Hex Coupler 4mm Bore Motor Shaft Connector

Connect your motor shaft directly to a hexagon-drive wheel with this Hex Coupler, a compact brass connector purpose-built for smart cars, robotic vehicles, and small hobby robots. Machined from high-quality brass, it bridges the gap between a round 4mm motor shaft and a hexagonal wheel hub, giving you a secure, torque-transmitting connection without needing to modify either part.

One end of the coupler features a hollow bore that slides directly onto the DC geared motor’s output shaft, secured in place with a fastening screw, while the opposite end forms a hexagonal socket that mates with standard hex-drive wheels used on RC cars, smart cars, and small robot chassis. The simple, single-piece design requires no special tools or skills to install, and ongoing maintenance is limited to occasionally checking and tightening the set screw as needed. Its brass construction keeps the connection rigid and insulated, maintaining stable alignment even as the wheel spins under load.

This hex coupler is a go-to component for makers and students building line-following robots, obstacle-avoidance cars, and other small wheeled platforms powered by common DC geared motors. It reliably transfers the motor’s rotating power to the wheel without slipping, making it a practical low-cost part for STEM projects, robotics clubs, and DIY vehicle builds. Note that wheels and motors are sold separately.

Specification:

• Material : Brass
• Bore Diameter : 4mm
• Hexagonal Side : 7mm
• Hex Height : 6mm
• Cylinder Outer Diameter : 11.5mm
• Cylinder Height : 12mm
• Fastening Screw : M4