Retaining and Respecting the Nominal Data for a Freeform Scan (Without CAD)

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  • Retaining and Respecting the Nominal Data for a Freeform Scan (Without CAD)

    Yello all, new project/new problem.

    I am making a Master Verification program for a part that has been previously programmed from CAD. Basically, we laboriously measured the part over and over and calculated ‘new nominals’ for the master, so that when inspected, it should report very little deviation (a few tenths at most - noise) to indicate that the calibration is in good shape.

    The scanning issue I'm having is that while I went through the trouble of taking the actual measured scan data to create a freeform scan that conforms to the actual master, rather than the model, I get ZERO deviation. Even if I put a piece of wrinkly tape on the surface, it still reports no deviation, even as you can see the tape blip in the graphic analysis.

    The original program’s scan was an advanced perimeter scan using the CAD model, with Find Noms, and CAD Comp. This Master Program is using a Freeform Advanced scan, but not the model, so ‘Find Noms’ is out. I have tried various things using both Master, and Nominals modes, but neither has managed to flag the tape on the surface (with a profile tolerance of 0.001”). I also tried reverting to Find Noms, but with the CAD removed - samesies...

    How do I get PC-DMIS to respect the actual nominal data provided to the freeform scan? It seems to just like to accept whatever it scans as the new nominal...

    By the way, I am using PC-DMIS 2011 MR1 with a Leitz LSPX-1S Probe, and also tried it on one with PC-DMIS 2013 MR1 with a Leitz LSPX-1H.

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