G14 causes the secondary spindle to become the primary spindle, so that the secondary spindle reacts to commands normally used for the main spindle. For example, M03, M04, M05 and M19 affect the secondary spindle, and M143, M144, M145, and M119 (secondary spindle commands) cause an alarm.
G14 automatically activates Z-Axis mirroring. If the Z Axis is already mirrored (Setting 47 or G101), the mirror function is canceled.
G14 is canceled by G15, M30, at the end of a program, or when you press RESET.