Hi,
that is the difference between absolute movement and incremental movement, the two different modes are called into effect by either g90 or g91.
Usually your X-Y moves on a plasma table are absolute, so the torch will move to x1y1, x2y2, x3y3
etc in sucession. The Gcode for that would look like this:
g90 ; Absolute mode
g1 x1 y1
g1 x2 y2
g1 x3 y3
If you want to move the Z axis incrementally between moves it would look like this:
g90 ; Absolute mode
g1 x1 y1
g91 ;Incremental mode
g1 z 0.05
g90 ;Absolute mode
g1 x2 y2
g1 x3 y3
Note that what you cant do is have one axis move incrementally while the others move absolutely, Mach is in one mode or the other. You need to switch
between modes.
As a consequence it can be problematic to use both modes within a Gcode program, it so easy to lose track of which mode you are in and call
a move g1 x5 y5, expecting the machine to go to x=5, y=5 but in fact its in incremental mode and it goes 5 to the right and 5 backwards, not what
you intended at all!
Use with caution.
Craig