G74 - left hand tapping cycle: G74 X1. Y1. Z-.8 R.400 F30 G99

The left hand tapping cycle rapids to the XY coordinates and then to the R plane where it begins to feed the spindle down and counterclockwise at a feed rate of F to a depth of Z. The spindle will then reverse and feed upward as the same federate to the R plane. G99 will rapid to the initial plane..