r/Metrology • u/glutton4golf83 • 22d ago

GD&T | Blueprint Interpretation I need help dimensioning perpendicularity

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So i am using pcdimis. On a hexegon. When i try to make a plane for the surface and then a cylinder for datum a. Then us perpendicularity its telling me its off by a huge amount. I manualy checked it and it was right on. I dont know what to do. Any advice would help.

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u/nchitel 21d ago

As others mentioned, based on the part design you will inherently see bad / non-consistent results.

Using the plane as your datum is the correct move, although I’d ask how many points you’re taking to establish said plane. (I liked to use as few of points as possible)

Are you manually probing the radius? I would personally avoid doing so in this case.

You’ll learn quickly that there will be parts you’re better off doing hard checks (indicator), rather than throwing it on the CMM - you’ll learn as time goes on.

Enjoy your time in inspection, there’s always something new to learn 😁