When people talk about CNC “precision,” they usually mean the final number on the part. But what actually determines that number is a whole stack-up of micro-errors happening simultaneously. Think of it like this: a machine never misses by a mile; it misses by a few microns in 12 different ways that add up. Here are the ones pros watch carefully: • Servo lag: Your machine tries to follow a toolpath, but every axis has a slight delay—especially during sharp corners or high acceleration. That’s why some parts show “bulged” radii when pushed too fast. • Tool wear evolution: Carbide doesn’t die suddenly—it slowly rounds off. That rounding changes cutting pressure → cutting pressure changes deflection → deflection shifts your actual dimensions. Experienced machinists can “see” tool wear just from the sound of the cut. • Machine kinematics: 3-axis machines map motion directly, but 5-axis machines use kinematic chains. If your rotary axes aren’t perfectly calibrated, small angular errors...