratio first: divide the driver tooth count by the driven tooth count. For a CNC gantry axis, match the pinion tooth count to your rack pitch and motor torque spec. A lower tooth count (12–20 T) gives a smaller pitch diameter and higher rotational speed; a higher tooth count (30–48 T) increases pitch diameter and torque multiplication. Use the formula: Pitch Diameter = Module × Teeth (e.g., 4 × 20 = 80 mm).
45# steel has a typical tensile strength of approximately 600–800 MPa depending on heat treatment. The 40 mm face width distributes tooth load effectively for moderate-to-high torque applications. Exact load ratings depend on operating speed, lubrication, and duty cycle. For heavy continuous-duty industrial use, consult a mechanical engineer to verify the safety factor for your specific application.
45# carbon steel offers moderate corrosion resistance. For environments with moisture, coolant exposure, or outdoor use, we recommend applying a light machine oil or grease coating during operation, or specifying a surface-treated variant. If corrosion resistance is a primary requirement, consider stainless steel or nylon gears for your application.
Yes — any gear or rack manufactured to the Module 4 (Mod 4) standard with a 20° pressure angle will mesh correctly with these gears. Verify that the mating component is also Module 4; mixing modules (e.g., Mod 3 with Mod 4) will result in incorrect mesh and accelerated wear.
Bore diameter and keyway dimensions vary by tooth count to maintain appropriate hub wall thickness. Please refer to the variant detail page or contact us to confirm the exact bore and keyway dimensions for your selected tooth count before ordering, especially if you are fitting the gear to a specific shaft diameter.
Module 4 gears are on the larger end of the spectrum for desktop 3D printer extruders, which more commonly use Mod 0.5–1 gears. However, for large-format 3D printers, industrial FDM machines, or custom extruder gear-reduction stages where a Mod 4 gear is specified, these are a direct fit. Confirm your extruder's gear module before ordering.
Yes, lubrication is recommended for all steel spur gear applications. Apply a suitable gear grease or machine oil to the tooth flanks during initial installation and re-lubricate at regular maintenance intervals. Proper lubrication reduces tooth wear, lowers operating temperature, and significantly extends gear service life.
