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When a slipping or undersized gear throws off your entire drivetrain, the downstream damage — stripped teeth, misaligned shafts, lost torque — costs far more than the part itself. Hobbyists, robotics builders, and small-machine engineers who need a dimensionally consistent, metal-bodied pinion gear will find this 0.5 module brass spur gear a dependable drop-in solution.
Each gear is machined from brass, offering a balance of machinability, moderate corrosion resistance, and low-noise meshing. The gear features 38 teeth at 0.5 module (Mod 0.5), with a pitch diameter of 19 mm (approx. 0.748 in). Bore options span 4 mm to 12 mm (approx. 0.157 in to 0.472 in), covering the most common motor shaft diameters used in compact drive applications. Overall gear width is typically 5–8 mm depending on bore variant.
Typical use cases include RC car transmission pinion replacement, stepper motor output gears in 3D printer extruder assemblies, and compact robotic joint actuators requiring a 0.5 mod 38-tooth spur gear with a defined bore-to-shaft fit.
Machined from brass for reliable torque transmission, quiet meshing, and resistance to surface oxidation in typical indoor environments.
19 mm pitch diameter with 38 evenly spaced teeth at Mod 0.5 — compatible with the full range of 0.5 module gear systems used in compact drives.
Available in bore diameters of 4, 5, 6, 6.35, 7, 8, 10, and 12 mm to match standard motor shaft sizes without custom machining.
Designed as a drop-in pinion gear for RC vehicles, extruder drives, and small automation systems where Mod 0.5 gearing is specified.
Order as 1, 2, 5, or 10-piece packs — ideal for prototyping single builds or stocking spares for production runs.
Each gear is produced to consistent tooth profile and bore tolerances, reducing backlash variation across multi-gear assemblies.
| Module | 0.5 |
|---|---|
| Number of Teeth | 38T |
| Pitch Diameter | 19 mm (0.748 in) |
| Bore Diameter | 4 / 5 / 6 / 6.35 / 7 / 8 / 10 / 12 mm — See variant options |
| Material | Brass |
| Gear Type | Spur Gear (Pinion) |
| Pressure Angle | 20° |
| Face Width | See variant options |
| Hub Style | See variant options |
| Finish | Natural brass (uncoated) |
| Pack Quantity | 1 / 2 / 5 / 10 PCS — See variant options |
Measure your motor or drive shaft diameter with a caliper. Select the bore option that matches exactly — for example, a 5 mm shaft requires the Bore 5 mm variant. If your shaft is imperial (e.g., 1/4 in = 6.35 mm), choose the 6.35 mm bore option. A loose bore fit will cause shaft slippage under load.
Brass spur gears at Mod 0.5 are well-suited for light-to-medium duty applications such as RC drivetrains, 3D printer extruders, and small robotic joints. For high-torque or continuous industrial duty cycles, consider steel gears. Brass offers quieter operation and adequate strength for most hobbyist and maker use cases.
Brass has inherent corrosion resistance in dry and typical indoor environments. Surface tarnishing (oxidation) may occur over time but does not significantly affect mechanical performance. For outdoor or high-humidity applications, periodic light lubrication is recommended.
This gear meshes with any Mod 0.5 spur or helical gear of the same pressure angle (20°). The mating gear tooth count determines the gear ratio. For example, pairing with a 19T pinion gives a 2:1 reduction ratio. Ensure the mating gear's face width and bore alignment are compatible with your assembly.
For single prototype builds or one-off repairs, the 1 PCS option is sufficient. If you are building a multi-gear assembly or want a spare on hand, 2 PCS is practical. The 5 PCS and 10 PCS packs offer a lower per-unit cost and are suited for small production runs, classroom kits, or stocking spare parts for ongoing projects.
The bore is machined for a close sliding or light interference fit on the shaft. Whether you use a set screw, retaining ring, or press-fit depends on your assembly design. The gear does not include a pre-drilled set screw hole unless specified in the variant listing — check the variant details or contact us to confirm before ordering.
Yes. 6.35 mm is the metric equivalent of 1/4 inch (0.250 in), making the Bore 6.35 mm variant the correct choice for standard 1/4-inch motor shafts commonly found in North American hobby motors and small DC gearmotors.
