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When your CNC router, robotic arm, or automation rig demands consistent torque transfer without slop or backlash, the wrong gear becomes the weakest link in your entire drivetrain. Engineers, makers, and machine builders who need repeatable, low-noise motion rely on properly specified 1 Mod steel spur gears with step bore to keep their builds running true.
These 1 Mod spur gears are machined from 45# carbon steel, offering a solid balance of hardness and machinability. The stepped bore design accommodates standard shaft diameters ranging from 8 mm (0.31 in) to 30 mm (1.18 in), with keyway options (4×1.8 mm, 5×2.3 mm, and 6×2.8 mm, 8×3.3 mm) available across the range. Tooth counts span 90T through 150T with a 1M (Module 1) pitch, and step heights run from 30 mm to 70 mm depending on the variant selected.
Typical use cases include: replacing worn pinion gears on CNC plasma or router tables, building custom gearbox stages for stepper or servo motor drives, and constructing indexing or rotary-axis assemblies for 3D printer upgrades and robotic joint mechanisms.
Machined from medium-carbon 45# steel for a reliable combination of surface hardness and core toughness — suitable for continuous-duty motor drive applications.
Choose from 90, 100, 120, 130, or 150 tooth configurations to dial in your gear ratio. More teeth mean smoother, quieter operation at higher speeds.
The integrated step bore accepts shaft diameters from 8 mm to 30 mm. Keyway slots (4×1.8 mm, 5×2.3 mm, 6×2.8 mm, 8×3.3 mm) prevent rotational slip under load — critical for servo and stepper motor pinion applications.
Fully compatible with the international Module 1 gear standard. Pairs directly with 1M racks, worm gears, and mating spur gears without custom adaptation.
Step heights of 30 mm, 40 mm, 50 mm, 55 mm, and 70 mm are offered across variants, giving you flexibility to match motor shaft protrusion and housing clearance requirements.
Dimensionally consistent across the range, making these gears straightforward replacements or upgrades in existing 1M gear trains on CNC machines, robotic joints, and automated conveyor systems.
| Module | 1M (Module 1) |
|---|---|
| Tooth Count | 90T / 100T / 120T / 130T / 150T (see variant options) |
| Material | 45# Carbon Steel |
| Bore Diameter Range | 8 mm – 30 mm (0.31 in – 1.18 in) |
| Keyway Options | 4×1.8 mm / 5×2.3 mm / 6×2.8 mm / 8×3.3 mm (see variant options) |
| Step Height Range | 30 mm – 70 mm (1.18 in – 2.76 in) |
| Pressure Angle | 20° |
| Pitch Diameter | See variant options |
| Surface Finish | See variant options |
| Gear Type | External Spur Gear |
| Application | CNC machines, robotics, automation, motor pinion drives |
Tooth count determines your gear ratio when paired with a pinion or mating gear. A higher tooth count on the driven gear produces more torque and lower output speed. For example, pairing a 90T gear with a 9T pinion gives a 10:1 reduction. Calculate your required ratio first, then select the tooth count that achieves it within your available space envelope.
Match the bore diameter to your motor or shaft OD. Then select the keyway that corresponds to your shaft's key slot: 4×1.8 mm is common on smaller shafts (8–12 mm), 5×2.3 mm on mid-range shafts (12–17 mm), 6×2.8 mm on 18–22 mm shafts, and 8×3.3 mm on 24–30 mm shafts. Refer to your shaft's engineering drawing or measure with calipers before ordering.
A stepped bore means the gear hub has a counterbore — a larger-diameter recess on one face — that allows the gear to sit flush against a motor face or housing shoulder. This simplifies axial positioning and reduces the need for additional spacers. The step height dimension (30–70 mm) tells you how deep this recess is.
45# carbon steel offers a tensile strength typically in the 600–800 MPa range, making it well-suited for moderate-load continuous-duty applications such as CNC axis drives, conveyor pinions, and robotic joint actuators. For very high-shock or heavy-industrial loads, consider whether a hardened or alloy steel gear would be more appropriate for your specific torque and speed requirements.
Carbon steel is susceptible to surface oxidation in humid or wet environments. For indoor CNC or robotics use, standard lubrication (grease or gear oil) provides adequate protection. For outdoor or high-humidity applications, consider applying a corrosion-inhibiting coating or selecting a stainless steel alternative if long-term exposure is expected.
Yes. Module 1 is an internationally standardized pitch, so these gears will mesh correctly with any other Module 1 external spur gear, rack, or compatible component — regardless of brand — as long as the pressure angle is also 20°. Always confirm the mating gear's module and pressure angle before assembly.
A plain bore (no keyway) relies on a set screw or interference fit to transmit torque — suitable for light loads or where the shaft has a flat. A keyway bore uses a physical key to positively lock the gear to the shaft, preventing rotational slip under higher torque or reversing loads. For motor pinion applications with significant torque, a keyway variant is strongly recommended.
