Do you understand the tolerances in CNC machining?

Machines are very precise and some are capable of producing parts with an accuracy of ± 0.0025mm. That's a quarter the size of a human hair. However, tolerances vary between CNC machines and are usually specified by the manufacturer, for example, 0.02mm is a typical average tolerance. Assumes standard prototype and production machining tolerances of +/- 0.005 inches (0.13 mm). This means that the position, width, length, thickness or diameter of any part feature will not deviate from the nominal value by more than this value. If you plan to machine a 1" (25.4mm) wide bracket that will measure between 0.995 and 1.005" (25.273 and 25.527mm) and the bracket has a 0.25" (6.35mm) hole in one leg, the diameter of the bracket will be is 0.245 to 0.255 inches (6.223 to 6.477 mm). This is pretty close, but if you need more precision, judged by part geometry and material, make sure to note this in the part design when uploading the file for a quote.