Doing it wrong all this time!

[spluppit]

Charlie as i know your build (as i made some of the parts for you) It looks like your orientation is correct in my book ( as you stand in front of the machine). In the case of your machine the longest travel is left and right, this would be your X. The head traveling away from you and towards you is your Y. The Z Axis as always never changes and is is the head up and down directions. This is the standard configuration for any milling machine. In the technical sense the X and X doesn't really matter as long as you know what each one is. As i described above is the standard configuration that's been used for the last zillion years.