Composite Position results

Composite Position results

Another composite position question, sorry john.peterson.

I'm getting some unexpected results and I'm not sure if it's me, or how CMM-M handles composites.

I have a standard positional callout for a pattern of three holes called to datums ABC, that pattern is then datum D.

There is then a pattern of six holes with a composite position ADC and AD.

CMM-M would not let me use "D" as a secondary datum in my FRTZF. My "D" is a circle created from the three holes, and CMM-M wants an alignment feature (line, cyl, etc). So I created a line from two of the holes and used that for my secondary datum in my FRTZF, hoping CMM-M would align to the pattern using that. So I have ADC in my PLTZF, and AD(reference line) in my FRTZF.

I would expect to see my PLTZF report locations relative to D and aligned to C, and my FRTZF to report locations relative and aligned to D. I know we have issues with our setup part, but I'm seeing large deviations in my FRTZF that I would not expect to see, as the holes are put in at the same time. It seems like CMM-M is not aligning to the pattern when doing the FRTZF calculations. Also of note, when I re-run the composite report without a secondary datum feature (just datum A), I get more of the expected behavior and results are in tolerance.