3. What is the difference between chain dimensioning and datum dimensioning?

Chain dimensioning involves placing dimensions in a linear sequence, where each dimension is referenced from the previous one, which can lead to cumulative tolerances and potential inaccuracies. In contrast, datum dimensioning establishes a reference point or surface (datum) from which all other dimensions are measured, ensuring consistency and precision across the entire part. This method reduces the accumulation of tolerances and enhances the reliability of the dimensions. Overall, datum dimensioning is generally preferred for critical applications where accuracy is paramount.