Some people think axis length has something to do with it but that is wrong. The confusing thing is you and I can say that different axis are the X and both be right but there is only one correct way to name your axis.
It all depends where you stand!
Getting it wrong
Getting X & Y axis mixed up will make your project cut at 90 degrees to what you see on the screen of your controller and your Cad / Cam software. Not a major issue if you want to live with it and simply by stepping to the side it will all lok right. Not quite so forgiving is mixing up the +ve & -ve directions of the axis. Getting these wrong will see your project come out mirrored in one or both directions depending whether you have one or both axis wrong. Only a few projects will stand up to this type of error. If you remember that X0,Y0 is in the bottom left and X max, Y max is in the top right then you can't go wrong.
It's so simple but so important to get right and not if things don't look right to you on your machine you now know why.
Until next time.