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When a stripped or undersized gear brings your motor drive, CNC axis, or automation project to a halt, you need a replacement that fits right and holds up under load. This 45# steel spur gear is designed for makers, engineers, and technicians who demand dimensional accuracy and consistent tooth engagement in compact transmission systems.
This spur gear is machined from 45# medium-carbon steel, offering a solid balance of hardness and machinability. It features a 1 Module (Mod 1) tooth profile with 23 teeth, giving an outer diameter of approximately 25 mm (0.98 in) and a face width typically in the 8–12 mm (0.31–0.47 in) range. Bore diameter varies by variant — see variant options for exact bore size.
Typical applications include DC motor pinion drives in robotics and automation, CNC router and 3D printer axis transmission systems, and DIY gearbox builds where a standard Mod 1 spur gear for motor shaft is required. The straight-tooth profile ensures smooth, low-noise meshing with any compatible Mod 1 rack or mating gear.
Machined from 45# steel for a dependable combination of tensile strength and wear resistance, suitable for continuous-duty motor pinion applications.
Conforms to the Mod 1 gear standard, ensuring direct interchangeability with any compatible Mod 1 rack, pinion, or mating spur gear in your drivetrain.
Straight involute teeth are cut to tight tolerances for consistent pitch-circle engagement, minimising backlash and vibration in high-cycle drive systems.
The ~25 mm OD (approx. 0.98 in) makes this gear ideal for space-constrained motor mounts, servo brackets, and compact gearbox enclosures.
Order in the pack size that suits your project — from single units for a quick repair to bulk packs for production runs or workshop stock.
Multiple bore diameter variants available to match common motor shaft sizes. Select your required bore from the variant options above before adding to cart.
| Material | 45# Medium-Carbon Steel |
|---|---|
| Module | 1 (Mod 1) |
| Number of Teeth | 23 |
| Outer Diameter | ~25 mm (~0.98 in) |
| Pitch Diameter | 23 mm (0.91 in) |
| Face Width | Typically 8–12 mm (0.31–0.47 in) |
| Bore Diameter | See variant options |
| Pressure Angle | 20° |
| Tooth Profile | Straight Involute |
| Finish | See variant options |
| Packing Quantity | See variant options |
Measure your motor shaft diameter with a caliper before ordering. The bore of the gear must match the shaft diameter exactly for a secure fit. If your shaft has a keyway, select a bored-and-keyed variant where available, or plan to machine a keyway after fitting.
Yes — any gear or rack with a Module 1 (Mod 1) tooth profile and a 20° pressure angle will mesh correctly with this gear. Confirm both the module and pressure angle of your existing components before ordering.
45# steel (equivalent to SAE 1045) has a tensile strength of approximately 600–800 MPa in its normalised state, making it well-suited for moderate-load motor pinion drives. For very high-torque or shock-load applications, consider a hardened or alloy-steel variant.
45# carbon steel has limited inherent corrosion resistance. For outdoor or humid environments, apply a light machine oil or grease to the gear teeth and bore after installation. If corrosion resistance is a primary requirement, look for a stainless steel or zinc-plated variant.
The module number defines the ratio of pitch diameter to number of teeth. A Mod 1 gear has a pitch diameter (in mm) equal to its tooth count — so a 23-tooth Mod 1 gear has a 23 mm pitch diameter. Gears of different modules cannot mesh together; always match the module of your replacement gear to the existing drivetrain.
Yes. Mod 1 spur gears are widely used in DIY CNC routers, 3D printer extruder drives, and laser cutter axis systems. Verify the bore matches your stepper or servo motor shaft, and confirm the face width is compatible with your existing gear or rack width.
Pack quantity varies by the variant selected. Choose your required packing quantity (e.g. 20 Pcs) from the options above before adding to cart. Bulk packs offer better per-unit value for workshop stock or production use.
