A coupler connects two things together. This chapter consists of step-by-step instructions for making a coupler that, in this case, connects the selected gearhead motor’s shaft to a LEGO cross axle. The general nature of this coupler is applicable even if you choose a different motor or a different type of wheel.
A coupler is needed because the shaft of the chosen motor is neither the correct shape nor the correct size to accept a LEGO wheel. Even if glue or solder could adhere them together, the robot would probably need to be disassembled or experimentally modified at some point. This would rule out permanent adhesion of ...