Some thirty odd years ago I jotted down a formula to calculate the diameters of three dissimilar gage pins that when bundled together with rubber band could be used to gauge a hole of larger diameter. Recently, the need arose again and after the disappointment of searching my memory, I undertook the exercise anew. In my experience, the most common gage pin sets a machine shop will have run from .061” – .250” and .251” – .500”. These occur in a variety of tolerance classes. The following has been formulated for “minus” gage pin sets. Manipulation of applicable hole tolerances...
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