Is this important?
I would imagine so, considering all the parts have datums, but what is the difference from, say, setting a point as Datum A and dimensioning a feature to Datum A, and setting a point and dimensioning a feature to said point?
It sounds like you aren't talking about Datum Definition at all. That's a specific thing where you are using XactMeasure and when making a Position dimension, you define the datum for use in building your DRF to the Feature Control Frame.
Distances can be 2D or 3D, and can be parallel or perpendicular to an axis or a feature. If you have a datum feature to another feature, the datum feature should be picked 2nd. If you have a line or plane, the vector of the distance can be related to the vector of the feature. Point to point, you need to specify a direction, either to an axis or 3D. It all depends on the feature, the specific callout, the print, etc.
A 3D distance is measured from centroid to centroid, regardless of orientation. 2D distance is workplane and feature dependent. You must be in the right workplane and specify the right measurement orientation.
It sounds like you aren't talking about Datum Definition at all. That's a specific thing where you are using XactMeasure and when making a Position dimension, you define the datum for use in building your DRF to the Feature Control Frame.
Distances can be 2D or 3D, and can be parallel or perpendicular to an axis or a feature. If you have a datum feature to another feature, the datum feature should be picked 2nd. If you have a line or plane, the vector of the distance can be related to the vector of the feature. Point to point, you need to specify a direction, either to an axis or 3D. It all depends on the feature, the specific callout, the print, etc.
A 3D distance is measured from centroid to centroid, regardless of orientation. 2D distance is workplane and feature dependent. You must be in the right workplane and specify the right measurement orientation.
