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When your motion system demands consistent torque transfer and dimensional accuracy, a poorly matched gear becomes the weakest link. Whether you're building a CNC router, a robotic arm, or a custom conveyor, this 1 Module 45# carbon steel spur gear gives engineers, makers, and workshop professionals a reliable, off-the-shelf solution across a wide tooth count range.
Each gear is machined from 45# medium carbon steel, offering a good balance of hardness and machinability. The module is 1M (1 mm per tooth pitch), with tooth counts spanning 50T to 150T and bore diameters ranging from 6 mm (0.24 in) to 30 mm (1.18 in). Keyway bore variants include 3×1.4 mm, 4×1.8 mm, 5×2.3 mm, 6×2.8 mm, and 8×3.3 mm keyway slots to suit standard shaft-key configurations. Step bore variants (40 mm step) are also available for select sizes.
Typical applications include 1 mod spur gear for stepper motor shaft coupling, CNC axis drive gear replacement, 3D printer extruder gear upgrade, and light-duty industrial conveyor pinion gear. The broad bore and tooth count selection makes it straightforward to match an existing drivetrain or design a new one from scratch.
Machined from 45# medium carbon steel for a solid combination of tensile strength and wear resistance suited to moderate-load drive applications.
Module 1 pitch (1 mm per tooth) ensures direct interchangeability with any standard 1M rack, pinion, or mating spur gear in your drivetrain.
Seventeen tooth count options from 50T to 150T let you dial in the exact gear ratio needed for your CNC, robotics, or automation project.
Plain bore (6–30 mm) and keyway bore variants (3×1.4 mm up to 8×3.3 mm) accommodate a wide range of shaft sizes and torque-locking requirements.
Select 1M 52T models include a 40 mm step bore option, useful for applications requiring a shoulder or spacer fit on the shaft.
Suitable for CNC routers, 3D printers, robotic joints, conveyor drives, and general-purpose DIY mechanical builds requiring a standard metric spur gear.
| Module | 1M (1 mm/tooth) |
|---|---|
| Material | 45# Carbon Steel |
| Tooth Count Range | 50T – 150T (17 options) |
| Bore Diameter Range | 6 mm – 30 mm (0.24 in – 1.18 in) |
| Keyway Options | 3×1.4 mm / 4×1.8 mm / 5×2.3 mm / 6×2.8 mm / 8×3.3 mm |
| Step Bore | 40 mm step (select 1M 52T variants) |
| Pressure Angle | See variant options |
| Face Width | See variant options |
| Surface Finish | See variant options |
| Gear Type | External Spur Gear |
| Pitch System | Metric (Module) |
The tooth count determines your gear ratio. Divide the driven gear teeth by the driving gear teeth to get the ratio. For example, pairing a 50T gear with a 25T pinion gives a 2:1 reduction. Choose a higher tooth count for more torque and lower speed, or a lower count for higher speed with less torque.
Measure your shaft outer diameter (OD) precisely with calipers. Select the bore that matches your shaft OD exactly. If your shaft uses a key for torque locking, choose the corresponding keyway bore variant (e.g., 14mm(5×2.3mm) means a 14 mm bore with a 5×2.3 mm keyway slot).
A plain bore (e.g., "14mm") is a smooth cylindrical hole — typically secured with a set screw or press fit. A keyway bore (e.g., "14mm(5×2.3mm)") has a rectangular slot machined into the bore that accepts a matching key on the shaft, providing a positive torque-locking connection suitable for higher-load applications.
45# carbon steel (equivalent to AISI 1045) has a tensile strength of approximately 600–800 MPa in its normalized state. It is well-suited for moderate-load, low-to-medium speed spur gear applications such as CNC routers, 3D printers, and light conveyor drives. For heavy industrial or high-shock loads, consider heat-treated or alloy steel gears.
Yes — as long as your existing rack, pinion, or mating gear is also Module 1 (1M) with a standard 20° pressure angle, these gears will mesh correctly. Always verify the module and pressure angle of your existing components before ordering.
The step bore variant (available on select 1M 52T models, 40 mm step) features a bore that transitions to a larger diameter at a set depth. This is useful when you need the gear to seat against a shoulder on the shaft or when a spacer or collar is required for axial positioning. If your shaft is a straight cylinder without a shoulder, the standard plain or keyway bore is the correct choice.
45# carbon steel is not inherently corrosion-resistant. For outdoor or humid environments, apply a suitable lubricant or anti-rust coating, or consider stainless steel or plastic gears instead. Regular maintenance and lubrication will significantly extend service life in moist conditions.
