2 Mod 12-24 Teeth Straight Spur Gear 45# Steel Motor Transmission Gear

The tooth count determines your gear ratio. Divide the driven gear's tooth count by the driving gear's tooth count to get the ratio. For example, pairing a 12T drive gear with a 24T driven gear gives a 2:1 reduction — halving speed and doubling torque. Choose a smaller tooth count (12T–16T) for higher reduction stages and larger counts (20T–24T) for lower-ratio, higher-speed stages.

Yes. All gears in this listing are machined to the Module 2 (2 Mod) metric standard with a 20° pressure angle, which is the most common metric gear standard. They will mesh correctly with any other M2 spur gear, rack, or pinion that also uses a 20° pressure angle. Always confirm the module and pressure angle of your mating component before ordering.

Measure your shaft's outer diameter — this must match the bore diameter of the gear. If your shaft uses a key for positive torque locking, also check the key width: 4 mm keys suit smaller shafts (typically 12–14 mm), 5 mm keys suit 14–18 mm shafts, 6 mm keys suit 18–22 mm shafts, and 8 mm keys suit 22–25 mm shafts. If your shaft has no keyway, select a plain bore variant and use a set screw or press fit.

45# medium-carbon steel offers a tensile strength of approximately 600–800 MPa in the normalized condition, making these gears suitable for moderate-load, moderate-speed transmission applications — typical of CNC axis drives, conveyor stages, and small motor test rigs. For very high-speed or heavy-shock-load applications, consider heat-treated or alloy-steel alternatives. Actual load capacity depends on tooth count, face width, speed, and lubrication conditions.

45# carbon steel is not inherently corrosion-resistant. For outdoor, humid, or washdown environments, apply a suitable gear lubricant or anti-rust coating after installation, or consider stainless steel or nylon gear alternatives. For standard indoor workshop and machine enclosure use, periodic lubrication is sufficient to prevent surface oxidation.

Yes. Module 2 steel spur gears are commonly used in CNC router axis gearboxes, extruder drives, and custom motion stages. Select the tooth count that achieves your target steps-per-mm or gear ratio, and ensure the bore matches your motor or idler shaft. For 3D printer extruder applications specifically, verify the face width and bore fit your chosen motor shaft before ordering.

Plain bore variants have a smooth cylindrical bore and are typically secured to a shaft using a set screw, interference fit, or adhesive. Keyway (KWY) variants have a machined slot in the bore that accepts a standard parallel key, providing a positive mechanical lock that prevents rotational slipping under torque. Keyway variants are recommended for applications with reversing loads or high torque, where a set screw alone may not be sufficient.