Straight Spur Gear 45# Steel Motor Gears 2Mod 17T 20Pcs and 1Mod 20T 20Pcs

Module size determines which gears can mesh together — a 2Mod gear can only mesh with another 2Mod gear, and a 1Mod gear only with 1Mod. Choose based on the module of the mating gear already in your drivetrain. The 2Mod 17T is suited for higher-torque, lower-speed stages; the 1Mod 20T fits compact, higher-speed reduction stages where space is limited.

45# medium-carbon steel has a typical tensile strength of approximately 600–800 MPa in the normalized condition, making it suitable for moderate-load motor drive applications such as robotics joints, small CNC axes, and automation conveyors. For very high-shock or high-RPM applications, consider whether a heat-treated or alloy steel gear would better suit your load requirements.

45# steel is not inherently corrosion-resistant. In humid or outdoor environments, we recommend applying a light machine oil coating, using a protective enclosure, or selecting a variant with a surface treatment if available. For environments with direct water exposure, stainless steel or plastic gears may be more appropriate.

Bore diameter compatibility depends on the specific variant you select. Common bore sizes for this type of gear range from 4 mm to 12 mm. Check the variant options above for available bore diameters and match them to your motor shaft diameter. If your shaft requires a keyway or set-screw flat, verify that the selected variant includes it or that the bore can be machined to your spec.

The 2Mod and 1Mod gears cannot mesh directly with each other — they must be used in separate stages. However, both can be incorporated into a multi-stage gearbox where each stage uses its own matching module pair. This combo pack is designed for builders who need both module sizes for different stages of the same assembly.

For standard spur gears, center distance = (T1 + T2) × Module / 2. For two 2Mod gears where one is 17T and the mating gear is N teeth: center distance = (17 + N) × 2 / 2 mm. For 1Mod gears: center distance = (20 + N) × 1 / 2 mm. This formula assumes standard (non-profile-shifted) gears with a 20° pressure angle.

The most common methods are a set screw through the hub (if the variant includes a tapped hole), a press fit for tight-tolerance bores, or a shaft key and keyway. Check the variant description for hub features. For prototyping, a set-screw hub is the most convenient; for production, a keyed or interference-fit bore provides more reliable torque transmission.