Dimensioning and tolerancing is an art form as much as a science. People become very passionate when discussing the right way to perform these tasks. In truth, the techniques are not so black and white, but are highly dependent on the industry, the means of manufacture, and the purpose of the drawing. Drawings might be used for quotes, manufacturing, inspection, assembly, testing, and so on; and the drawings, as well as the dimensioning and tolerancing used, for each purpose need to be somewhat different.
While it is important to follow standards and use drawing conventions properly, this is not an argument that I want to reignite here. In this chapter, I will focus on how the available tools work. You will need to decide for yourself how to apply them in each situation.
The debate on how to get the dimensions from the model to the drawing is much like the "tastes great/less filling" debate. Each side of the issue has valid points, and the question is not likely to be resolved any time soon.
At the center of this debate is whether you should place the dimensions that you use to create the model directly on the drawing, or whether you should use reference dimensions created on the drawing. In the following sections, ...