Because of my job I do have access to a 3D scanner and I did use it for several of the difficult parts but even then using that to find the exact hole location is difficult because the holes come through as gaps in the scan relative the the angle they're scanned at. I believe that the parts I modeled are correct but the holes are not in the perfect locations to line up from part to part. I mean even after I do my best to measure and things don't line up I save the values I measured and create a new configuration with the dims tweaked to "look right" my problem is of course that I may be off in both parts and I may only fix one... or I may fix both when the one was correct. I try to use my best judgement as to how difficult teh hole was to measure but it's still quite difficult and time consuming.
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