Really think of the X,Y graphs you drew at school. You can choose any quadrant but its much easier playing in the positive quandrant which places 0,0 at the bottom left and you play in the top right quandrant (Travel +X,+Y). It's easier to have home sensors near 0,0 but I do have a machine that was easier to put the y home sensor at max Y so I have a very long home_offset to move it back to the 0,0 position. I have thought of changing the setup so I work in the bottom right quadrant so 0,0 is at top left close to the home switch. (travel would be +X, -Y) You never work in raw coordinates as you touch off your g54 offset so 0,0 is somewhere on your workpiece. If you touched off at bottom left of your workpiece, you would be working on the workpiece in that positive quandrant again. Sometimes you would touch off in the centre of your workpiece to bore a hole or make a motor mount, Sometimes you might also touch off at the back left against the corner of your vice jaws if you had a few parts to make. (travel +X, -Y). If I do this, I have a big magnet I stick on the jaws so I have a repeatable position.
