If you have ever installed a window, door or kitchen cabinet, you know the importance of shims—thin wooden wedges that help keep things square and level.
Engineers may not want to admit it, but large mechanical assemblies—airplanes, tractors, industrial machinery—are no different. Sometimes, mating parts just don’t meet the way they were designed, due to tolerance stack-ups. Custom-made precision shims solve the problem, but, instead of cedar or pine, shims for mechanical assemblies are made from metal.