General recommendations for stepper motors on CNC routers - set the DIP switch to reduce current when motor is stopped. You do not need as much torque to keep the motor in position when not moving, so you can safely reduce the current and therefore motor heating. Then adjust the motor current based on the motor temperature. Select a current setting, and check the motor case temperature with your hand after, say, 30 minutes. If you can hold it comfortably, try increasing the current. If it is too hot to touch, reduce the current. Aim at a motor temperature of about 60degC, which is about the maximum you can hold. Stepper motors are designed to run at these kinds of temperatures. Current ratings, specification sheets, etc, give you a first guess, but in practice you just want as much current as possible without the motor becoming too hot.