Axis scaling errors - is this just to be expected with C7 screws?

[magicniner]

Could it be C7 ballscrew accuracy, where I need to tune the steps accordingly?

You should always start with a calculation that should give you correct movement per step, then accurately measure moves of various lengths in various places to see if you need to tweak your settings and if necessary adjust and re-check.

Assuming you don't have backlash or lost steps then if you cut a rectangle and it's corners are square then your machine is cutting square, if it's square but the width and/or length is off then it's axis movement calibration, just tweak your steps settings to give the correct moves and then check at several points along the axis travel that it's right.

Nobody Expoects The Spanish Inquisition ;-)

- Nick