a cut is taken (no matter how small), or a temperature change of a few hundred degrees takes place (no matter how temporary), the workpiece, or a portion of it, is likely to spring into a new shape, even if the movement is extremely small. In some cases a movement of a fraction of a micrometre in one area is amplified in lever fashion to create a positional error of several micrometres for a feature of the workpiece several decimetres away. It is factors such as these that sometimes preclude finishing by boring and turning as opposed to internal and external cylindrical grinding. At the extreme, no perfection of machining or grinding may be enough when, despite the part being within tolerance when it is made, it warps out of tolerance in following days or months. When engineers are confronted with such a case, it drives the quest to find other workpiece materials, or alternate designs that avoid relying so heavily on the immobility of part features on the micro or nano scales. See also Drilling Laser drilling Horizontal boring machine Jig borer Single-pass bore finishing References Bibliography Hole making Machining de:Drehen_(Verfahren)#Innen-_und_Außendrehen