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When a slipping or undersized gear brings your CNC router, conveyor, or automation rig to a halt, you need a replacement you can trust to hold torque without play. These Mod 5 spur gears are machined for engineers, makers, and industrial maintenance teams who demand dimensional accuracy and consistent mesh quality across every tooth count.
Each gear is machined from 45# medium-carbon steel, delivering a solid balance of hardness and machinability. The tooth profile follows the standard Module 5 (Mod 5) specification with a 20° pressure angle. Face width (thickness) is 40 mm (approx. 1.57 in), and the available tooth counts run from 10T through 29T — covering pitch circle diameters from approximately 50 mm (1.97 in) up to 145 mm (5.71 in).
Typical applications include CNC machine spindle drives requiring mod 5 pinion gears, robotic arm joint transmission assemblies, and industrial conveyor reduction stages where a steel spur gear with 40mm face width provides the load capacity needed for continuous-duty cycles.
Machined from 45# steel for a tensile strength typically in the 600–800 MPa range, giving these pinion gears the toughness to handle sustained radial and tangential loads without deforming under shock.
Tooth geometry conforms to the ISO/DIN Module 5 standard with a 20° pressure angle, ensuring smooth, low-noise mesh with any compatible Mod 5 mating gear or rack in your drivetrain.
A 40 mm (1.57 in) tooth face width distributes contact stress across a wide surface, reducing wear rate and extending service life compared to narrower gears in the same module class.
Twenty discrete tooth counts let you dial in the exact gear ratio your transmission requires — from compact 10-tooth pinions for high-speed stages to 29-tooth gears for torque-multiplying reduction steps.
Each gear is turned and hobbed to consistent tolerances, with a machined center bore ready for shaft fitting. Keyway and set-screw options vary by tooth count — see variant options for details.
The standardized Mod 5 pitch makes these gears interchangeable with existing Mod 5 components in CNC routers, robotic joints, and conveyor reduction stages, minimizing downtime during replacement or upgrades.
| Module | Mod 5 (M5) |
|---|---|
| Pressure Angle | 20° |
| Material | 45# Medium-Carbon Steel |
| Face Width (Thickness) | 40 mm (1.57 in) |
| Tooth Count Range | 10T – 29T (select variant) |
| Pitch Circle Diameter Range | 50 mm – 145 mm (approx. 1.97 in – 5.71 in) |
| Tooth Profile Standard | ISO/DIN Module 5 |
| Bore Diameter | See variant options |
| Keyway | See variant options |
| Surface Finish | See variant options |
| Gear Type | External Spur Gear (Pinion) |
| Quantity per Order | 1 Pcs |
The tooth count determines your gear ratio. Divide the tooth count of the driven gear by the tooth count of the driving pinion to get the ratio. For example, pairing a 10T pinion with a 20T gear gives a 2:1 reduction. Choose a smaller tooth count for higher speed output and a larger tooth count for more torque. If you are replacing an existing gear, match the tooth count exactly to maintain your original ratio.
45# medium-carbon steel typically achieves a tensile strength of approximately 600–800 MPa in the normalized or quenched-and-tempered condition. For most CNC, robotics, and light-to-medium industrial conveyor applications, this is more than adequate. If your application involves very high shock loads or continuous heavy-duty cycling, consider whether a hardened or alloy-steel gear would better suit your requirements.
45# carbon steel has limited inherent corrosion resistance. For indoor, dry, or lightly oiled environments these gears perform well with standard lubrication. If your application involves moisture, chemicals, or outdoor exposure, we recommend applying a rust-inhibiting grease or oil regularly, or contacting us to discuss alternative material options.
Yes — as long as your existing rack or mating gear is also Module 5 with a 20° pressure angle, these gears will mesh correctly. Module (pitch) and pressure angle must match between mating gears. If you are unsure of your existing gear's module, you can measure the pitch circle diameter and divide by the tooth count; the result should equal 5 mm for a Mod 5 gear.
Bore diameter varies by tooth count and hub size. Please refer to the variant options on this page or contact us with your shaft diameter before ordering so we can confirm the correct fit. We can also advise on keyway dimensions if your shaft requires a keyed connection.
Spur gears transmit torque through radial tooth forces and do not generate axial thrust, making them suitable for both horizontal and vertical shaft orientations. For overhung shaft configurations, ensure your bearing arrangement is rated for the resulting radial load at the gear mesh point. The 40 mm face width helps distribute load, but proper shaft and bearing sizing remains essential for reliable operation.
These gears are sold individually (1 Pcs per order) and are designed as direct replacements for any worn or damaged Mod 5 pinion in your existing drivetrain. If you need a complete gear pair or a mating gear of a different tooth count, simply add the required variants to your cart separately. Contact us if you need help selecting a matched pair for a specific ratio.
