To simplify inspection, should you specify fewer or more dimension datums?

• A. Fewer
• B. More
• C. The same
• D. None

Answer: (A)

Using fewer datums keeps the measurement setup simple and fast. Datums define how the part is located and oriented for inspection, so every extra datum adds another reference frame to establish, align, and verify. With a minimal, robust set of datums, you can quickly position the part, reduce fixture complexity, and decrease potential alignment errors, while still constraining the features you need to measure. Adding more datums tends to complicate the inspection process, increase fixture and programming effort, and can introduce additional tolerance stackups. So, to simplify inspection, specify fewer datums.