T

he actual purpose of GD&T:

It’s common to think that the primary purpose of GD&T is to unambiguously communicate design intent to manufacturing and inspection. In fact, the most important objective is to ensure that what we communicate is worth communicating, and that it represents a part that can be guaranteed to assemble and operate, if the specified tolerances are met. Bad GD&T—the decorative kind—however, is very dangerous. Machine shops always try to manufacture exactly what we say we want, but if what we say we want isn’t what we actually need, they’re generally held responsible, often not rightfully, and we all suffer.

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