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When a stripped or undersized gear brings your build to a halt, you need a replacement that fits exactly and holds up under load. These Mod1 steel pinion spur gears are designed for makers, robotics builders, RC hobbyists, and mechanical engineers who demand dimensional accuracy and repeatable performance across every variant.
Each gear is machined from hardened steel and offered in a wide selection of tooth counts (10T–39T) and bore diameters (4mm–20mm / 0.16"–0.79"). Round-bore variants accept a grub screw for shaft locking; D-hole and key-slot variants provide positive anti-rotation engagement. Outer diameters range from approximately 12mm to 41mm (0.47"–1.61") depending on tooth count, following standard Mod1 geometry.
Typical use cases include DC motor pinion replacement in RC cars and trucks, drive-train reduction stages in desktop CNC and 3D printer extruder assemblies, and custom gearbox builds for robotics competition platforms where a specific tooth-count-to-bore combination is required.
Machined from carbon steel with surface hardening for wear resistance under continuous rotational load.
Wide Tooth Count Range (10T–39T)Covers common reduction ratios for RC drivetrains, robotics, and DIY gearboxes in a single product family.
Multiple Bore Options (4–20mm)Round bore, D-hole, and key-slot variants available — select the bore type that matches your motor shaft.
Grub Screw Included (Round Bore)Round-bore gears ship with a set screw for secure shaft locking without additional hardware.
Standard Mod1 Geometry20° pressure angle, Mod1 pitch — directly interchangeable with any Mod1 rack or mating gear in your system.
Single-Piece or Bulk PackAvailable in 1 PCS or 100 PCS quantities to suit prototyping and production runs alike.
| Module | Mod1 (Module 1) |
|---|---|
| Pressure Angle | 20° |
| Tooth Count Range | 10T – 39T |
| Bore Diameter Range | 4mm – 20mm (0.16" – 0.79") |
| Bore Types | Round bore, D-hole, Key slot |
| Outer Diameter (approx.) | 12mm – 41mm (varies by tooth count) |
| Material | Hardened carbon steel |
| Finish | See variant options |
| Shaft Locking | Grub screw (round bore); D-flat / key slot (other variants) |
| Quantity per Order | 1 PCS or 100 PCS (select above) |
| Weight (per piece) | See variant options |
The gear ratio is determined by dividing the driven gear tooth count by the driving (pinion) gear tooth count. For example, a 10T pinion driving a 30T gear gives a 3:1 reduction. Choose a tooth count that achieves your target ratio while keeping the pinion large enough to avoid undercutting — typically 10T or more for Mod1 gears.
Round bore gears use a grub screw to clamp onto a smooth shaft — easy to install and reposition. D-hole gears have a flat cut on one side of the bore that matches a D-shaft, providing positive anti-rotation without a set screw. Key-slot gears accept a standard Woodruff or parallel key for high-torque applications where slippage must be eliminated.
Yes. The gears are machined from hardened carbon steel, which provides significantly higher strength and wear resistance than brass or plastic alternatives commonly found in entry-level RC kits. They are suitable for 1/10 and 1/8 scale electric RC drivetrains running brushless motors up to moderate power levels. For extreme-power builds, verify the bore and face width match your motor pinion spec.
Yes, as long as your existing gear is also Mod1 with a 20° pressure angle. Module 1 is a standardized metric gear system, so any Mod1 gear will mesh correctly with another Mod1 gear regardless of manufacturer. Confirm the module and pressure angle of your existing gear before ordering.
Use a digital caliper to measure the shaft diameter at the point where the gear will sit. For round shafts, select the matching round bore size. For D-shafts, measure both the full diameter and the flat-to-round distance — these correspond to the D-hole dimensions listed (e.g., 5×4.5mm means 5mm full diameter, 4.5mm flat-to-round). For key-slot shafts, measure the shaft diameter and key width.
Yes. Mod1 steel pinion gears are widely used in extruder drive assemblies, Z-axis lead screw couplings, and CNC axis reduction stages. Select the tooth count and bore that match your stepper motor shaft and the mating gear in your assembly. The hardened steel construction handles the continuous duty cycles typical of these applications.
Each listing is available in 1 PCS for prototyping or single replacements, and in 100 PCS packs for production runs or stocking purposes. The 100 PCS option is currently available for the 16T / 8mm bore variant. Select your preferred quantity in the Qty option above before adding to cart.
