Referees at sporting events can fuel elation or outrage with their calls when it comes to a favorite team, but in truth, these people are needed to provide an impartial interpretation of the rules of the game.
In mass-production industries, it has been realized that Product Design (PD) departments and Manufacturing Engineering (ME) departments under the same organization show quite different interests in the same product line.
While John Goodman and Arnold Schwarzenegger are both 6’2”, few would argue that they have similar body shapes. What this says, simply, is that measuring size does not necessarily say anything about shape.
What is GD&T? GD&T, namely “Geometric Dimensioning & Tolerancing,” is a symbolic language with which to 1) research, 2) refine and 3) ultimately “encode” the functions of each feature of a machine part by specifying permissible limits of imperfection.