I have a part that is 115 inches long and has a primary datum feature that is essentially a small segment of an enormous arc. Secondary and tertiary features are both holes drilled on the primary feature. I started with an iterative alignment to synchronize the part and model and then probed points on datum feature A, measured circles datum B then C. I then constructed a plane from datum A, defined my datums and used XACT measure to report other hole positions relative to ABC.
I feel I did this wrong... due to constructing the plane from datum A as the true vector of the constructed plane can incorporate additional error (or so I've read). I know there may be a few ways of doing this but what would be your ideal way of inspecting a part like this? Every feature on the part was relative to this datum structure.
I started with an iterative alignment, took a few points on the end faces, the edges of the part and top of the part. After this could I have just created a vector least squares best fit alignment to the primary feature (then exit best fit window) and origin to B and rotate to C?
In the beginning (after creating an iterative alignment) I tried to constrain rotation of X and Y and translation on Z with the points probed on datum A but i was not successful (not sure why), since I don't use the best fit alignment much.
(to better visualize this part, this pretty much looked like a 115" long by 8 inches wide, .500 thick with holes on it BUT it was formed, carbon fiber, and primary datum is irregular/banana shaped)
