Full, Half and Part Sections

Full, Half and Part Sections

Grade 10 introduced the sectional view. Grade 11 adds the choice of which kind of section to use, and that choice is assessed.

Full section. The cutting plane passes right through and the whole near half is removed. Use when the interior matters everywhere.

Half section. Used on symmetrical parts only. One quarter is removed, so one half of the view shows the exterior and the other shows the interior — two drawings in the space of one. The two halves are divided by a centre line, not a solid line, because no edge exists there.

Part (broken-out) section. A small local area is cut away to reveal one feature, bounded by an irregular thin break line. Use when only one detail needs exposing and a full section would destroy useful exterior information.

Worked example. A symmetrical pulley: a full section removes all exterior detail. A half section keeps the outside profile visible on one side and shows the bore, boss and web on the other — the better choice, and the one a marker looks for on a symmetrical part.

Core checkpoint: Choose the section type from what the reader needs to see, and justify it. A half section on a non-symmetrical part is wrong.