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When a slipping or undersized gear causes your CNC router, 3D printer, or automation rig to lose steps and accuracy, the fix starts with the right pinion gear. These 2 Mod 45# steel spur gears are engineered for makers, machine builders, and automation engineers who need reliable, repeatable power transmission without compromise.
Each gear is machined from 45# medium-carbon steel, offering a solid balance of hardness and machinability. The module is 2M (2 mm per tooth), with tooth counts ranging from 12T to 35T and pitch circle diameters scaling accordingly — from approximately 24 mm (0.94 in) for 12T up to 70 mm (2.76 in) for 35T. Bore options span 8 mm to 30 mm, with keyway configurations (4 mm or 5 mm or 6 mm or 8 mm keyway depending on bore size) available for positive shaft engagement, plus plain bore and process-hole variants for custom fitting.
These spur gears are well-suited for stepper motor pinion drives in CNC routing tables, rack-and-pinion linear motion systems, robotic joint actuators, and light industrial conveyor drives. The standardized 2M tooth profile ensures direct interchangeability with matching 2 Mod racks, idlers, and mating gears across your build.
Machined from 45# carbon steel for a reliable combination of tensile strength and wear resistance — suited for continuous-duty motion control applications.
2M tooth geometry ensures direct mesh compatibility with standard 2 Mod racks and mating gears, simplifying system design and part sourcing.
Choose from 21 tooth-count options (12T through 35T) to dial in your gear ratio precisely — from compact high-speed pinions to larger torque-multiplying gears.
Plain bores (8 mm, 10 mm), keyed bores (12–30 mm with 4–8 mm keyways), and process-hole variants available — select the fit that matches your shaft without secondary machining.
Bore sizing and keyway dimensions are matched to common NEMA stepper and servo motor shaft standards, enabling direct mounting on most motion-control drives.
Use as a pinion on linear rack systems or as a rotary drive gear in gearhead assemblies — the standardized 2M profile works across both application types.
| Module | 2M (2 mm/tooth) |
|---|---|
| Material | 45# Medium-Carbon Steel |
| Tooth Count Range | 12T – 35T |
| Pitch Circle Diameter Range | 24 mm – 70 mm (0.94 in – 2.76 in) |
| Bore Diameter Range | 8 mm – 30 mm |
| Keyway Options | 4 mm, 5 mm, 6 mm, 8 mm (bore-dependent); plain bore and process hole also available |
| Pressure Angle | 20° |
| Gear Face Width | See variant options |
| Surface Finish | See variant options |
| Quantity per Order | 1 piece |
Tooth count determines your gear ratio and pitch circle diameter. For a rack-and-pinion CNC axis, a lower tooth count (12T–16T) gives finer resolution per motor step, while a higher count (20T–35T) increases linear speed per revolution. Match your tooth count to your desired travel speed and motor torque output. Pair with a 2M rack for linear motion or a mating 2M gear for rotary reduction.
Common NEMA 17 stepper motors have a 5 mm shaft — note that the smallest bore offered here is 8 mm, so a shaft adapter or coupler may be needed for NEMA 17. NEMA 23 motors typically use 6.35 mm or 8 mm shafts, and NEMA 34 motors commonly use 12.7 mm or 14 mm shafts. Select the bore that matches your motor shaft diameter; choose a keyway variant for positive torque transmission without set-screw slip.
45# carbon steel has a typical tensile strength of approximately 600–700 MPa and yield strength around 355 MPa, making it suitable for moderate-to-heavy duty motion control loads. For very high-cycle or shock-load applications, consider whether a hardened or alloy steel gear would better suit your requirements. These gears are designed for continuous-duty CNC, robotics, and automation use within standard 2M module load ratings.
45# carbon steel is not inherently corrosion resistant. For indoor, dry environments (typical CNC and robotics setups), the material performs well with standard lubrication. If your application involves moisture, coolant exposure, or outdoor conditions, apply a rust-inhibiting grease or consider a surface treatment such as zinc plating or black oxide coating after purchase.
Yes. These gears use a standard Module 2 (2M) tooth profile with a 20° pressure angle, which is the industry-standard geometry for 2M rack-and-pinion systems. They will mesh correctly with any 2M-compatible rack, idler, or mating gear that also uses a 20° pressure angle. Always verify the module and pressure angle of your mating components before assembly.
A plain bore (8 mm or 10 mm) is a smooth cylindrical hole — typically secured with a set screw or press fit. A keyway bore includes a machined slot that accepts a key for positive, non-slip shaft engagement — the preferred choice for driven gears under torque. A process hole is a rough-bored blank intended for custom machining to your exact shaft diameter and keyway spec — ideal when your shaft size falls outside the standard options listed.
Yes, this is one of the most common use cases. Select a tooth count that gives your desired linear travel per motor revolution (linear travel = π × module × tooth count per revolution), then pair with a matching 2M steel or nylon rack. For a typical CNC gantry, 20T–25T pinions offer a good balance of speed and resolution. Use a keyed bore variant to prevent shaft slip under cutting loads.
