I put some calipers on my shapeoko pro today because I had a feeling that it wasn’t jogging the right distances I’m telling it to. If I jog in any direction, say 0.1 inches, it moves like a quarter of an inch.
Files seem to be cutting the right size, at least as close to the right size as a desktop cnc would.
Please try clamping a pen to the router (as was done for “Hello World” and then taping a bit of paper to the machine working area — move close to one corner and jog down so as to make a mark and set zero there, then move in a straight line a almost to the edge of the paper using the jog controls and make a second mark and note the distance noted in CM from origin, then use a ruler to measure to the center of the mark.