FYI
Forum Member kf2qd set his KX3 this way:
Spindle Axis - Enabled - Green Check, Step Pin# - 14, Dir Pin# -16, Dir LowActive - Red X, Step Low Active - Green Check, Step Port - 1, Dir Port - 1
Under the Spindle Setup tab -
Under Motor control there is a check in the Use Spindle Motor Output and Step/Dir Motor, PWM Base Freq is 5 and minimum PWM is 0.
Under General Parameters all are 1.