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When your motor drive, robotic arm, or CNC axis demands consistent torque transfer without slop or premature wear, the wrong gear becomes the most expensive part in your build. These Mod 1 stainless steel spur gears are engineered for makers, engineers, and hobbyists who need reliable pinion gear performance across a wide range of shaft sizes and tooth counts — without sourcing from multiple suppliers.
Each gear is machined from stainless steel, offering corrosion resistance and structural rigidity. The Mod 1 (1M) tooth profile ensures standard metric compatibility across the full range of 31 to 50 teeth. Bore options span 8 mm (0.31 in) to 20 mm (0.79 in), with plain round bores and keyway variants available — keyway slots range from 3×1.4 mm up to 6×2.8 mm depending on bore size, enabling positive shaft locking without set-screw slippage.
Typical use cases include DC motor pinion drives in robotics and automation rigs, lead-screw stage drives in DIY CNC routers and laser cutters, and gear-reduction assemblies in electric go-karts, conveyor systems, and custom actuators where a standard Mod 1 spur gear mesh is required.
| Module (Mod) | 1 (Mod 1 / 1M) |
|---|---|
| Tooth Count Range | 31T – 50T (see variant options) |
| Bore Diameter Range | 8 mm – 20 mm (0.31 in – 0.79 in) |
| Bore Type | Plain round bore; Keyway bore (see variant options) |
| Keyway Sizes Available | 3×1.4 mm, 4×1.8 mm, 5×2.3 mm, 6×2.8 mm (bore-dependent) |
| Material | Stainless Steel |
| Tooth Profile | Standard Metric Module 1 (involute) |
| Pressure Angle | 20° |
| Pitch Diameter | See variant options (= Teeth × Module = Teeth × 1 mm) |
| Face Width | See variant options |
| Finish | Natural stainless (uncoated) |
| Quantity per Order | 1 piece |
The tooth count determines your gear ratio. Divide the driven gear teeth by the driving gear (pinion) teeth to get the reduction ratio. For example, a 31T pinion driving a 62T gear gives a 2:1 reduction. Choose a higher tooth count for more torque and lower speed, or a lower tooth count for higher speed with less torque. All gears in this listing are Mod 1, so any two Mod 1 gears will mesh correctly regardless of tooth count.
Measure your motor or drive shaft diameter precisely with calipers. Select the bore that matches your shaft — available plain round bores are 8, 10, 12, 14, 15, 16, 17, 18, 19, and 20 mm. If your shaft uses a key for torque locking, select the corresponding keyway bore variant (e.g., Keyway 12/4×1.8 mm means a 12 mm bore with a 4 mm wide × 1.8 mm deep keyway slot).
For light-duty, low-torque, or unidirectional applications, a plain bore secured with a set screw is often sufficient. For reversing loads, high torque, or high-cycle applications — such as CNC axis drives or robotic joints — a keyway bore provides a positive mechanical lock that prevents rotational slip under load. If your shaft already has a machined keyway, select the matching keyway bore variant.
Yes. All gears in this listing use the standard Mod 1 (Module 1) involute tooth profile with a 20° pressure angle, which is the global metric standard. They will mesh correctly with any other Mod 1 spur gear, pinion, or rack regardless of brand, as long as the tooth profile and module match. Do not attempt to mesh Mod 1 gears with DP (diametral pitch) imperial gears — they are not interchangeable.
Stainless steel offers a good balance of tensile strength (typically 515–860 MPa depending on grade), corrosion resistance, and machinability. It is stronger than aluminum and more corrosion-resistant than carbon steel, making it well-suited for environments with moisture, mild chemicals, or food-adjacent use. For extremely high-torque industrial applications, consult the specific load ratings for your tooth count and face width.
For Mod 1 gears, the pitch diameter (PD) in millimeters equals the number of teeth (e.g., a 40T gear has a 40 mm PD). The center distance between two meshing Mod 1 gears equals (PD1 + PD2) / 2. For example, a 31T pinion (31 mm PD) meshing with a 40T gear (40 mm PD) requires a center distance of (31 + 40) / 2 = 35.5 mm. This makes layout calculations straightforward for any Mod 1 pair.
Stainless steel provides good corrosion resistance for outdoor, humid, and mildly wet environments. For prolonged submersion or highly corrosive chemical exposure, additional sealing or lubrication is recommended. Apply a light gear grease or oil to the tooth mesh to reduce wear and noise, especially in continuous-duty applications.
