Drill Wandering: Causes and Corrective Actions
Problem Description Drill wandering is a gradual deviation of the bore centerline as the drill advances. It differs from a sudden step or jump caused by hitting a hard inclusion — wandering is a steady drift that increases with depth. I have seen 400 mm deep holes where the exit was 1.2 mm off center while the entry was perfectly located. The problem shows up in two ways. Gradual drift creates a curved bore that fails straightness specs. Step wandering, where the bore jogs at a certain depth, usually means the drill hit a material change or hard spot. The distinction matters because the fixes are completely different. ...