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When a stripped or undersized gear stalls your build, every millimeter of bore tolerance matters. Makers, robotics engineers, and RC hobbyists working with compact 0.5-module drive trains need a pinion gear that fits precisely, transmits torque cleanly, and resists wear over thousands of cycles — without corroding in mixed-environment use.
This 0.5 Mod 24-tooth spur gear is machined from steel with a black oxide surface treatment. The outer diameter measures 13mm (approx. 0.51 in), and bore options of 4mm, 5mm, and 6mm (approx. 0.157–0.236 in) cover the most common motor shaft sizes in this module class. Tooth count is fixed at 24T with a 0.5 module pitch, giving a pitch diameter of 12mm (0.472 in).
Typical applications include RC car pinion-to-spur mesh assemblies, small robotic joint actuators requiring a 0.5-module gear ratio stage, and compact automation mechanisms where a 13mm OD steel spur gear with a defined bore is required for shaft-to-gear coupling without set screws.
Available in 4mm, 5mm, and 6mm bore diameters to match common motor shaft sizes in 0.5-module drive systems — select your exact bore above.
Steel body with black oxide finish provides corrosion resistance and reduces surface friction compared to bare steel, extending service life in mixed-humidity environments.
Machined to 0.5 module standard with 24 teeth, yielding a 12mm pitch diameter and 13mm outer diameter — dimensionally consistent for repeatable gear mesh.
Uniform tooth spacing and steel rigidity support consistent torque transfer in high-cycle applications such as robotics joints and RC drivetrain assemblies.
Available in 1, 3, 5, or 10-piece quantities — order a single replacement or stock multiples for prototyping, repair kits, or production runs.
13mm OD and standard 0.5-module tooth form make this gear a direct dimensional replacement for worn pinion gears in compatible 0.5-module gear trains.
| Module | 0.5 |
|---|---|
| Tooth Count | 24T |
| Pitch Diameter | 12mm (0.472 in) |
| Outer Diameter (OD) | 13mm (0.512 in) |
| Bore Diameter | 4mm / 5mm / 6mm (See variant options) |
| Material | Steel |
| Surface Finish | Black Oxide |
| Gear Type | Spur Gear (Pinion) |
| Pressure Angle | 20° (standard) |
| Hub / Face Width | See variant options |
| Pack Quantity | 1 / 3 / 5 / 10 pcs (See variant options) |
Measure the outer diameter of your motor or drive shaft with calipers. The bore must match your shaft diameter exactly for a secure fit. A 4mm bore suits most small DC and stepper motor shafts in micro robotics; 5mm and 6mm are common in larger RC car motors and servo-driven mechanisms. If your shaft uses a set screw or keyway, confirm the hub depth accommodates it.
This gear uses the standard 20° pressure angle. For proper meshing, both the pinion and the mating spur gear must share the same module (0.5) and pressure angle (20°). Mixing pressure angles — even at the same module — will cause poor tooth contact, noise, and accelerated wear.
Black oxide provides mild corrosion resistance and reduces surface friction, but it is not equivalent to zinc plating or stainless steel for prolonged outdoor or wet exposure. For occasional humidity or indoor use it performs well. In continuously wet or salt-spray environments, consider applying a light machine oil to the gear surface periodically to maintain protection.
Yes — any 0.5-module, 20° pressure angle spur gear will mesh with this steel pinion regardless of material, provided the center distance is set correctly. Steel-on-plastic pairings are common in RC and robotics applications where the plastic gear acts as the sacrificial wear component, protecting the motor shaft from shock loads.
Center distance = (Pinion pitch diameter + Mating gear pitch diameter) ÷ 2. For this 24T gear, pitch diameter = 12mm. If your mating gear is, for example, a 0.5 Mod 48T gear (pitch diameter 24mm), center distance = (12 + 24) ÷ 2 = 18mm. Always verify with calipers after assembly to ensure smooth, backlash-controlled mesh.
Yes. This 0.5 Mod 24T pinion is well-suited as the input stage in a multi-stage reduction, driving a larger spur gear on an intermediate shaft. Ensure each stage uses matched 0.5-module gears and that shaft alignment is maintained across stages to prevent binding and uneven tooth load.
For initial prototyping or a single build, the 1-piece option lets you validate fit and mesh before committing. The 3-piece or 5-piece packs are practical for iterative testing or small batch builds. The 10-piece pack offers the best per-unit value for production runs, repair stock, or team builds where multiple assemblies share the same gear specification.
