Can I disagree with some of thoughts here?
First, it depends on the CMM and of the calibration.
If it's only a ball bar, maybe 1 day is enough.
Personnaly, I would refuse a KOBA measurement when the KOBA stayed in a car at -20°C or +40°C !!!!!
So one day is far too short !!!!!
In addition, I wouldn't remove the fixtures without some tests (If the fixture is large, maybe they can't calibrate the cmm), but if the weight of the fixture is high, then the cmm geometry depends on it (especially the pitch), so calibrating without the fixture can give a nice paper for quality management but nothing really good for the geometry.
So, a easy test is putting a acurate spirit level at a end of the cmm before removing the fixture, and look if the level changes while removing.
If yes, you have to find a weight equivalent, and put it in place of the fixture, at its center of gravity.
Fortunately, I agree with leaving in place the changer, except if it take too much place...
It's friday, I wish you all a nice week-end, far from COVID !
