I assume you do not have synchronous tap on the machine, this automatically syncs the Z axis to spindle rotation, the G84 will put this into effect when the necessary parameters are entered in the instruction. With G84 you can also use a floating tap holder.
Some machines have G63 which is tapping cycle, which you should be able to use with floating tapping if you do not have syncronous spindle, which is what you want to do I believe?
You have to know fairly accurately exactly what your spindle speed is running when S value is programmed, and then you program the spindle speed and feed rate to conform to the pitch of the thread, the G63 ignores spindle & feed rate overide and the accel/decel is ignored so it is mainly manual entry,
i.e. G63 SP speed - feed rate - Z depth - G03 - G04- Z return - G5.
Through-hole tapping is less of a problem than bottom hole, due to no synchronous spindle.
Your floating tap holder will hopefully be in range for bottom hole tapping, if you get the feed rate etc right.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.