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When your drivetrain demands a precise 90° direction change without sacrificing torque or smoothness, mismatched or single-handed bevel gears create vibration, noise, and premature wear. These 1:1 spiral bevel gear sets are sold as matched pairs — one left-hand and one right-hand spiral — engineered to mesh together from the factory for balanced load distribution and quiet operation. Ideal for makers, machine builders, and mechanical engineers who need reliable right-angle power transmission in compact assemblies.
Each pair consists of two spiral bevel gears machined from 45# medium-carbon steel, heat-treated for surface hardness and core toughness. Available in five modulus options (1, 1.5, 2, 2.5, and 3 Mod) and three tooth counts (20, 25, and 30 teeth), with bore diameters ranging from 6 mm (approx. 0.24 in) up to 25 mm (approx. 0.98 in). Keyway options are available on larger bore sizes (4 mm, 5 mm, 6 mm, and 8 mm keyways depending on bore), and a process-hole variant is offered for custom boring to your exact shaft size.
Typical use cases include CNC router axis drives requiring right-angle gearbox assemblies, custom robotic joint mechanisms needing compact 1:1 bevel gear transmission, and industrial automation equipment where a spiral bevel gear pair replaces worn straight-cut bevel sets for quieter, higher-load operation.
| Gear Type | Spiral Bevel Gear (Left-Right Matched Pair) |
|---|---|
| Gear Ratio | 1:1 |
| Shaft Angle | 90° |
| Material | 45# Medium-Carbon Steel |
| Surface Treatment | Heat-treated (surface hardened) |
| Available Modulus | 1 Mod / 1.5 Mod / 2 Mod / 2.5 Mod / 3 Mod |
| Number of Teeth | 20T / 25T / 30T |
| Bore Diameter Range | 6 mm – 25 mm (approx. 0.24 in – 0.98 in) |
| Keyway Options | 4 mm / 5 mm / 6 mm / 8 mm (bore-dependent; see variant options) |
| Packing Quantity | 1 Pair (1 left-hand + 1 right-hand gear) |
| Pressure Angle | See variant options |
| Weight | See variant options |
Modulus (Mod) determines the size of each tooth — a higher modulus means larger, stronger teeth capable of transmitting more torque. For light-duty or compact assemblies (small motors, hobby CNC), 1–1.5 Mod is typically sufficient. For medium-load industrial or robotic applications, 2–3 Mod is recommended. Tooth count affects the pitch circle diameter: 20T gives the smallest gear body, while 30T gives a larger diameter with more tooth contact area. Match your modulus to your torque requirement and your tooth count to your available space envelope.
Select a bore diameter that matches your shaft diameter exactly. Plain bore options (6, 8, 10, 12 mm) are suitable for shafts secured with set screws or adhesive. Keyed bore options (10–25 mm with 4–8 mm keyways) are recommended for higher-torque applications where positive rotational locking is required. If your shaft diameter falls between standard sizes or requires a custom fit, select the Process Hole variant — the gear is supplied with a pilot hole for you to bore or ream to your exact specification.
Each listing is sold as a matched pair: 1 left-hand spiral gear + 1 right-hand spiral gear of the same modulus and tooth count. Left and right spiral bevel gears must be used together — a left-hand gear cannot mesh correctly with another left-hand gear. Purchasing as a pre-matched pair ensures correct helix direction compatibility and eliminates the guesswork of sourcing matching halves separately.
These gears are machined from 45# medium-carbon steel with surface hardening, giving tooth flanks good wear resistance while maintaining a tough core to resist shock loads. Exact load ratings depend on modulus, tooth count, operating speed, and lubrication conditions. As a general guide, larger modulus (2.5–3 Mod) and higher tooth counts (30T) provide greater load capacity. For precise torque ratings in your specific application, consult a mechanical engineer or contact us to confirm suitability.
45# steel has moderate corrosion resistance. In dry or lightly humid indoor environments, the heat-treated surface provides adequate protection under normal operating conditions. For wet, outdoor, or chemically exposed environments, we recommend applying a suitable gear lubricant or grease to the tooth flanks and considering a protective coating or housing enclosure. If corrosion resistance is a primary requirement, contact us to discuss alternative material options.
Straight bevel gears have teeth that are cut straight along the tooth face, causing all tooth contact to occur simultaneously — this produces more noise and vibration, especially at higher speeds. Spiral bevel gears have curved, helical teeth that engage gradually along the tooth length, distributing load more evenly across the tooth face. This results in quieter operation, smoother torque transfer, higher load capacity for a given gear size, and longer service life. Spiral bevel gears are the preferred choice for continuous-duty or higher-speed right-angle drives.
Operating bevel gears without lubrication significantly accelerates tooth wear and can lead to premature failure, especially under load or at elevated speeds. We recommend applying a suitable gear grease or oil to the tooth mesh area before initial operation and maintaining lubrication at regular service intervals. For enclosed gearbox applications, an appropriate gear oil fill level should be maintained. Dry running is only acceptable for very light loads at low speeds and short duty cycles.
