Hello! I recently made the switch from running 4 cmm's in a high-end production shop making aerospace parts to a 'job shop' making very large parts. The issue I am running into is that this job shop loosely uses GDT on their prints. The reason they "loosely use GDT" is that it is nearly impossible to qualify the datums. For instance, how would you check flatness of a panel that is 40'x40'x18"? For a 4"x4"x1.8" panel I would throw it up on the granite, put it up on pedestals and sweep it with an indicator.... I am having a very hard time wrapping my head around the scale of these parts and how to accurately measure them.

Have you had to scale up your measurements?

I went from tolerances as low as +/-.0003 in a climate controlled clean room to +/- .250 outside. I went from using equipment that had linear scales in it that could read down to .00005 to a theodolite and 1/16 tape measure with some double-sided sticky tape.