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When your CNC machine, conveyor, or robotic arm demands consistent torque transfer without slippage or premature wear, the right spur gear makes all the difference. Engineers, makers, and maintenance professionals who need a dependable 2 Mod spur gear with a broad tooth-count selection will find this C45 steel transmission gear built to perform across demanding duty cycles.
Each gear is machined from C45 medium-carbon steel — a material known for its balanced hardness and machinability — and features a straight-tooth (spur) profile with a 2 mm module. Tooth counts span 25T through 35T (25, 26, 27, 28, 30, 32, 34, 35 teeth), with bore diameters ranging from 8 mm (~0.31 in) to 30 mm (~1.18 in). Most bore variants include a precision-cut keyway (4 mm, 5 mm, or 8 mm) for positive shaft engagement; select sizes are also available with a rough bore for custom machining.
Typical applications include light-to-medium industrial gearboxes requiring a 2 Mod spur gear for speed reduction, DIY CNC router Z-axis drive assemblies using a 25T–30T transmission gear, and robotics joint actuators where a compact C45 steel spur gear with keyway ensures repeatable positioning accuracy.
| Module | 2 (Mod 2) |
|---|---|
| Tooth Count | 25T, 26T, 27T, 28T, 30T, 32T, 34T, 35T |
| Material | C45 Medium-Carbon Steel |
| Gear Type | Straight Spur Gear |
| Pressure Angle | 20° (standard) |
| Bore Diameter Range | 8 mm – 30 mm (0.31 in – 1.18 in) |
| Keyway Width Options | 4 mm, 5 mm, 8 mm (see variant options) |
| Bore Type | Finished bore with keyway, or rough bore (see variant options) |
| Pitch Diameter Range | 50 mm (25T) – 70 mm (35T) |
| Surface Finish | See variant options |
| Weight | See variant options |
Select your tooth count based on the gear ratio you need. Divide the driven gear teeth by the driving gear teeth to get the ratio. For example, pairing a 25T driving gear with a 50T driven gear gives a 2:1 speed reduction. Use a higher tooth count (e.g., 34T or 35T) when you need a larger pitch diameter or smoother load distribution at lower speeds.
Measure your shaft diameter precisely with a micrometer or caliper. Choose the bore size that matches your shaft — the bore should be a close sliding or light interference fit. If your shaft diameter falls between listed bore sizes, select the rough-bore option (available on 32T, 34T, and 35T) and machine the bore to your exact specification.
A keyway is a slot cut into the bore that accepts a key (a small rectangular block) to lock the gear to the shaft and prevent rotational slipping under torque. The correct keyway width is determined by your shaft diameter: 4 mm keyways suit smaller bores (12 mm), 5 mm keyways suit mid-range bores (14–16 mm), and 8 mm keyways suit larger bores (24–30 mm). Always match the keyway width to the key specified for your shaft size per DIN 6885 or equivalent standard.
C45 steel (equivalent to AISI 1045) has a typical tensile strength of approximately 600–800 MPa in the normalized condition, making it well-suited for light-to-medium industrial drives, robotics, and DIY machinery. For very high-torque or shock-load applications, consider whether a heat-treated or alloy-steel gear would be more appropriate for your duty cycle.
C45 carbon steel is not inherently corrosion-resistant. In humid or wet environments, apply a suitable lubricant (gear oil or grease) and consider a protective coating or periodic re-lubrication schedule. For environments with direct water exposure, a stainless steel or coated gear may be a better long-term choice.
Yes — any gear marked Module 2 (Mod 2) will mesh correctly with another Mod 2 gear of the same pressure angle (20°). Confirm the pressure angle of your existing gearbox gears before ordering. These gears follow the standard 20° pressure angle profile used in the vast majority of industrial and hobbyist Mod 2 drivetrains.
Yes. The 25T–30T variants with smaller bores (8–12 mm) are commonly used in CNC router axis drives and extruder gearboxes where a compact 2 Mod spur gear with keyway provides reliable, backlash-controlled motion. Ensure your motor shaft diameter matches the selected bore and that the gear ratio suits your steps-per-mm or feed-rate requirements.
