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Finding a flat spur gear that matches your exact module, tooth count, and bore specification without ordering custom parts is a persistent challenge for robotics builders, CNC machine designers, and automation engineers. This range of C45 steel flat spur gears covers Module 1 (Mod 1) and Module 2 (Mod 2) in tooth counts from 12T to 160T, giving hobbyists and professional engineers a single source for the most commonly required gear sizes.
Each gear is machined from C45 medium carbon steel - a widely used engineering material offering a tensile strength of approximately 600-800 MPa in the normalized condition - and features a precision-hobbed tooth profile for consistent mesh quality. Module 1 gears have a tooth pitch of 3.14 mm (0.124 in) per tooth, while Module 2 gears have a pitch of 6.28 mm (0.247 in). Bore diameter and face width vary by tooth count; refer to variant options for exact dimensions.
Typical applications include motor pinion drives in DC gear-motor assemblies, rack-and-pinion linear actuators for CNC router Z-axes, rotary indexing tables in light manufacturing fixtures, and open-frame gear trains in educational robotics kits - all scenarios where a standardized metric module gear is required for interchangeable drivetrain design.
| Gear Type | Flat spur gear (external) |
|---|---|
| Material | C45 medium carbon steel |
| Module | Mod 1 / Mod 2 (see variant options) |
| Tooth Count | 12T - 160T (see variant options) |
| Tooth Profile | Involute, 20 degree pressure angle |
| Pitch (Mod 1) | 3.14 mm (0.124 in) per tooth |
| Pitch (Mod 2) | 6.28 mm (0.247 in) per tooth |
| Bore Diameter | See variant options |
| Face Width | See variant options |
| Surface Finish | Natural steel (uncoated) |
| Pack Quantity | 1 / 2 / 5 pcs (see variant options) |
Module (Mod) defines the size of the gear teeth. Mod 1 has smaller teeth (3.14 mm pitch) and is suited to lighter loads and compact mechanisms such as small motor pinions and robotics joints. Mod 2 has larger teeth (6.28 mm pitch) and handles higher torque loads in heavier drivetrains. Both gears of the same module must be used together - a Mod 1 gear cannot mesh with a Mod 2 gear.
Gear ratio = driven gear teeth divided by driving gear (pinion) teeth. For example, pairing a 12T pinion with a 60T driven gear gives a 5:1 reduction ratio. Select the tooth counts that achieve your target ratio while keeping the center distance within your design envelope. The center distance (in mm) = (T1 + T2) x Module / 2.
Bore diameter varies by tooth count and module. Please refer to the variant options or contact us to confirm the bore size for your specific model before ordering. Most gears in this range can be re-bored or keyed by a machine shop if the standard bore does not match your shaft diameter.
C45 steel has a normalized tensile strength of approximately 600-800 MPa, making these gears suitable for light-to-medium duty power transmission. Actual load capacity depends on tooth count, module, face width, speed, and lubrication. For heavy-duty or continuous high-speed applications, consider gears made from alloy steel or with surface hardening treatment.
C45 steel is not inherently corrosion-resistant. These gears are supplied with a natural steel finish and will oxidize if exposed to moisture without protection. For environments with humidity or occasional water exposure, apply a light machine oil or grease coating. For wet or outdoor environments, consider stainless steel or plastic gears instead.
Yes. A Mod 1 spur gear will mesh correctly with a Mod 1 rack, and a Mod 2 spur gear will mesh with a Mod 2 rack. Ensure the rack and pinion share the same module and pressure angle (20 degrees). This combination is commonly used for CNC router Z-axis drives, linear actuators, and sliding gate mechanisms.
Yes. The tooth geometry follows the standard involute profile with a 20 degree pressure angle, consistent with DIN 867 and ISO 54 metric spur gear standards. This means they are dimensionally interchangeable with other metric module spur gears of the same module and tooth count from any manufacturer following these standards.
