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When a mismatched gear slips mid-run or a soft-metal tooth strips under load, the whole build stops. Engineers, hobbyist makers, and small-batch manufacturers who need a reliable, drop-in spur gear — sized exactly to their shaft — reach for a module 1 steel gear that holds tolerance under real operating conditions.
These module 1 spur gears are machined from 45# medium-carbon steel and cover a wide tooth range from 45 T up to 150 T, with pitch circle diameters scaling proportionally (45 mm – 150 mm / approx. 1.77 in – 5.91 in). Bore options span 6 mm to 30 mm (approx. 0.24 in – 1.18 in) to suit common motor and shaft standards. Face width is typically 10–15 mm depending on tooth count; larger tooth counts use a stepped hub design (step heights of 40 mm or 70 mm noted in variant options).
Typical use cases include DC motor gearbox assemblies for robotics and automation, CNC axis drive trains requiring consistent backlash control, and DIY power-transmission projects such as go-kart reducers, conveyor drives, and 3D-printer extruder upgrades where a standard module 1 spur gear with a keyed or set-screw bore is the fastest path to a working drivetrain.
| Module | 1 (1M) |
|---|---|
| Tooth Count Range | 45 T – 150 T (see variant options) |
| Pressure Angle | 20° |
| Pitch Circle Diameter | 45 mm – 150 mm (1.77 in – 5.91 in) |
| Bore Diameter | 6 mm – 30 mm (see variant options) |
| Face Width | See variant options |
| Hub Step Height | 40 mm or 70 mm (120 T & 150 T variants only) |
| Material | 45# Medium-Carbon Steel |
| Tooth Form | Involute, hobbed |
| Finish | Natural / lightly oiled |
| Quantity per Order | 1 Pcs (as selected) |
Divide the driven gear tooth count by the driver gear tooth count to get your reduction ratio. For example, pairing a 1M 45T pinion with a 1M 90T gear gives a 2:1 reduction. Select tooth counts that achieve your target ratio while keeping both gears within the physical space of your build.
Yes. All gears in this listing follow the standard Module 1 involute tooth profile with a 20° pressure angle, which is fully interchangeable with any other correctly manufactured 1M spur gear or rack regardless of brand.
Measure your motor or drive shaft outer diameter with a caliper. Choose the bore option that matches — for example, a 6 mm shaft needs the 6 mm bore variant. If you need a keyway or set-screw flat, the bore can be machined further in your own shop after delivery.
45# medium-carbon steel has a tensile strength of approximately 600–800 MPa in the normalized condition and can be further hardened. For high-torque or high-cycle applications, consider surface hardening the gear after machining any bore modifications. Actual load capacity depends on operating speed, lubrication, and mating gear quality.
45# steel is not inherently stainless. For outdoor or humid environments, apply a light machine oil, grease, or a zinc-phosphate coating after installation. For fully corrosion-resistant applications, consider stainless steel or nylon gears instead.
Both are 120-tooth Module 1 gears, but the hub step height differs — 40 mm vs. 70 mm. The step height determines how far the gear body is offset from the mounting face. Choose the step height that provides the correct axial clearance for your shaft and housing geometry.
Yes. Module 1 spur gears are widely used in extruder drives, Z-axis lead-screw couplings, and CNC rotary axis assemblies. Verify that the bore matches your stepper or servo shaft, and confirm the tooth count gives you the desired step-per-mm or gear ratio for your motion system.
