1st I will explain what my part looks like. If you take a 8" long by 3" wide by .500" thick plate and fold it around a 72" cylinder, you now have what my part looks like (sort of, please excuse my super lame drawings. Datum B is the center axis of a 72" cyl not 36").
Datum A: top plane (in this case the .5" thick surface top of the part)
Datum B: Is the center axis of the 72" cylinder
Datum C: One of the sides
I am trying to inspect it with the arm (Level to A, origin to B, rotate to C) but datum B is my main problem (well, the alignment is my problem). Anyway, the Arc segment of this part is small (this part is only about 8" long). What would be the best way to measure this? (I know, vague question). All holes have to be within a .015 positional tolerance zone. I know for sure I cannot get a repeatable measurement on the 72" (datum B) segment with the least squares algorithm. Will changing it to fixed rad algorithm help? (Haven't tried it since where I work doesn't allow much time to "play" with the equipment).
Reason I got into this mess is because our DCC CMM programmer is old school and we feel he should use an iterative alignment. He basically constructed points and lines at the part's ends and used the chord length to trig everything out and thats how he derived his origin. Yes, theoretically correct but the part's edges are not flat and this part is not really a rectangular block (that is why I said up top that this part is "fairly simple" heh heh). I just want to make it as simple as possible so someone can visualize the part a bit easier.
Help please.
Thanks.
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