Change the work plane in 4 and 5 axis machines using G7

This is totally new to me, I have use the machine on and off in a couple of years but never had the energy to take the G7 function to my mind.
It can be a big deal to handle specially on the machine with a rigid table, indexing mill head and rotating C-axis..
This indexing spindle head can be turned 0 to -90 degrees only.
With the G7 function you can order the machine to mill/drill of the opposite face of the part where the milling head can not reach. The smarthead of machine knows that it need to repositioning the C-axis to reach the face automatically, brilliant, I know. Then comes the question, what happen to the zero point, axis and axis directions and so on.


I will show an easy method to start with the top plane on the workpiece and change to the nearest plane (Right side/ X-) and what happens to the axis and axis directions.


The program
G54 I97
T12 M6 (drill)
S1000 F200 M3
M57 (on our machine, unlock head angle over -31deg)
G0 X10 Y10 Z10 (positions before)
G1 X0 Y0 Z0 (touch the Zeropoint with the tool)
G0 X-100 Z100 (safe position before Indexding the head)
G7 B5=-90 L1=2 (turn the coordinate system to the side of the workpiece)
G0 X10 Y10 Z10 (position before)
G1 X0 Y0 Z0 (touch the same zero on the right side of the workpiece)
G0 X100 Z100 (Go up in X+ and to the right in Z+, Wierd?)
G7 L1=1 (Leave G7, see the late comment down below)
M30

The machine axis, C-axis is the table not the spindle and I'v got no A-axis..

As you see on the video, the G7 L1=1 just angle the head to zero and I was ½inch from killing my expensive tool laser unit in the end of the video. Try G7 G5=0 L1=1 instead (or L1=2) for keeping the zero on the tool edge.

Be safe, mistakes costs a lot and the wise man do not know everything.

A picture showing the zero position in -90deg (G7 B5=-90 L1=2), the corner is the zero point