A hole and a shaft can look perfectly correct on a drawing and still turn into a bad assembly on the shop floor. One shaft stops halfway into the bore. Another part presses together, but the housing flares at the entrance. A third assembly works in raw machining and then becomes impossible after anodizing. That …
Hole position in CNC machining becomes a real problem when the parts reach the bench and have to go together without forcing, slotting, or reworking anything. On paper, the holes may look fine. The inspection sheet may show acceptable sizes. The machined surface may even look clean and well finished. Then assembly starts, and the …
Polishing is often scheduled as a finishing step. In precision machining, it is still material removal. When material comes off the surface, geometry moves. Sometimes it moves only a few microns, but tight tolerance parts operate in microns.
Consider a simple example. A shaft at Ø20.000 ±0.01 mm has a total tolerance width of 20 …
