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When your motion-control build demands repeatable accuracy and zero slop, a poorly toleranced gear becomes the weakest link in the entire drivetrain. Engineers, makers, and small-batch manufacturers who rely on CNC routers, robotic arms, conveyor systems, or custom motor mounts need a spur gear that holds its pitch circle under load — not one that introduces backlash after a few hundred cycles. These 1 Mod spur pinion gears with step keyway bore are machined for builders who cannot afford to compromise on dimensional consistency.
Each gear is machined from 45#C medium-carbon steel, heat-treated for surface hardness while retaining a tough core. The module is 1M (metric), with tooth counts ranging from 20T to 150T, giving pitch diameters from approximately 20 mm (0.79 in) up to 150 mm (5.91 in). The step keyway bore accommodates standard metric keyway dimensions — bore sizes span 8 mm through 30 mm depending on the model, with keyway widths of 3×1.4 mm, 4×1.8 mm, 5×2.3 mm, 6×2.8 mm, or 8×3.3 mm to match your shaft standard.
Typical use cases include 1 Mod spur gear sets for DIY CNC gantry drives, stepper and servo motor pinion replacements in 3D printer extruder gearboxes, and precision reduction stages in tabletop robotic arm joints. The step bore design simplifies axial positioning on stepped shafts, making these gears a practical choice for compact motor-to-shaft assemblies where a standard through-bore would require additional collars.
Machined from medium-carbon 45#C steel with surface hardening for wear resistance and a tough core that absorbs shock loads in cyclic drive applications.
Wide Tooth-Count Range (20T – 150T)A single product line covers gear ratios from compact 20-tooth pinions up to large 150-tooth wheels, letting you source matched pairs without switching suppliers.
Step Keyway BoreThe stepped bore profile seats directly on a stepped shaft, eliminating the need for additional spacers or collars and reducing assembly time in tight motor housings.
Multiple Bore & Keyway SizesBore options from 8 mm to 30 mm with keyway widths of 3×1.4 mm through 8×3.3 mm cover the most common metric shaft standards used in stepper motors, servo motors, and gearbox output shafts.
Precision-Cut Tooth ProfileModule 1M involute tooth geometry ensures smooth meshing, consistent pitch, and low noise when paired with a correctly spaced mating gear or rack.
Broad Application CompatibilitySuited for CNC routers, 3D printer extruder drives, robotic arm joints, conveyor indexing systems, and custom motor-to-shaft reduction stages requiring a standard 1M pitch.
| Module | 1M (Metric) |
|---|---|
| Tooth Count Range | 20T – 150T (see variant options) |
| Material | 45#C Medium-Carbon Steel |
| Surface Treatment | Heat-treated (surface hardened) |
| Bore Type | Step Keyway Bore |
| Bore Size Range | 8 mm – 30 mm (see variant options) |
| Keyway Width × Depth | 3×1.4 mm / 4×1.8 mm / 5×2.3 mm / 6×2.8 mm / 8×3.3 mm (see variant options) |
| Pitch Diameter Range | Approx. 20 mm – 150 mm (0.79 in – 5.91 in) |
| Pressure Angle | 20° (standard involute) |
| Gear Type | External Spur Gear / Pinion |
| Face Width | See variant options |
| Weight | See variant options |
The tooth count determines the pitch diameter (PD = Module × Teeth = 1 × T mm) and the gear ratio when paired with a mating gear. For a motor pinion, choose a smaller tooth count (e.g., 20T–30T) to drive a larger gear and achieve speed reduction. For direct-drive or 1:1 applications, match the tooth count on both gears. Confirm center distance = (T1 + T2) / 2 mm for a 1M pair.
Measure your motor or gearbox output shaft diameter precisely with calipers. Then match the bore size listed in the variant options (e.g., 8 mm, 10 mm, 12 mm). The keyway dimension (e.g., 4×1.8 mm) must match the key already cut on your shaft — refer to your shaft's engineering drawing or the motor datasheet for the keyway standard.
A step bore has a larger-diameter counterbore on one face that seats against a shoulder on a stepped shaft. This locates the gear axially without requiring a separate spacer, collar, or snap ring, which simplifies assembly in compact motor housings and reduces total part count.
The gears are machined from 45#C medium-carbon steel and surface-hardened, giving a good balance of surface wear resistance and core toughness. For exact load ratings (tangential force, bending stress), apply standard AGMA or ISO 6336 gear strength calculations using the tooth geometry and your operating conditions. These gears are suited for light-to-medium duty CNC, robotics, and automation loads typical of stepper and servo motor drives.
45#C steel without additional coating has moderate corrosion resistance suitable for indoor, dry environments. For humid or outdoor applications, apply a light machine oil or grease to the tooth faces and bore after installation. If your application requires higher corrosion resistance, consider stainless steel or coated alternatives.
Yes — any gear or rack with a 1 Module (1M) pitch and a standard 20° pressure angle will mesh correctly with these pinions. Ensure the center distance between the two gear axes equals (T_pinion + T_gear) / 2 mm. If you are replacing an existing gear, verify the module marking on the original part before ordering.
Yes, provided the bore size matches the motor shaft diameter. NEMA 17 motors typically have a 5 mm shaft (no keyway), while NEMA 23 motors commonly use 6.35 mm or 8 mm shafts. Select the bore size that matches your motor shaft and confirm the keyway dimensions align with any key cut on the shaft. For plain shafts without a keyway, a set-screw collar or Loctite retaining compound may be used instead.
