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Datum
Datum is a core engineering term. Definition, usage notes, and a practical example.
Definition
A datum is a reference surface, axis, or point for measurement and tolerances.
Why it matters
It defines assembly function and measurement repeatability.
How it is used
In a design check, first define the relevant load, dimension, material, or flow condition. Then interpret this term by its role in the formula and compare it with limits.
Example
The main seating face in a fixture is often the primary datum.
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Formulas
No formulas added for this term.