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When your build demands exact gear meshing and zero slop, a mismatched or undersized spur gear can derail an entire project. Whether you're a robotics engineer, RC vehicle builder, CNC hobbyist, or mechanical DIYer, finding a 1 module spur gear with the right tooth count and bore diameter in a single order is often the biggest bottleneck. This listing solves that problem with a wide selection of 45# steel pinion gears with step, covering tooth counts from 10T to 150T and bore sizes from 4mm to 20mm.
Each gear is machined from 45# carbon steel — a medium-carbon steel known for its balance of hardness, toughness, and machinability. The step design integrates a reduced-diameter hub section, allowing secure shaft seating and set-screw locking without additional spacers. Gear outer diameters range from approximately 12mm (10T) to 152mm (150T), with step diameters spanning 0mm to 50mm depending on the variant. Bore sizes available: 4mm, 5mm, 6mm, 6.35mm, 7mm, 8mm, 10mm, 12mm, 12.7mm, 14mm, 15mm, 16mm, 17mm, 19mm, and 20mm.
Typical use cases include custom gearbox assemblies for wheeled robots and RC crawlers, lead-screw drive stages in DIY CNC routers and 3D printer extruder systems, and torque-transfer mechanisms in automated conveyor or actuator builds — all applications where a 1 mod steel spur gear with step bore delivers reliable, repeatable engagement.
Machined from 45# medium-carbon steel for a reliable balance of surface hardness and core toughness — suitable for moderate-to-high load drive applications.
Covers an extensive gear ratio range in a single product family, from compact 10-tooth pinions to large 150-tooth driven gears — ideal for custom ratio tuning.
Bore options from 4mm to 20mm (including 6.35mm / 1/4" and 12.7mm / 1/2" imperial sizes) accommodate a broad range of motor and shaft standards.
The stepped hub section provides a positive axial stop for shaft positioning and a flat for set-screw engagement, reducing assembly complexity and improving concentricity.
Conforms to the international Module 1 gear standard, ensuring direct mesh compatibility with any other 1 Mod rack, pinion, or spur gear regardless of brand.
Each variant is sold as a single gear, letting you order exactly the tooth count and bore combination you need without paying for extras you don't.
| Module | 1 (Mod 1) |
|---|---|
| Tooth Count Range | 10T – 150T (see variant options) |
| Material | 45# Carbon Steel |
| Bore Diameter Range | 4mm – 20mm (see variant options) |
| Step Diameter Range | 0mm – 50mm (see variant options) |
| Pressure Angle | 20° |
| Outer Diameter (approx.) | (Tooth Count + 2) × 1mm |
| Finish | Natural steel / lightly oiled |
| Quantity per Order | 1 piece |
| Compatibility | Module 1 gear systems |
The tooth count determines your gear ratio. Divide the driven gear's tooth count by the driving gear's tooth count to get the ratio. For example, a 10T pinion driving a 50T gear gives a 5:1 reduction. Select tooth counts based on the torque and speed requirements of your build. Smaller pinions (10T–20T) are common on motor shafts; larger gears (50T–150T) are used as driven wheels or idlers.
Measure your motor or drive shaft diameter precisely with calipers. Common motor shaft sizes include 4mm, 5mm, 6mm, 6.35mm (1/4"), 8mm, and 10mm. The bore must match your shaft diameter exactly — a loose bore will cause runout and slipping. If your shaft is imperial (e.g., 1/4" or 1/2"), select the 6.35mm or 12.7mm bore options respectively.
The step is a reduced-diameter hub section machined into the gear body. It acts as a shoulder stop for axial positioning on the shaft and provides a flat surface for a set screw. If your design requires a flush or recessed gear mount, or if you need a positive axial stop without a separate collar, choose a variant with a step diameter. If your mounting arrangement doesn't require a step, the 0mm step variants are plain-hub gears.
These gears are machined from 45# carbon steel, which has a tensile strength of approximately 600–700 MPa in its normalized state. They are suitable for moderate-to-high torque applications in robotics, RC vehicles, and light industrial automation. For very high-shock or continuous heavy-load applications, consider whether a hardened or alloy steel gear would be more appropriate for your specific duty cycle.
45# carbon steel is not inherently corrosion resistant. The gears are supplied with a light oil coating to prevent surface rust during storage and transit. For outdoor or humid environments, apply a suitable gear lubricant or grease during installation, and consider periodic re-lubrication. For corrosive environments, stainless steel or plastic gears may be more appropriate.
Yes. These gears conform to the international Module 1 standard with a 20° pressure angle, which is the most widely used metric gear standard globally. They will mesh correctly with any other Module 1 spur gear, rack, or pinion — regardless of brand — as long as the module and pressure angle match. Do not attempt to mesh Module 1 gears with Module 0.8, Module 1.25, or other module sizes.
For two Module 1 spur gears, the center distance (in mm) is simply: (Tooth Count of Gear 1 + Tooth Count of Gear 2) ÷ 2. For example, a 20T and a 40T gear would require a center distance of (20 + 40) ÷ 2 = 30mm. This formula applies to standard (non-profile-shifted) Module 1 gears with a 20° pressure angle.
