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When a gear fails mid-project or simply doesn't exist in the right size, the entire build stalls. Whether you're a hobbyist assembling a custom gearbox, a maker building a CNC router, or a technician replacing worn drive components, finding a reliable 2M module spur gear in the exact tooth count you need shouldn't be a challenge. These 2M cylindrical spur gears are stocked across a wide size range specifically for builders who need the right part, right now.
Each gear is machined from 45# carbon steel — a medium-carbon structural steel known for its balanced hardness and machinability. The module is 2M (2mm per tooth pitch), with tooth counts ranging from 12T to 100T and corresponding outer diameters from 28mm (1.10 in) to 204mm (8.03 in). The bore diameter and face width vary by size; see variant options for exact bore dimensions. Available individually or in packs of 5 or 10 for multi-gear assemblies.
Typical use cases include DIY gearbox and speed reducer assemblies, 3D printer and CNC axis drive trains, robotic arm joint mechanisms requiring precise gear ratios, and replacement gearing in light industrial or agricultural equipment. The standardized 2M module ensures compatibility with any mating 2M rack, pinion, or gear in your drivetrain.
45# Carbon Steel Construction — Medium-carbon steel provides a reliable balance of tensile strength and machinability, suitable for moderate-load power transmission applications in DIY and light industrial use.
Wide Size Range: 12T to 100T — Covers outer diameters from 28mm (1.10 in) up to 204mm (8.03 in), giving you the flexibility to match exact gear ratio requirements without custom machining.
Standardized 2M Module — The 2mm module pitch is a globally recognized standard, ensuring direct interchangeability with any 2M-rated mating gear, rack, or pinion in your drivetrain.
Cylindrical Spur Tooth Profile — Straight-cut spur teeth deliver efficient, low-noise power transfer on parallel shafts, making these gears well-suited for gearboxes, conveyors, and axis drives.
Flexible Pack Quantities — Available as single pieces, 5-packs, or 10-packs, so you can stock up for multi-stage gear trains or replacement inventory without overpaying for parts you don't need.
Machined Bore Ready for Keying — The center bore is machined to a consistent diameter per size variant, ready for shaft fitting or further keyway machining to suit your specific assembly requirements.
| Module | 2M (2mm) |
|---|---|
| Tooth Count Range | 12T – 100T |
| Outer Diameter Range | 28mm – 204mm (1.10 in – 8.03 in) |
| Material | 45# Carbon Steel |
| Gear Type | Cylindrical Spur Gear |
| Pressure Angle | 20° (standard) |
| Bore Diameter | See variant options |
| Face Width | See variant options |
| Surface Finish | See variant options |
| Packing Quantity | 1 pcs / 5 pcs / 10 pcs |
The tooth count determines your gear ratio. Divide the tooth count of the driven gear by the tooth count of the driving gear to get the ratio. For example, a 40T gear driven by a 20T gear gives a 2:1 reduction. Match the module (2M) on both gears — tooth count only affects ratio and outer diameter, not whether the gears will mesh.
Module (M) is the standardized unit of gear tooth size. A 2M module means each tooth occupies 2mm of pitch diameter per tooth. Two gears will mesh correctly only if they share the same module and pressure angle. These gears are 2M / 20° pressure angle — confirm your existing gears match both values before ordering.
45# carbon steel has a typical tensile strength of approximately 600–700 MPa and yield strength around 355 MPa in the normalized condition. These gears are suited for moderate-load applications such as DIY gearboxes, CNC drives, and light machinery. For heavy industrial or high-shock loads, consider hardened or alloy steel gears and consult a mechanical engineer for load calculations.
45# carbon steel has limited inherent corrosion resistance. For indoor or dry environments, the bare steel finish is generally adequate with periodic light lubrication. For outdoor, humid, or chemically exposed environments, we recommend applying a rust-inhibiting grease or considering a surface treatment such as zinc plating or black oxide after purchase.
Yes. The machined bore is a starting point and can be enlarged or keyway-cut by a machinist to match your shaft. Ensure the remaining wall thickness after boring is sufficient for your torque requirements. Contact us to confirm the as-supplied bore diameter for your selected size before machining.
All three packing options contain identical gears of the same size and specification. The 5-pack and 10-pack options offer a lower per-unit cost and are ideal when building multi-stage gear trains, stocking spares, or assembling multiple identical machines. Select the quantity that matches your project needs using the Packing Quantity option above.
For a 2M spur gear, the pitch diameter = Module × Tooth Count = 2 × T mm. The outer diameter (addendum diameter) = (T + 2) × 2 mm. For example, a 20T gear has an outer diameter of (20 + 2) × 2 = 44mm, which matches the listed variant. Use this formula to verify the size you need before ordering.
