On my shapeoko 3 XXL, I was doing some testing on contours to take out the machining marks left from cutting out contours with multiple depths and ended up with the side actually being scalloped.
I cut the contour with 1mm depth of cut at about 60 inch/min with the carbide spindle. I then took 10 passes at full depth at the same speed, only taking off 0.1 mm per pass until I took off an additional 1mm.
This left the contour being scalloped (concave) rather than flat 90° to the top. Is this simply because of bit deflection?