Hi Billy,
Based on your description and the drawing, there is not enough information to give you an accurate answer. I would need to see the actual drawing and I need to know how this part fits and functions in the final assembly. Whether this is a final product drawing or a detailed assembly with separate parts at each end will influence how the drawing is dimensioned and toleranced, also.
For example, if this in a single part drawing that has one continuous hole through the full length of the part, then it would be appropriate to specify this hole as a single datum letter and reference it as a primary datum in the feature control frames.
However, if this is an assembly with two separate flange details at each end, then it is appropriate to specify the holes at each end as separate datum letters since they are separate features. However, if the part relies on both of these holes at each end to provide the primary location and orientation of the part, then you would reference them as co-primary A-B datum features in the feature control frames. For example, A-B.
Thanks for writing. It’s a good question. If you’d like to send more detailed information privately, I can give you a more specific answer.
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