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When a slipping or undersized gear stalls your build mid-project, every minute of downtime costs you. Makers, engineers, and CNC hobbyists who demand consistent torque transfer and dimensional accuracy need a gear they can trust across hundreds of operating hours. These Module 3 spur gears are machined from 45# medium-carbon steel to deliver the rigidity and wear resistance that plastic or low-grade metal alternatives simply cannot match.
Each gear features a Module 3 tooth profile with a 30 mm (1.18 in) face width, available in 10 through 36 teeth. The bore and keyway dimensions vary by tooth count — refer to variant options for exact bore specifications. The 45# steel construction provides a tensile strength typically in the range of 600–800 MPa, making these gears well-suited for moderate-to-high load applications without the bulk of cast-iron alternatives.
Typical use cases include: direct-drive extruder upgrades on FDM 3D printers requiring precise filament feed ratios; Z-axis and gantry drive systems on CNC routers and laser engravers where backlash must be minimized; and custom robotics or automation rigs where a compact, steel-bodied spur gear replaces a worn nylon or POM component. Long-tail applications also include DIY lathe gear trains, motorized camera sliders, and educational STEM mechanism kits.
Machined from 45# steel for a balance of hardness and machinability, delivering durability under sustained rotational loads without brittleness.
Standard Mod 3 geometry ensures direct interchangeability with any Mod 3 rack or mating gear — no custom tooling or adapters required.
A 30 mm (1.18 in) thick gear body distributes torque across a wider contact area, reducing tooth stress and extending service life compared to thinner alternatives.
Select from 27 variants (10T through 36T) to dial in your exact gear ratio for extruder drives, CNC axes, or custom transmission designs.
CNC-hobbed tooth flanks maintain consistent pitch and pressure angle, minimizing positional error in motion-critical applications like 3D printer axes and robotic joints.
Suitable for 3D printer extruders, CNC router drives, laser engraver gantries, robotics, and DIY automation — wherever a compact steel spur gear is needed.
| Module | 3 (Mod 3) |
|---|---|
| Material | 45# Medium-Carbon Steel |
| Face Width (Thickness) | 30 mm (1.18 in) |
| Tooth Count Range | 10 – 36 Teeth |
| Pressure Angle | 20° |
| Pitch Diameter | 30 mm (10T) – 108 mm (36T) |
| Bore Diameter | See variant options |
| Keyway | See variant options |
| Surface Finish | Natural steel (uncoated) |
| Tooth Form | Involute spur |
| Compatible Gear Type | Mod 3 spur gears, racks, pinions |
| Typical Application | 3D printers, CNC routers, robotics, automation |
Your gear ratio is determined by dividing the tooth count of the driven gear by the tooth count of the driving gear. For example, pairing a 10-tooth pinion with a 30-tooth gear gives a 3:1 reduction. Calculate your required ratio first, then select the tooth counts that achieve it while fitting within your available space envelope. The pitch diameter equals Module × Tooth Count, so a 3 Mod 20-tooth gear has a 60 mm pitch diameter.
45# medium-carbon steel typically exhibits a tensile strength in the range of 600–800 MPa and a yield strength of approximately 355–490 MPa in the normalized or quenched-and-tempered condition. For most 3D printer, CNC router, and light robotics applications, this is more than adequate. For very high-torque or impact-loaded drives, consider whether a heat-treated or alloy steel gear would be more appropriate.
Yes — any gear or rack with a Module 3 tooth profile and a 20° pressure angle will mesh correctly with these gears. Module is a standardized metric system, so Mod 3 components from different manufacturers are interchangeable as long as the module and pressure angle match. Always verify the pressure angle (20° is standard) before mixing components.
Bore diameter varies by tooth count and is listed in the variant options on this page. Please check the specific variant detail before ordering to confirm the bore fits your shaft. If you need a custom bore size, the 45# steel material is readily machinable for secondary boring or reaming operations.
45# steel is not inherently corrosion-resistant. These gears are supplied with a natural steel finish and will oxidize if exposed to moisture without protection. For environments with humidity or occasional liquid exposure, apply a light machine oil or grease to the tooth flanks and bore. For highly corrosive environments, consider stainless steel or plastic alternatives.
Yes. Module 3 steel spur gears are commonly used in direct-drive and geared extruder designs where a precise, low-backlash gear mesh is needed to control filament feed rate. Select the tooth count that achieves your target gear ratio (typically 3:1 to 5:1 for most extruder designs), and verify the bore matches your motor shaft diameter. The 30 mm face width provides ample contact area for the torque levels typical of extruder stepper motors.
For optimal performance and longevity, apply a thin film of gear grease or machine oil to the tooth flanks before initial operation. Re-lubricate periodically based on your duty cycle — light intermittent use may only require lubrication every few months, while continuous or high-speed operation benefits from more frequent intervals. Avoid dry running, which accelerates tooth wear on steel-to-steel mesh pairs.
