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When a misaligned or loose shaft connection causes vibration, slippage, or premature wear in your RC car, robotics project, or DIY motor drive, the fix starts with the right flexible coupling coupler. This connector is designed for hobbyists, makers, and engineers who need a dependable, low-backlash shaft-to-shaft link without machining custom parts.
Each flexible coupling coupler is machined from aluminum alloy with a spider-jaw or beam-cut flexible body, available in bore sizes of 3 mm (~0.118 in), 4 mm (~0.157 in), and 6 mm (~0.236 in). The outer diameter is typically 19–25 mm (0.75–0.98 in) and overall length typically 25–30 mm (0.98–1.18 in), depending on bore size. Sold individually (1 pcs), in pairs (2 pcs), or in sets of four (4 pcs).
Typical use cases include connecting stepper motor shafts to lead screws in CNC routers, linking DC motor output shafts to RC car wheel axles, and coupling encoder shafts in robotics and automation rigs — all scenarios where a rigid coupling would crack under angular or parallel misalignment.
Choose 3 mm, 4 mm, or 6 mm bore to match your motor shaft or axle diameter exactly — no adapters needed.
The flexible body accommodates angular, parallel, and axial misalignment, reducing vibration and protecting bearings in your drivetrain.
Sized for common hobby and maker shaft standards — fits RC car wheel hubs, robot drive trains, and small CNC axis drives.
Machined aluminum alloy body keeps rotating mass low while providing sufficient torque transmission for hobby-grade and light industrial applications.
Hex set screws on each jaw clamp firmly to the shaft, preventing slippage under load without permanent modification to your shafts.
Order 1, 2, or 4 pieces per purchase — ideal whether you need a single replacement or a full set for a multi-axis build.
| Bore Size Options | 3 mm / 4 mm / 6 mm |
|---|---|
| Material | Aluminum alloy |
| Outer Diameter | Typically 19–25 mm (0.75–0.98 in) — See variant options |
| Overall Length | Typically 25–30 mm (0.98–1.18 in) — See variant options |
| Clamping Method | Hex set screw |
| Coupling Type | Flexible jaw / beam-cut |
| Finish | Natural aluminum (anodized finish may vary) |
| Max Shaft Misalignment | See variant options |
| Quantity per Order | 1 pcs / 2 pcs / 4 pcs |
| Compatible Shaft Types | Round D-shaft and round shaft |
Measure your motor output shaft diameter with a caliper. Select the bore size that matches: 3 mm for micro motors and small encoders, 4 mm for common hobby DC and stepper motors, and 6 mm for larger gear motors and RC car axles. If your two shafts are different diameters, contact us to confirm mixed-bore availability.
Yes. The flexible jaw or beam-cut design absorbs angular misalignment (typically up to 1–3°), parallel offset, and minor axial movement. This protects motor bearings and reduces vibration in your drivetrain. For severe misalignment, realign your mounts first for best results.
The hex set screws clamp firmly to round shafts and provide reliable torque transmission for hobby-grade and light-duty applications. For D-shafts, the flat face gives extra grip. Tighten with the appropriate hex key to the recommended torque — over-tightening on very thin shafts (3 mm) can cause indentation, so apply firm but controlled force.
Yes — the 4 mm and 6 mm bore variants are commonly used to connect DC motor shafts to RC car wheel hubs and tire axles. The lightweight aluminum body minimizes unsprung weight, and the flexible element absorbs road-induced vibration that would otherwise stress the motor bearings.
Aluminum alloy offers good natural corrosion resistance for indoor and sheltered outdoor use. If your application involves moisture or humidity (e.g., outdoor robotics or marine RC), consider applying a light coat of corrosion-inhibiting spray to the coupling body. The anodized finish (where present) adds an additional protective layer.
The listed variants feature the same bore on both ends. If you need to connect a 3 mm shaft to a 6 mm shaft, for example, please contact us to confirm whether a mixed-bore variant is available, or consider using a shaft adapter in combination with this coupler.
For a 3-axis CNC router, you typically need one coupler per axis (3 total). For a 4-wheel-drive robot, you may need 4 couplers. The 4 pcs quantity option offers the best per-unit value for multi-axis builds. Mix bore sizes across separate orders to match each axis's shaft diameter.
