Iso Tolerance Standards [updated] Direct

Why interesting? In , using ISO 286 , if a drawing says ⌀25 H7/g6 :

The ISO system uses a clever alphanumeric code to define tolerance. If you have ever seen a drawing with a notation like , g6 , or P6 , you are looking at ISO tolerance codes. iso tolerance standards

Tight tolerances cost money. Achieving a tolerance of $\pm 0.001mm$ requires precision CNC machines, temperature-controlled environments, and slower cutting speeds. By using ISO standards, engineers can specify the "loosest" tolerance that will still allow the part to function. An H9 fit is cheaper to produce than an H6 fit. The standard forces engineers to be intentional about cost vs. precision. Why interesting