Pitfalls of using the granite (NOT THE PART) as a Datum Alignment Feature

I can't point you towards a specific article. I can tell you exactly why its bad, though.

If you're in an industry that procedurally requires the use of calibrated measurement equipment (AS9100, ISO 13485, ISO 9001, etc...) then you can't use the CMM's granite table as a datum simulator because it isn't calibrated as a part of the machine (or at all). The table is just that. A table. By design, it is a reference only surface that you are ONLY to put stuff on for the machine to then measure. It is pretty flat (my table is 0.0025 across the entire surface and I have a 7107) but without that precision lapping and certification from a 17025 facility, its just a rock.

What I advise in this situation:
Depends on your industry. I have situations where my tolerance is ± 0.015 or more, it isn't a finished part dimension (more would be cut off later)....THEN I will beep off of the table. For FINISH DIMENSIONS on QMS regulated stuff, if the bottom surface of your part is a datum and you'd like to use the table as a datum simulator, don't do that. Instead, use calibrated inspection risers or gage-blocks or something like that. Have the machine probe those surfaces in DCC mode, create a plane, load your part on to them once you're done making the plane, then measure your part. Handle the measurement of the blocks with readpoints & comments that have pictures and the loading/unloading of the part with comments that have pictures. You could also have your company make an inspection fixture, measure the fixture itself & create an origin, THEN load your part onto it and go to town.

I can't point you towards a specific article. I can tell you exactly why its bad, though.

If you're in an industry that procedurally requires the use of calibrated measurement equipment (AS9100, ISO 13485, ISO 9001, etc...) then you can't use the CMM's granite table as a datum simulator because it isn't calibrated as a part of the machine (or at all). The table is just that. A table. By design, it is a reference only surface that you are ONLY to put stuff on for the machine to then measure. It is pretty flat (my table is 0.0025 across the entire surface and I have a 7107) but without that precision lapping and certification from a 17025 facility, its just a rock.

What I advise in this situation:
Depends on your industry. I have situations where my tolerance is ± 0.015 or more, it isn't a finished part dimension (more would be cut off later)....THEN I will beep off of the table. For FINISH DIMENSIONS on QMS regulated stuff, if the bottom surface of your part is a datum and you'd like to use the table as a datum simulator, don't do that. Instead, use calibrated inspection risers or gage-blocks or something like that. Have the machine probe those surfaces in DCC mode, create a plane, load your part on to them once you're done making the plane, then measure your part. Handle the measurement of the blocks with readpoints & comments that have pictures and the loading/unloading of the part with comments that have pictures. You could also have your company make an inspection fixture, measure the fixture itself & create an origin, THEN load your part onto it and go to town.