I took Architectural Drafting at Pinellas Technical College (known then as Pinellas Technical Education Center, or PTEC). In drafting, a section is a view that shows the interior of an object (as if the object had been “sliced through” by an imaginary bandsaw). An offset section similarly shows interiors, but the “slice” does not follow a continuous straight line; rather it can show interiors of different depths within the same view of the object. Below is the Performance Evaluation drawing for this particular lesson. Provided were the dimensioned face and top views of a holder bracket; the student was required to reproduce these two views (without dimensions), then draft the offset views based on cutlines AA, BB and CC.
A fellow student of mine, who had little problem with other portions of the curriculum, and who in fact was quite good at freehand illustration, was oddly enough having trouble with offset sections. He understood the concept of the offset section, yet he was having trouble visualizing it in order to then actually draft it. So, I drew this series of isometric projections below as an attempt to help him with his visualizing — and as a challenge to myself, as well.