Sectional Views and Conventions
Sectional Views and Conventions
This domain tests cutaway views that reveal internal form. The cutting plane, hatching and omitted hidden lines must follow drawing conventions.
Core rules
- A cutting plane is shown by a chain line with thick ends and arrows showing the viewing direction; label it A-A.
- Hatch only solid material cut by the plane, with thin, evenly spaced 45° lines. Adjacent parts hatch in opposite directions or at different spacings.
- Do not hatch standard parts such as shafts, bolts, nuts, pins and keys when cut longitudinally. Ribs and webs are also left unhatched.
- Omit hidden lines in a section unless they are needed for clarity.
- Show visible edges behind the cutting plane. Use half, offset or revolved sections when only part of the object needs exposure.
Worked example
A bush has a 40 mm outside diameter, a 20 mm bore and a length of 30 mm. Draw a full section. Draw the outer rectangle 40 x 30 and the bore as two visible lines 20 mm apart. Hatch only the two annular walls. Add a centre line along the axis. Reasoning: the cutting plane passes through the axis, so the bore is open and its walls are visible; the metal walls are solid and therefore hatched.
Traps
- Hatching across the bore.
- Hatching a solid shaft cut along its axis.
- Leaving hidden lines in a full section.
- Reversing the cutting-plane arrows.
- Uneven or scribbled hatching.