>>The movement you have shown in all three videos, I would expect if the steppers were not energized!
Yes the steppers were not energized. I confirm that when the steppers are energized I have no play at all.
>>The oval shape that you seem to be achieving, I suspect it is caused by the fact that your “better Z middle” is slightly longer then it should be.
>>By longer, I mean that your X and Y rail will be pushed out of square, in the quadrant of the Z assembly, I’m guessing by 1 to 2 degrees!
I fully agrre with you. I’ll print a scaled “better Z middle” and see what happens.
>>To check this I would move the tool over the same position where you cut that circle/oval. From both ends of the X rail, and on the same side of the
>>X rail drop a plumb bob down to your work surface/table. Mark the two points on this surface and draw a straight line between these two points.
>>Now do the exact same thing on the Y rail. Take a square and check where the lines intersect, are they square?
I didn’t do it but the axes out of sqaure are really evident looking with a square on the tubes.