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When your drivetrain demands a clean 90° direction change without sacrificing torque or smoothness, standard spur gears simply fall short. Engineers, robotics builders, and CNC hobbyists working on compact drive systems need a bevel gear set they can trust to mesh accurately and run quietly under load. These 3 mod spiral bevel gear pairs are designed for exactly that — delivering reliable right-angle power transmission in a compact, machined package.
Each set consists of a matched 1:1 ratio bevel gear pair machined from 45# medium-carbon steel, heat-treated for surface hardness and wear resistance. The spiral (twill) tooth profile spans a tooth count range of 15T through 40T, with outer diameters from approximately 48.7 mm (1.92 in) up to 123.7 mm (4.87 in). Module (mod) is 3, and the meshing angle is a precise 90°. Both gears in each pair are cut as a matched set to ensure consistent backlash and tooth contact.
Typical applications include right-angle gearbox assemblies for DIY CNC routers, custom robotic joint drives requiring a 90° bevel gear transmission, small-scale industrial automation rigs, and maker projects where a compact spiral bevel gear set replaces bulky worm gear arrangements. The spiral tooth form also makes these a strong candidate for low-noise 3 mod bevel gear replacements in existing machinery.
| Module (Mod) | 3 |
|---|---|
| Tooth Count Range | 15T – 40T (see variant options) |
| Outer Diameter Range | 48.7 mm – 123.7 mm (1.92 in – 4.87 in) |
| Meshing Angle | 90° |
| Gear Ratio | 1:1 |
| Tooth Profile | Spiral (Twill / Helical Bevel) |
| Material | 45# Medium-Carbon Steel |
| Surface Treatment | See variant options |
| Bore Diameter | See variant options |
| Hub Length | See variant options |
| Face Width | See variant options |
| Quantity per Order | 1 pc or 2 pcs (matched pair) |
Since all variants are 1:1 ratio pairs, the tooth count primarily determines the outer diameter and the physical size of the gear set. Choose a larger tooth count (e.g., 30T–40T) when you need a larger gear envelope or higher torque capacity, and a smaller count (e.g., 15T–20T) for compact installations. Confirm the outer diameter fits your housing before ordering.
You can choose either option. Selecting "1 pcs" gives you a single gear (driver or driven — both are identical in a 1:1 set). Selecting "2 pcs" gives you a complete matched bevel gear pair ready to install as a right-angle drive set.
The bore diameter varies by tooth count and is not pre-machined to a specific shaft size in most variants — it typically requires finish boring or reaming to your shaft diameter. Please contact us to confirm the as-supplied bore condition for your selected size before ordering if a specific bore is critical.
These gears are machined from 45# medium-carbon steel, which offers good tensile strength and responds well to heat treatment for surface hardness. Exact torque ratings depend on tooth count, operating speed, lubrication, and housing support. For precise load calculations, apply standard AGMA or ISO bevel gear rating methods using the module and face width of your selected variant.
45# steel is not inherently corrosion-resistant. For applications in humid or wet environments, we recommend applying a suitable gear lubricant or grease, and considering a protective coating after installation. If corrosion resistance is a primary requirement, contact us to discuss alternative material options.
These gears are manufactured to Module 3 (Mod 3) standards with a 90° meshing angle. They are designed to mesh with other Mod 3 spiral bevel gears of the same tooth count at 90°. They will not mesh correctly with different module sizes (e.g., Mod 2 or Mod 4) or with straight-cut bevel gears of a different tooth profile geometry.
Spiral (twill) bevel gears engage teeth gradually along the helical tooth line, spreading load across multiple teeth at once. This results in quieter operation, smoother torque transfer, and longer service life under continuous or higher-speed duty compared to straight-cut bevel gears, which engage the full tooth face simultaneously and can generate more noise and impact loading.
