This isn't a PC-DMIS question but I thought someone here might know the answer. What is the logic behind having a Ø called out at 20.0mm with a -.007 / -.04 tolerance. Why not just make the Ø19.993 +0 / -.033?
Changes during design & testing of the part or the mating component can often create unusual tolerances. Instead of changing a feature on a cad that could potentially affect many earlier elements, the adjustment gets pushed to the tolerances. Especially if you're in the final testing phase and found a diameter would fit better if it was .005" larger, then instead of going back into cad and "redesigning" the part which could potentially change any restraints and constructs tied to it, it's less effort to tag the tolerances to account for the change.
Changes during design & testing of the part or the mating component can often create unusual tolerances. Instead of changing a feature on a cad that could potentially affect many earlier elements, the adjustment gets pushed to the tolerances. Especially if you're in the final testing phase and found a diameter would fit better if it was .005" larger, then instead of going back into cad and "redesigning" the part which could potentially change any restraints and constructs tied to it, it's less effort to tag the tolerances to account for the change.
