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When your motion-transmission project demands a reliable 90° direction change without backlash headaches, finding a straight bevel gear that matches your exact shaft diameter and tooth count can be frustrating. Whether you're a mechanical engineer prototyping a gearbox, a robotics hobbyist building a drive train, or a maker upgrading CNC or automation equipment, these straight bevel gears give you the dimensional precision you need right out of the box.
Each gear is machined from 45# medium-carbon steel, offering a solid balance of strength and machinability. The range covers module 1, 1.5, and 2 (Mod 1 / Mod 1.5 / Mod 2), with tooth counts of 20T, 25T, and 30T (plus 16T in Mod 1.5), and bore diameters spanning 5 mm to 30 mm (approx. 0.20" to 1.18"). Keyed-bore variants include standard key slots of 3 mm, 4 mm, 5 mm, and 6 mm to suit common shaft keyway standards. Outer diameters range typically from 22 mm to 64 mm (approx. 0.87" to 2.52") depending on module and tooth count.
These straight bevel gears are well-suited for 1:1 ratio 90° power transmission in DIY gearboxes and speed reducers, shaft-to-shaft direction-change drives in 3D printers and CNC routers, and light-to-medium industrial automation assemblies requiring matched bevel gear pairs.
Machined from 45# medium-carbon steel for reliable strength, wear resistance, and long service life in mechanical drive applications.
Available in Mod 1, Mod 1.5, and Mod 2 with 16T, 20T, 25T, and 30T options — covering a broad range of torque and speed requirements.
Plain bore variants from 5 mm to 16 mm and keyed bore variants from 8 mm to 30 mm let you match your exact shaft specification without custom machining.
Choose plain bore for press-fit or set-screw mounting, or select keyed variants (Key3 / Key4 / Key5 / Key6) for positive torque transmission on keyed shafts.
Matched pairs deliver a precise 1:1 ratio for 90° shaft-to-shaft power transfer — ideal for direction-change drives in robotics, automation, and DIY machinery.
Fits standard metric shaft and keyway dimensions, making these gears compatible with common stepper motors, servo shafts, and industrial drive components.
| Material | 45# Medium-Carbon Steel |
|---|---|
| Gear Type | Straight Bevel Gear |
| Transmission Ratio | 1:1 |
| Module (Mod) | 1 / 1.5 / 2 |
| Tooth Count | 16T / 20T / 25T / 30T (varies by module) |
| Bore Diameter | 5 mm – 30 mm (0.20" – 1.18") — See variant options |
| Key Slot Width | 3 mm / 4 mm / 5 mm / 6 mm (keyed variants only) |
| Outer Diameter (approx.) | See variant options |
| Pressure Angle | 20° (standard metric) |
| Surface Finish | See variant options |
| Weight | See variant options |
The module (Mod) determines the gear tooth size and pitch — a higher module means larger, stronger teeth suited for higher torque. For light-duty robotics or small mechanisms, Mod 1 is typically sufficient. Mod 1.5 suits medium-load drives, while Mod 2 handles heavier torque requirements. The tooth count (20T, 25T, 30T) affects the gear's outer diameter; for a 1:1 ratio, both mating gears must share the same module and tooth count.
Select a bore diameter that matches your shaft's outer diameter exactly. For plain bore variants, the gear is typically secured with a set screw or press fit. For keyed variants, ensure your shaft has a matching keyway — the key width must match the listed key slot (Key3 = 3 mm key, Key4 = 4 mm key, Key5 = 5 mm key, Key6 = 6 mm key). If your shaft is between sizes, choose the smaller bore and have it reamed to fit.
45# steel offers good tensile strength (typically 600–800 MPa) and is widely used in mechanical transmission components. These gears are suitable for light-to-medium duty applications such as CNC routers, 3D printers, robotics, and small automation assemblies. For continuous heavy-load or high-speed industrial use, consider whether additional heat treatment or a higher-alloy steel would be appropriate for your specific load conditions.
45# carbon steel has moderate corrosion resistance. For indoor or dry environments, the gears perform well without additional treatment. If used in humid, outdoor, or mildly corrosive environments, applying a light machine oil or grease coating is recommended to prevent surface oxidation. For highly corrosive environments, consider stainless steel alternatives.
Yes. A bevel gear drive requires two mating gears. For a 1:1 ratio, both gears must have the same module and the same tooth count. Select two units of the same variant (e.g., two 1.5Mod 20T gears with your required bore sizes) to form a complete 90° transmission pair. The bore sizes of the two gears can differ to match different shaft diameters on each axis.
Plain bore variants have a smooth cylindrical bore and are typically secured to the shaft using a set screw or interference fit. They are easier to install and remove. Keyed bore variants include a machined keyway slot that accepts a standard key, providing a positive mechanical connection that prevents the gear from rotating on the shaft under load — making them the preferred choice for higher-torque or reversing-load applications.
These gears are dimensioned in metric (mm). While some bore sizes may be close to common imperial shaft diameters (e.g., 8 mm ≈ 5/16", 10 mm ≈ 3/8", 12 mm ≈ 15/32"), metric and imperial dimensions are not interchangeable without machining. We recommend verifying your shaft's exact diameter in millimeters before selecting a bore size, or having the bore reamed to your required dimension by a local machine shop.
