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When a stripped plastic gear or an imprecise bore fit derails your build, the entire drivetrain pays the price. Hobbyists, robotics engineers, and RC vehicle builders who demand repeatable torque transfer and dimensional accuracy need a gear that holds tolerance under load — not one that wobbles or wears out after a few hundred cycles.
This 0.5 module brass pinion spur gear features 20 teeth and is available in three bore diameters: 4 mm (~0.157 in), 5 mm (~0.197 in), and 6 mm (~0.236 in). The gear body is machined from brass, offering a balance of machinability, moderate corrosion resistance, and low-friction meshing. Overall gear outer diameter is approximately 11 mm (~0.433 in) at 0.5 mod / 20T geometry, with face width typically in the 5–8 mm range depending on variant.
Typical use cases include: miniature RC car and truck motor pinion replacement, small robotic arm joint drives requiring a 0.5 mod gear mesh, and compact automation mechanisms such as camera pan/tilt rigs or conveyor micro-drives where a 20-tooth brass spur gear keeps noise and backlash low.
| Module | 0.5 |
|---|---|
| Number of Teeth | 20T |
| Bore Diameter | 4 mm / 5 mm / 6 mm (see variant options) |
| Outer Diameter (approx.) | ~11 mm (~0.433 in) |
| Face Width | See variant options |
| Material | Brass |
| Gear Type | Spur Gear (Pinion) |
| Pressure Angle | 20° |
| Packing Quantity | 1 / 2 / 5 / 10 PCS (see variant options) |
| Weight (per piece, approx.) | See variant options |
Measure your motor output shaft diameter with a caliper before ordering. The bore must match the shaft exactly for a secure press or set-screw fit. A 4 mm bore suits many micro-motor shafts; 5 mm and 6 mm are common on larger DC and stepper motors. If your shaft is between sizes, choose the smaller bore and ream to fit rather than using a larger bore with shims.
Yes. Module is a standardized metric measurement — any two gears sharing the same module (0.5) and pressure angle (20°) will mesh correctly regardless of material. This brass spur gear will mesh with 0.5 mod plastic, aluminum, or steel gears of any tooth count.
Brass sits between aluminum and mild steel in hardness. It handles moderate torque loads well and is significantly more durable than POM or nylon plastic gears. For high-torque or continuous-duty industrial applications, steel gears are recommended. For RC vehicles, robotics, and light automation — where low noise, corrosion resistance, and machinability matter — brass is a practical choice.
Brass offers inherent corrosion resistance superior to uncoated steel, making it suitable for indoor use and light outdoor exposure. For prolonged outdoor or marine environments, apply a light machine oil or grease to the gear teeth and bore to extend service life.
Yes. The 0.5 mod / 20T geometry is commonly used in compact motorized mechanisms including extruder drives, camera pan/tilt rigs, and linear sliders. Confirm that your mating gear or rack is also 0.5 module, and that the bore matches your stepper or servo motor shaft diameter.
Yes, the gear specification is identical across all pack quantities. The only difference is the number of pieces per order. Bulk packs (5 PCS, 10 PCS) offer a lower per-unit cost and are ideal for prototyping, spare parts inventory, or multi-axis builds requiring several gears of the same size.
The securing method depends on the specific variant's hub design. Most pinion gears in this size range use a set screw (grub screw) through the hub to clamp onto the shaft. If your variant includes a set screw hole, use an appropriately sized hex key to tighten against a flat on the motor shaft for best retention. Contact us to confirm the hub detail for your selected bore size.
