Engineering Drawing for Manufacture

When it comes to drawing a part to be manufactured for real, it is not necessary to add GTs to each and every feature. From my experience, the vast majority of features do not need them since the common manufacturing processes achieve the accuracy required in the majority of cases. For example, the dowel perpendicularity in Figure 5.15 is obviously important but provided a sufficiently accurate manufacturing process is chosen, a GT is unnecessary. An understanding of the accuracy that can be achieved by typical manufacturing processes (Figure 4.11 and 5.6) normally negates the need for a GT. However, that having been said, there is usually a need for them to be used where there is a functionally sensitive feature like a shaft running in a journal.